L-shaped grating couplers engineered with subwavelength metamaterial for sub-decibel coupling loss
D. Benedikovic1, C. Alonso-Ramos1, S. Guerber1,2, V. Vakarin1, G. Marcaud1, X. Le Roux1, P. Cheben3, É. Cassan1, D. Marris-Morini1, F. Boeuf2, C. Baudot2, and L. Vivien1
1Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, C2N – Palaiseau, 91120 Palaiseau, France
2Technology R&D, STMicroelectronics, SAS, 850 rue Jean Monnet – 38920 Crolles, France
3National Research Council Canada, 1200 Montreal Road, Ottawa, Ontario, K1A0R6, Canada
Practically attractive nanophotonic technologies, mostly realized on mature silicon-on-insulator (SOI) substrates, call upon availability of efficient input/output grating-coupled optical interfaces. In this work, we demonstrate, both theoretically and experimentally, ultra-directional L-shaped grating couplers for low-loss light coupling between standard optical fibres and SOI chips. Experimentally, we show grating couplers without and with subwavelength (SWG) transition, seamlessly fabricated with a 193-nm deep-ultraviolet lithography. Coupling loss of -2.7 dB is measured with a low return loss as low as -20 dB. In addition, we propose an apodized L-shaped grating coupler layouts with coupling loss below 1 dB. Apodized fiber-chip grating couplers are designed with a sub-decibel coupling performance, together with substantially relaxed requirements in terms of minimum feature dimensions.
Keywords: fibre-chip grating couplers, deep-ultraviolet technology, subwavelength gratings, metamaterials, silicon-on-insulator platform, silicon photonics
Low Loss Devices fabricated on the Open Access 3 μm SOI Waveguide Platform at VTT
Srivathsa Bhat, Mikko Harjanne, Fei Sun, Matteo Cherchi, Markku Kapulainen, Ari Hokkanen, Giovanni Delrosso, Timo Aalto
VTT Technical Research Centre of Finland, 02044 Espoo – Finland
In this paper, the latest results on some of the building block devices and components fabricated on VTT’s PIC platform, that is based on 3 μm thick Silicon-On-Insulator (SOI) waveguides , is presented. As part of the plans in developing the platform further, AWG and Echelle grating (EG) designs, with insertion loss in the range of 1-3 dB, and an extinction ratio reaching up to 35 dB have been designed and fabricated as part of the recent MPW run, and the measurement results are presented. Novel 45o vertical coupling TIR mirrors have also been realized (with AR coating) as a new building block on this platform, and have been integrated with the waveguides. The measured coupling losses to/from lensed fibers are below 0.5 dB, which are better in comparison to the coupling loss from the etched facets at the edges of the chip (~ 1 dB). The main advantages of this thick SOI platform are low loss, dense integration, polarization independent and broadband operation, high optical power throughput, and smooth transition from prototyping to volume production. Open access via multi-project wafer (MPW) runs, dedicated process runs, prototyping and small-to-medium volume production services are provided.
Keywords: Thick SOI Platform, AWG, Echelle Grating, Fiber-Coupling Mirrors, Low-Loss, Polarization Independent.
Application of Optical Proximity Correction for 193 nm Deep UV enabled InP Photonic Integrated Circuits (Student Paper)
Jeroen Bolk1, Huub Ambrosius1, Sylwester Latkowski1, Nezih Unal2, Daniel Ritter2, Kevin Williams1,
1 Eindhoven University of Technology, Eindhoven, The Netherlands
2 GenISys GMBH, Munich, Germany
We present the first-time application of rule-based optical proximity correction for InP based photonic integrated circuits fabricated with 193 nm deep UV lithography. Simulations of the lithography process were used to systematically predict and preserve pattern fidelity of sidewall gratings to find optimal correction parameters. Optical proximity corrected designs were exposed in ArF resist, demonstrating high correlation with lithography simulation results and exhibiting up to 70% improved pattern fidelity.
Keywords: Optical Proximity Correction, Pattern Fidelity, Sidewall Grating, Deep UV, InP, Photonic Integrated Circuits
Heterogeneous Integration Roadmap – Package Level Systems Integration: A key to maintaining the pace of progress
W. R. Bottoms1, Amr S. Helmy 2
1 3MTS, California – USA
2 The Edward S. Rogers Department of Electrical and Computer Engineering, University of Toronto, 10 King’s
College Road, Toronto, ON M5S 3G4, Canada
Both authors represent different IEEE societies within the HIR leadership; e-mail: email@example.com
In this talk we plan to provide an overview of the heterogenous road map and how it relates to photonics.
Within the talk we shall also set in context the role photonics play within the package level systems integration of electronics, photonics and sensor integrated circuits with the aim of maintaining the pace of progress, as Moore’s
Keywords: Heterogeneous Integration, Package Level Integration.
