The performance of High-Index-Contrast Photonics Platforms for On-Chip Raman Spectroscopy
A. Raza, S. Clemmen, M. de Goede, R. Ali, P. Hua, S. M. Garcia-Blanco, S. Honkanen, J. S. Wilkinson and R. Baets
Photonics Research Group, INTEC Department, Ghent University-imec, Technologiepark—Zwijnaarde, 9052 Ghent, Belgium
Center of Nano and Biophotonics, Ghent University, Belgium
Optical Sciences Group, MESA+ Institute of Nanotechnology, University of Twente, 4617, The Netherlands
Institute of Photonics, University of Eastern Finland, 80101, Finland
Optoelectronics Research Centre (ORC), University of Southampton, Highfield, Southampton, SO17 1BJ, United Kingdom
*Corresponding author: firstname.lastname@example.org\
Various photonic platforms exist that may be suitable for on-chip Raman spectroscopy. Here we compare 4 of them focusing on their intrinsic photon background and their capability for collecting Raman signal from liquid analytes. These two parameters define the complete figure of merit for waveguide enhanced Raman spectroscopy.
Keywords: Raman spectroscopy, Waveguide enhanced Raman sensing, HIC waveguides
On-Chip Vernier Filtering of Colliding Pulse Mode-Locked Laser Coupled with Fabry-Pérot Feedback Cavity via MMI Reﬂector
Mu-Chieh Lo, Robinson Guzmán, and Guillermo Carpintero
Universidad Carlos III de Madrid, Avda. Universidad, 