Large enhancement of longitudinal magneto-optical effect with an all-dielectric resonant guided-mode grating Student Paper
L. Bsawmaii 1, E. Gamet 1, F. Royer 1, F. Celle 1, S. Neveu 2, D. Jamon 1
1Universit´e de Lyon, CNRS, UMR 5516, Laboratoire Hubert Curien, Universit´e Jean-Monnet,
F-42000 Saint-Etienne, France
2Sorbonne Universit´es, UPMC Universit´e Paris 06, CNRS, Laboratoire PHENIX, Case 51, 4 place Jussieu,
F-75005 Paris, France
An integrated device with high magneto-optical response is currently required since there is a high demand on photonic devices employing magneto-optical effects like optical isolators and magnetic field sensors. Thus, we experimentally and numerically demonstrate a significant enhancement of the longitudinal magneto-optical response in transmission and for small angles of incidence, in a subwavelength resonant structure consisting of a dielectric grating and a magneto-optic waveguide.
Keywords: magneto-optics, Faraday effect, Kerr effects, magneto-plasmonic, resonant guided-mode grating.
Using the polarisation response of planar optical waveguides to determine the anisotropic complex refractive index of graphene oxide thick films
WenSin Chong1, SoonXin Gan1, ChoonKong Lai1,2, WuYi Chong1,, Steve Madden2, Duk Choi2, Richard M. De La Rue3,, Harith Ahmad1
1Photonics Research Centre, University of Malaya, 50603 Kuala Lumpur, Malaysia.
2Laser Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 260, Australia.
3Glasgow University Optoelectronics Research Group.
The polarisation response of graphene oxide (GO) coated planar silica optical waveguides has been studied. GO films with different thicknesses have been coated onto a planar optical waveguide with its top cladding removed via plasma etching. The solution drop-casting technique was used for GO coating. GO film thicknesses between 0.1 m and 1.0 m were used. GO-coated waveguides exhibit large polarisation dependent losses – and the polarisation response depends strongly on the GO coating thickness. The response was used, together with finite element analysis, to determine the complex refractive index of the GO film. The complex refractive indices of the GO film, with TE- and TM-polarised light at a wavelength of 1550 nm, were found to be 1.65+0.07i and 1.63+0.001i, respectively. The uncertainty values for the real parts of the refractive index were 0.02 and 0.01 for TM- and TE-polarised light, respectively – whereas the uncertainty values for the imaginary part of the refractive index were found to be 0.0001 and 0.01 for TM- and TE-polarised light, respectively. The estimated uncertainty values are smaller by an order of magnitude when compared with values measured using the conventional method of spectroscopic ellipsometry.
Keywords: graphene oxide, planar optical waveguide, complex refractive index, finite element analysis.
Wideband Static and Dynamic Model of a Tensile-Strained Bulk Reflective SOA
Michael J. Connelly
Optical Communications Research Group, Dept. Electronic and Computer Engineering,
University of Limerick, Ireland.
Reflective SOAs (RSOAs) have promise for applications such as optical modulators in WDM PONS. Bulk polarization insensitive SOAs are realised by the use of a tensile-strained active region, which compensates for different TE and TM confinement factors. RSOA wideband models are required to predict RSOA static and dynamic behaviour. In this paper, we present a wideband static and dynamic model of a commercial tensilestrained tapered waveguide RSOA. Wavelength and carrier density dependency of the material gain and additive
spontaneous emission is determined using full band structure calculations. In the static model, estimation of the amplified signal and spontaneous emission is achieved by an efficient numerical solution of travelling-wave and carrier density rate equations. Unknown model parameters are determined by least squares fitting of modelled and experimental ASE spectrums. The dynamic model extends the static model to permit SOA drive current modulation and is used to determine the RSOA response when driven by multi Gb/s NRZ data signals. There is good agreement between 1.25 Gb/s data simulated and experimental eye diagrams.
Keywords: Reflective semiconductor optical amplifier, modelling, modulator.
Study of Silicon Waveguides with All-dielectric Metamaterial Cladding by Numerical Simulations (Student paper)
Andraž Debevc, Janez Krč and Marko Topič
1 University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana – Slovenia
By introducing all-dielectric metamaterials into optical waveguide structures, the cross-talk between waveguides can be reduced enabling denser integration in photonic integrated circuits. In this work we present results of Finite Element Method simulations to optimize the metamaterial-based cladding of the so called e-skid waveguides in order to achieve the longest possible coupling length. We show that e-skid waveguides can have significantly longer coupling length compared to strip waveguides due to reduced skin depth. We optimize the Si based metamaterial structure in terms of number of silicon ridges, period and fill factor of silicon and show that results strongly depend on the chosen surrounding material (air or silicon dioxide).
Keywords: All-dielectric metamaterials, silicon photonics, e-skid waveguides, cross-talk, Finite Element Method
O-band DAC-less PAM-4 generation with a silicon dual-drive Mach-Zehnder Modulator (Student Paper)
Lucas Deniel1, Mathilde Gay2, Diego Pérez-Galacho1,3, Charles Baudot4, Laurent Bramerie2, Oskars Ozolins5, Fréderic Boeuf4, Laurent Viven1, Christophe Peucheret2, Delphine Marris-Morini1
1 Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91120 Palaiseau, France
2 Univ Rennes, CNRS, FOTON – UMR 6082, F-22305 Lannion, France
3 now at : ITEAM research institute, Universitat Politècnica de València, Camino de Vera s/n, 46022, Valencia, Spain
4 ST Microelectronics, 850 rue Jean Monnet, 38920 Crolles, France
5 Networking and transmission Laboratory, RISE AB, Kista, Sweden
4-level pulse amplitude modulation (PAM-4) is the chosen modulation format for next generation optical short-reach data communications such as intra-datacenter communications. On-chip generation of PAM-4 signals is possible using a single dual-drive Mach-Zehnder modulator (MZM). By driving the modulator with two voltage-unbalanced binary signals it is possible to avoid any power hungry electrical digital-to-analog converter (DAC). PAM-4 signal generation at 20 Gbit/s is demonstrated using a silicon dual-drive MZM in the O-band. A bit error rate (BER) of 3.810-3 is measured at -6 dBm input power.
Keywords: Silicon, Mach-Zehnder modulator, PAM-4, O-band, DAC-less.
Tunable optoelectronic oscillator based on silicon micro-ring resonator (Student paper)
Phuong T. Do1, Carlos Alonso-Ramos2, Xavier Le Roux2, Laurent Vivien2, Isabelle Ledoux1, Eric Cassan2
and Bernard Journet1
1 LPQM (CNRS UMR-8537) École normale supérieure Paris-Saclay, Centrale Supelec, Université Paris-Saclay,
61 avenue du Président Wilson, 94235 Cachan Cedex, France
2 C2N (CNRS UMR-9001), Univ. Paris-Sud, Université Paris-Saclay,10 Boulevard Thomas Gobert, 91120
A new silicon optoelectronic oscillator (OEO) system is proposed and experimentally demonstrated. The proposed OEO, generates the microwave signal by beating the un-modulated and amplitude-modulated versions of the same laser source. The drop port of a silicon micro-resonator is used to select one of the side band lobes generated by the amplitude modulation, thus serving as frequency selective element in the OEO. In this scheme, the microwave frequency generated is determined by the wavelength separation between the laser and the ring resonance. Thus, seamless microwave frequency tuning can be achieved just by sweeping the wavelength of the laser source. A proof-of-concept demonstration is implemented, experimentally showing microwave frequency generation in the range from 5.9 GHz to 18.2 GHz.
Keywords: Silicon photonic, function integration, silicon microring resonator, optoelectronic oscillator.
Development of high index contrast waveguide platform for fluorescence based optical nanoscopy
Firehun Tsige Dullo1, Øystein Ivar Helle1, David Andre Coucheron1, Marcel Lahrberg1, Jean-Claude Tinguely1 and Balpreet Singh Ahluwalia1*
1 Department of Physics and Technology, UiT, The Arctic University of Norway, Klokkargådsbakken N-9019, Tromsø, Norway
High-index contrast (HIC) based photonics integrated circuit platforms have played a vital role in integrating complex optical components in a small footprint. Here, we report chip-based nanoscopy (CbN) by using HIC waveguide platforms. In CbN, the waveguide chips generate, deliver and steer the laser illumination pattern. By using a nanoscopy technique of single molecule localization, we demonstrate CbN with a resolution of 50 nm. Furthermore, we show that chip-based structured illumination microscopy can overcome the 2 resolution enhancement set by the objective launch in conventional linear SIM.
Keywords: High index contrast, Silicon nitride, optical nanoscopy, super-resolution microscopy.
Integrated single-mode frequency converter based on KTP
Christof Eigner1, Laura Padberg1, Matteo Santandrea1, Harald Herrmann1,
Benjamin Brecht1, Christine Silberhorn1
1Paderborn University, Department of Physics – Integrated Quantum Optics – 33098 Paderborn – Germany
Tel: +495251 60 5896, Fax: +495251 60 5886, e-mail: firstname.lastname@example.org
Waveguide circuits play a key role in modern integrated optics and provide an appealing approach to scalability in quantum optics. We report on periodically poled waveguides in z-cut potassium titanyl phosphate (KTiOPO4 or KTP), a material that has recently received growing interest due to its unique dispersion properties. We fabricated channel waveguides guiding in a single-mode regime around 800 nm. In combination with a periodic poling the devices allow for type-II second harmonic generation / sum frequency generation from 801 nm to 400.5 nm with high efficiency of 2.3%/Wcm2. Low attenuation values of 1.2 dB/cm (1.7 dB/cm) we determined at a wavelength of 800 nm for TE (TM) polarization. Temperature dependence of the second harmonic process we found to be 35 pm/K. The low temperature dependence and high nonlinear conversion efficiency make our waveguides ideally suited for future operations in classical nonlinear integrated optics and integrated quantum networking applications.
Keywords: integrated optics, quantum optics, waveguides, frequency conversion, material processing
Ultrathin SOI strip-loaded resonators: Permanent mitigation of losses using UV light
Mher Ghulinyan1, Gioele Piccoli1,2, Martino Bernard1,3 and Georg Pucker1
1 Centre for Materials and Microsystems, Fondazione Bruno Kessler, I-38123 Trento, Italy
2 University of Trento, I-38123 Trento, Italy
3 Department of Information Engineering, University of Brescia, I-25123 Brescia, Italy
The performance of integrated micro-photonic devices relays majorly on the mitigation of optical losses. Here, we report on the design, fabrication and characterization of Silicon Nitride strip-loaded guiding optical components realized on a sub-30 nm ultra-thin SOI platform . Omitting physically etched boundaries within the guiding core is known to suppress significantly the scattering loss, as shown by us previously for Si3N4 devices. Here, contrary to expectations, the freshly fabricated SOI devices suffer large losses of 5 dB/cm. We first relate this to the absorption by free carriers, which accumulated under the positively charged Si3N4 loading layer, and successively, demonstrate that exposures to UV light neutralize progressively and permanently Si3N4’s bulk charge, associated with diamagnetic K+ defects. As a result, a net decrease of electron concentration in the SOI layer reduces the propagation losses down to 0.9 dB/cm. We performed accurate cavity linewidth measurements showing how the intrinsic cavity Q’s boost from 70,0000 up to 500,000 after UV illumination. Our results may open routes towards engineering of new functionalities in photonic devices, unveil the origin of induced optical nonlinearities in Si3N4/Si micro-photonic systems, as well as envisage possible integration of these with standard as well as ultrathin SOI electronics.
Keywords: Silicon-on-insulator, silicon nitride, waveguides, optical loss, ultraviolet light.
Alignment-tolerant taper design for transfer printed III-V-on-Si devices (Student paper)
Bahawal Haq 1;2, Gunther Roelkens 1;2
1Photonics Research Group, Department of Information Technology, Ghent University – imec
iGent, Technologiepark-Zwijnaarde 15 – 9052 Ghent – Belgium
2Center for Nano- and Biophotonics (NB-Photonics), Ghent University – Ghent – Belgium
In this paper, we present the design of a 1.0 m misalignment-tolerant taper for the evanescent coupling of light in a III-V-on-silicon opto-electronic device realized on an SOI waveguide platform with 400 nm thick Si device layer. The designed taper is also fabrication tolerant and is suitable for the transfer-printing-based integration of pre-processed III-V devices on Si photonics waveguide circuits. The design procedure is flexible and can take into account the limitations in critical dimensions imposed by the fabrication process.
Keywords: III-V/Si integration, Transfer Printing, Adiabatic taper
Refractive index tunability and switching with vanadium dioxide on silicon
waveguides Student Paper
Vadivukkarasi Jeyaselvan 1, Anand Pal 2, P. S. Anil Kumar 2, Shankar Kumar Selvaraja 1
1Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore, India
2Department of Physics, Indian Institute of Science, Bangalore, India
In this paper, we demonstrate a vanadium dioxide (VO2) based absorption modulator on silicon-on-insulator platform. The optical modulation is achieved by thermally tuning (local) the refractive index (phase) of VO2.
We use a micro-ring resonator for optical modulation in our experiment. The device shows a low insertion loss of 1.48 dB and high extinction ratio change of 16 dB. The transition spectrum analysis yields an approximately 1.2 change in refractive index across the transition. Mach-Zehnder configuration is used to analyze the switching performance of the device.
Keywords: optical modulator, vanadium dioxide, phase change material, ring resonator, Mach-Zehnder interferometer
Cylindrical Integrated Optic Resonant Reflection (Student Paper)
Erika Koussi, Hugo Bruhier, Isabelle Verrier, Nicolas Crespo-Monteiro, Olivier Parriaux, Yves Jourlin
Lyon University at Saint-Etienne, CNRS, Institut d’Optique Graduate School,
Laboratoire Hubert Curien UMR 5516, 42023 Saint-Etienne, France
A sol-gel TiO2/photoresist two-layer is coated at the inner wall of a fused silica tubular cylinder by controlled pulling. The photosensitive layer is exposed to the interferogram generated by a radial phase-mask centred on the cylinder axis illuminated by an axial UV beam. This results in a photoresist grating having an integer number of lines parallel to the axis. A metal cone of 90o apex is introduced in the tube; it reflects a collimated IR axial beam which it transforms into a cylindrical wave incident perpendicularly onto the TiO2/resist waveguide grating. The spectral component satisfying the mode coupling synchronism condition experiences a holistic resonant reflection over 2 which the cone redirects to a detection unit. The presentation describes the design of the cylindrical functional structure and demonstrates the occurrence of TE and TM resonant reflection experimentally.
Keywords: Grating waveguide, mode coupling, resonant reflection, cylindrical wave.
Phase-matching unsensitive to waveguide parameters variations in χ2 based nonlinear integrated optics devices
Maxim Neradovskiy, Hervé Tronche, Elizaveta Neradovskaia, Martin Richter, Ulrich Kuhl,
Pierre Aschiéri, Florent Doutre, Tommaso Lunghi, Pascal Baldi, and Marc P. De Micheli
Université Côte d’Azur, CNRS, Institut de Physique de Nice, 06100 Nice, France
Using Soft Proton Exchanged (SPE) waveguides in lithium niobate for nonlinear interactions combining quasiphase-matching and modal phase-matching allowed us to precisely determine the index profile of SPE waveguides and show that they can present phase-matching configurations unsensitive to waveguide parameters variations.
Numerically we have shown that this property is due to the particular index profile of the SPE waveguides and that it can be extended to other material combinations as soon as they present similar index profiles.
Keywords: nonlinear optics, unsensitive phase-matching, waveguide index profile, overlap.
New Resonance Behavior based on Bound States in the Continuum in a Silicon Photonic Waveguide Platform
Thach G. Nguyen, Guanghui Ren, Steffen Schoenhardt, Markus Knoerzer, Andreas Boes, and
School of Engineering, RMIT University, Melbourne,VIC3001, Australia
A new type of resonance in silicon photonics is demonstrated, which is achieved by coupling between a continuum of TE slab modes to a discrete TM mode of a silicon ridge to create a single sharp resonance. Theoretical description of the phenomenon and experimental results are presented.
Keywords: photonic integrated circuits, silicon photonics, resonator, bound states in the continuum
Grating assisted contra-directional filters with high rejection ratio in silicon
nitride rib waveguides (Student Paper)
Xiaomin Nie 1;2, Nina Turk 1;2, Zuyang Liu 1;2, Roel Baets 1;2
1Ghent University – imec, Photonics Research Group, Technologiepark 126, B-9052 Ghent, Belgium
2Center for Nano- and Biophotonics, Ghent University, Belgium
In this work, we report an on-chip filter that has a high rejection ratio and an unlimited free spectral range (FSR) on the red side of the stop/pass band. This filter is based on a grating assisted contra-directional coupler and is fabricated with one step electron-beam lithography on a silicon nitride rib waveguide platform. This type of filter is able to couple the light into a bus waveguide contradirectionally, instead of reflecting the light back to the input as in the case of a Bragg reflector. We experimentally demonstrate a filter with a stop band centered at 789 nm with an average rejection ratio of 43 dB and bandwidth around 1.7 nm.
Keywords: on-chip filter, silicon nitride, grating assisted contra-directional coupler, e-beam lithography.
Reduced Timing Jitter in a Hybridly Mode-Locked Semiconductor Laser due to an Increased Modulation Curvature (Student Paper)
Lars Nielsen, Martijn J. R. Heck
Aarhus University – Department of Engineering, Finlandsgade 22, 8200 Aarhus N, Denmark
Low-noise microwave oscillators are essential to several applications, and mode-locked lasers are good candidates for the realization of these. The total timing jitter of an actively mode-locked laser has previously been shown to be inversely proportional to the modulation curvature of the driving signal. This paper presents the first numerical study on the timing jitter in a semiconductor hybridly mode-locked laser, when the reverse bias voltage of the saturable absorber is driven with different modulation curvatures. It is confirmed that also for these lasers, the total timing jitter scales reciprocally with the modulation curvature. Thus, according to the numerical model, the performance of a mode-locked laser based oscillator will improve by increasing the bandwidth of the signal driving the saturable absorber. Coupled opto-electronic oscillators, as well as clock extraction from pulse trains in optical time division multiplexing systems, can improve from this.
Keywords: Mode-locked lasers, hybrid mode-locking, timing jitter, photonic integrated circuits, laser modelling,
Optimisation of corrugation-free Rb-exchanged waveguides in periodically poled KTiOPO4 (Student paper)
Laura Padberg 1, Matteo Santandrea 1, Raimund Ricken 1, Christof Eigner 1, Christine Silberhorn 1
1Department of Physics – Integrated Quantum Optics, Paderborn University, 33098 Paderborn, Germany
Waveguide circuits are a key component for modern integrated optics and scalable quantum optics applications.
In this paper we present our studies on rubidium-exchanged waveguides fabricated in periodically poled bulk potassium titanyl phosphate (KTiOPO4 or KTP). We show that face polarity affects the diffusion mechanism of the rubidium, thus leading to different waveguide depths depending on the exposed face polarity. Simulations show that this effect could significantly reduce the efficiency of a process. Employing energy dispersive X-ray spectroscopy (EDX), we analysed a set of waveguides fabricated with different production parameters. Based on this result, we optimised the fabrication process and were able to produce waveguides with reduced corrugations.
Keywords: nonlinear optics, integrated optics, quantum optics, material processing, waveguide fabrication
New Resonant Diffraction Phenomenon from Silicon Grating Waveguide
Olivier Parriaux, Yves Jourlin
Lyon University at Saint-Etienne, CNRS, Institut d’Optique Graduate School,
Laboratoire Hubert Curien UMR 5516, 42023 Saint-Etienne, France
The excitation of a grating waveguide mode from a high-index incidence medium by means of the +1st and -2nd diffraction orders of the grating in the neighbourhood of the -1st order Littrow condition causes a lossless 100% isolation switching between the propagative 0th and -1st reflected orders upon a wavelength or angular scan under the condition that all orders in the low-index transmission medium are evanescent. This purely reflective diffractive effect only occurs if the excited mode effective index is larger than 3. Considering that the waveguide is corrugated, silicon and related microstructuring technologies is thus the adequate implementation material. This new resonant diffraction effect can be used for wavelength and angular control, and biochemical sensing.
Keywords: Grating waveguides, resonant diffraction, mode coupling, silicon photonics
Highly-efficient grating couplers based on transfer-printing technology
Fabio Pavanello 1;2, Grigorij Muliuk 1;2, Gunther Roelkens 1;2
1Ghent University – imec, Technologiepark 15, 9052 Ghent, Belgium
2Center for Nano- and Biophotonics, Ghent University, Belgium
We propose a new approach that allows highly efficient fiber-to-chip coupling using transfer-printing technology.
The novelty of the approach relies on the integration of a mirror between a top (source) grating coupler circuit and a bottom (target) photonic integrated circuit (PIC) and on a wide directional coupler to transfer the light between the two waveguide layers before tapering the waveguide to single mode widths. We propose an apodized, partially etched, grating coupler integrated with a directional coupler implemented in amorphous Si, while a crystalline 220nm Silicon-on-Insulator (SOI) platform is used for the target PIC. We achieve a
simulated 2D coupling efficiency of 96.2% (-0.17 dB) with a 1 dB bandwidth of 45 nm. The bandwidth takes into account the broadband directional coupler, which is very compact. The alignment tolerance along the direction orthogonal to the light propagation is better than +/- 2 μm to achieve an insertion loss penalty lower than 1 dB, which is well within reach with transfer printing.
Keywords: Silicon photonics, grating couplers, transfer-printing technology.
Numerical Investigation of Silicon Nitride-based Frequency Comb in the Radio over Fiber System (Student Paper)
Shahryar Sabouri 1, Mojtaba Sohrabi 2, Mircea Catuneanu 1, Dirk Plettemeier 2, Kambiz Jamshidi 1
1 Integrated Photonic Devices Group, 2 Chair of Radio Frequency and Photonics Engineering, Technische Universität Dresden Dresden, Germany
To generate carriers with high frequencies in the central office, an integrated frequency comb using optical solitons is studied. Both single and double solitons in a silicon nitride microring cavity are investigated numerically for this purpose. The parameters required for the single solitons with the frequency spacing equal to the resonator free spectral range (FSR) and power suppress ratio of -2dB and double solitons with the frequency spacing of multiple (1-3) resonator FSR and power suppress ratio of -1dB is obtained.
Keywords: Solitons, Silicon nitride, Radio over Fiber, Photonic integrated circuits.
Back-illuminated normal-incidence Ge-on-Si photodetectors
David Schmelz1, Martin Steglich1, Kay Dietrich1, Thomas Käsebier1, Uwe D. Zeitner1
1 Institute of Applied Physics, Friedrich-Schiller-Universität, Albert-Einstein-Straße 15, 07745 Jena – Germany
Backside illumination enables an increase in photoactive area and numerical aperture of Ge-on-Si photodetectors for SWIR applications. The transparency of silicon in the infrared range (λ > 1.1 μm) allows a nearly lossless propagation of incoming light through the Si substrate and also an application of optical microstructures on the rear side of the Si substrate. Moreover, an aluminium front contact covering the whole top area serves as a mirror which extends the optical propagation of the detectable SWIR light through the absorbing layers and hence increases the quantum efficiency. We developed back-illuminated Ge-on-Si photodiodes to verify these concepts. Especially the usage of light trapping structures shows great potential. Among the different microstructures we chose black silicon (b-Si) as a promising light trapping candidate. After the fabrication,
photodiodes with different configurations were evaluated. The obtained results show a strong increase of the quantum efficiency due to both, the existence of an Al mirror and the application of b-Si.
Keywords: Ge-on-Si, pin-photodiode, Backside illumination, SWIR, Microstructures, Black silicon
Thermal regime of femtosecond writing for a phosphate glass (Student Paper)
N.N. Skryabin1,2,*, D.V. Khudyakov3, S.K. Vartapetov3, and I.V. Mel’nikov1
1 Moscow Institute of Physics and Technology, Dolgoprudny, 141700 Moscow Region, Russian Federation
2 Quantum Technologies Centre, M. V. Lomonosov Moscow State University, Moscow, Russian Federation
3 Physics Instrumentation Center of the GPI RAS, Troitsk, Moscow Region, Russian Federation
We report on peculiarities of femtosecond writing in phosphate glass at a thermal regime in the sense of two different types of written tracks demonstrated. The operation diagram is shown for a wide range of laser repetition rates (< 2 MHz) and pulse energies (< 400 nJ). In addition, we explain the mechanism of formation of periodic bubble-like structures and present some discussions for a thermal regime in other materials.
Keywords: Femtosecond-laser writing, refractive index, thermal regime, phosphate glass.
Development of a Portable Optical Time Domain Reflectometer System in Photonic Integration Technology
Stanisław Stopiński, Krzysztof Anders, Sławomir Szostak and Ryszard Piramidowicz
Warsaw University of Technology, Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw, Poland
In this work we present and discuss a concept of an integrated optical time domain reflectometer realized in indium phosphide generic integration technology. The proof-of-the-concept chip has been designed, manufactured and tested with respect of applicability in real measuring systems. In general, the correctness of the proposed approach has been confirmed, simultaneously indicating necessary modifications of the design. As a result, the optimized variants of the photonic integrated circuit have been proposed.
Keywords: optical time domain reflectometer, application specific photonic integrated circuit, generic integration technology, indium phosphide
Silicon Waveguide Wavelength-selective Switch Using Cascaded Microring Resonators and Thermo-optic Phase Shifters
Takuya Toma1, Yuya Shoji1,2, Tetsuya Mizumoto1
1 Department of Electrical and Electronic Engineering, Tokyo Institute of Technology,
2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8550 – Japan
2 Laboratory for Future Interdisciplinary Research of Science and Technology,Tokyo Institute of Technology,
2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8550 – Japan
A wavelength selective switch is fabricated for routing wavelength channels in a wavelength division multiplexing network. The device uses a Mach-Zehnder interferometer configuration incorporating wavelength selective phase shifters, which are composed of cascaded microring resonators and waveguide thermo-optic phase sifters. The fabricated device works as a hitless wavelength selective switch with on/off switching ratios of 23 and 20 dB in two wavelength channels of 1532.5 and 1536.7 nm, respectively.
Keywords: silicon photonics, wavelength selective switch, Mach-Zehnder interferometer, microring resonator
GaAs-based gain waveguides with U-bend architecture enabling low loss and high yield hybrid integration on silicon photonic circuits (Student Paper)
Heidi Tuorila1, Jukka Viheriälä1, Nouman Zia1, Matteo Cherchi2, Timo Aalto2, Mircea Guina1
1 Optoelectronics Research Centre, Physics Unit, Tampere University, 33101 Tampere, Finland
2 VTT Technical Research Centre of Finland, Espoo 02044, Finland
We present a U-bend design for traveling wave III-V gain devices, such as semiconductor optical amplifiers and laser diodes. The design greatly simplifies the butt-coupling between the III-V chip and silicon-on-insulator photonic circuit by bringing the I/O ports on one facet. This removes the need for precise dimension control otherwise required for 2-side coupling, therefore increasing the yield of mounted devices towards 100%. The design, fabrication and characterization of the U-bend device based on Euler bend geometry is presented. The losses for a bend with a minimum bending radius of 83 μm are 1.1 dB. In addition, we present an analysis comparing the yield and coupling losses of the traditionally cleaved devices with the results that the Euler bend approach enable, with the final conclusion that the yield is improved by several times while the losses are decreased by several dB.
Keywords: hybrid integration, III-V, semiconductor optical amplifiers, silicon-on-insulator, coupling losses
Building blocks for mid-IR programmable light source based on GaSb-based amplified spontaneous emission sources and μm-scale Silicon-on-Insulator waveguide photonics
Jukka Viheriälä1, Matteo Cherchi2, Heidi Tuorila3, Nouman Zia3, Eero Koivusalo3, Samu-Pekka Ojanen3,
Pentti Karioja2 and Mircea Guina3
1 Faculty of Natural Sciences and Engineering, Tampere University, 33720 Tampere, Finland
2 VTT Technical Research Centre of Finland Ltd, Finland
3 Optoelectronics Research Center, Physics Unit, Tampere University, 33720 Tampere, Finland
Industrial and environmental sensing applications require compact, robust and cost effective mid-IR light sources for multiline spectroscopy. An essential feature of such source is the ability to generate multiple-emission lines on demand, i.e. in a programmable fashion. Building blocks for an integrated programmable light sources operating 2 to 3 μm wavelength band are presented. Our approach is based on μm-scale Silicon-on-Insulator technology and GaSb-based quantum well broadband emitter demonstrates. In particular, we focus on presenting state-of-the-art developments of amplified spontaneous emission sources emitting within 2 μm to 2.65 μm quantum-wells and present their application as semiconductor optical amplifiers. Progress towards emission at
3 μm using GaInAsSb/AlGa(In)AsSb quantum wells in single-transvers-mode superluminescent LEDs is also discussed. Moreover, performance merits for various circuit elements prepared using micron-scale Silicon-oninsulator
technology are described; these include waveguides with low propagation and bend losses and echelle gratings for wavelength selection.
Keywords: Silicon Photonics, mid-IR, superluminescent diodes, semiconductor optical amplifiers, GaSb-laser,
The Feasibility of Building 1024 & 4096-port Nanosecond Switching for Data Centre Networks Using Dilated Hybrid Optical Switches
Junfei Xia, Minsheng Ding, Adrian Wonfor, Richard V. Penty, Ian H. White
Centre for Photonic Systems, Electrical Engineering Division, Department of Engineering,
University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK.
We propose a new 16×16 butterfly dilated hybrid switch. Recursive dilated Beneš and Clos-4-Beneš architectures based on this achieve a 4dB power penalty floor reduction in a 1024-port switch over existing hybrid schemes. A 4096 port switch is proposed with a 12dB input power dynamic range of a penalty less than 3dB.
Keywords: Integrated optical devices; optical switching; data centre.
Inverse-designed low-loss and wideband polarization-insensitive waveguide crossing Student Paper
Zejie Yu,1,2 Aosong Feng,1,2 Xiang Xi,1 and Xiankai Sun1,*
1Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong
2These authors contributed equally to this work
Polarization-insensitive waveguide crossings are desired because photonic networks usually involve light with different polarizations. Here, we propose a polarization-insensitive waveguide crossing on a 250-nm silicon-oninsulator
platform by using an inverse-design method. In simulation, the designed waveguide crossing can maintain insertion loss below 0.18 (0.25) dB in the wavelength range of 1440‒1640 nm for the TE0 (TM0) mode and achieve the minimal insertion loss as small as 0.08 (0.07) dB at the wavelength of 1550 nm. The crosstalk maintains below −32 dB and −35 dB for the TE0 and TM0 modes, respectively. Experimentally, the fabricated waveguide crossing achieves measured insertion loss less than 0.20 (0.25) dB for the TE0 (TM0) mode with the minimal insertion loss as small as 0.1 dB. The measured crosstalk is below −28 dB and −31 dB for the TE0 and TM0 modes, respectively. Therefore, our proposed waveguide crossing can be widely applied in photonic
integrated circuits to construct photonic systems with the capabilities of polarization control and mode (de)multiplexing.
Keywords: optical devices, integrated photonics, silicon photonics.
Photonic welding points for arbitrary on-chip optical interconnects Student Paper
Zejie Yu, Yang Ma, and Xiankai Sun*
Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong
Achieving low-loss waveguide routing with arbitrary configuration is crucial for both classical and quantum photonic applications. To manipulate light flows on a chip, the conventional wisdom relies on waveguide bends of large bending radii and adiabatic mode converters to avoid insertion losses from radiation leakage and modal mismatch, respectively. However, those structures usually occupy large footprints and thus reduce the integration density. To overcome this difficulty, this work presents a fundamentally new approach to turn light flows
arbitrarily within an ultracompact footprint. A type of “photonic welding points” joining two waveguides of an arbitrary intersecting angle has been proposed and experimentally demonstrated. These devices with a footprint <4 μm2 can operate in the telecommunication band over a bandwidth of at least 140 nm with an insertion loss <0.5 dB. Their fabrication is compatible with photonics foundry processes and does not introduce additional steps beyond those needed for the waveguides. Therefore, they are suitable for mass production of PICs and will enhance the integration density to the next level.
Keywords: optical devices, integrated photonics, silicon photonics.
Broad-band phase-matched multimode waveguides for application to four-wave mixing (Student Paper)
Jianhao Zhang1,2, Carlos Alonso-Ramos1, Laurent Vivien1, Sailing He2, Eric Cassan1
1 Centre for Nanoscience and Nanotechnology (C2N), CNRS, University Paris-Sud, University Paris-Saclay, 91120 Palaiseau, France
2 Centre for Optical and Electromagnetic Research, Zhejiang University, Hangzhou 310058, China
We present a general method to equalize the frequency spacings for application to inter-modal degenerate four-wave mixing in a multimode waveguide. By applying the proposed method, the dispersion of the modes can be controlled allowing flexible phase to frequency and wave vector phase matching (PM) between several propagative modes. Taking advantage of the proposed method, PM can be satisfied over a wide wavelength range, e.g. bridging from telecom wavelength to almost 2 μm. In addition, the reported approach releases new degrees of freedom to tune group velocity dispersion to achieve four-wave mixing in single-mode waveguides for on different material platforms and waveguide thicknesses. We believe that this method has an immense potential for a plethora of all-optical signal processing applications in the telecom range, mid-infrared light generation and Brillouin scattering with selectable phonon energy.
Keywords: Phase-matching, nonlinear processes, dispersion, multi-mode operation, broadband conversion, self-adaptive boundary.
An NbTiN superconducting single photon detector implemented on a LiNbO3 single mode nano-waveguide at telecom wavelength (Student paper)
Julien Zichi1,, Samuel Gyger1,, Mohammad Amin Baghban1,*, Ali W. Elshaari1, Katia Gallo1, Val
1 Department of Applied Physics, Royal Institute of Technology, Albanova University Centre,
Roslagstullsbacken 21, 106 91 Stockholm, Sweden.
The authors contributed equally.
Fiber-coupled superconducting nanowire single photon detectors are a ubiquitous tool for quantum optics experiments as they offer near unity detection efficiency over a broad wavelength range, low dark count rate, excellent time resolution and high saturation rate. Nevertheless, advancing quantum optics experiments and applications beyond the few-photon limit requires large scale integrated systems of quantum sources and detectors. In recent years there has been a tremendous progress with integrating single photon detectors with a variety of photonic platforms. This includes attempts on ion-diffused waveguides in LiNbO3, a non-linear and electro-optic material with widespread use for signal processing, frequency conversion, and quantum optics devices. However the realization of superconducting detectors on single mode waveguides remains elusive. Here we present an NbTiN superconducting single photon detector integrated directly on a LiNbO3 single mode nanophotonic waveguide at telecom wavelength, with a high critical current density and a dark count rate of 3 mHz at 99% of its critical current.
Keywords: SNSPD, lithium niobate integrated optics, integrated detector, NbTiN, lithium niobate-on-insulator.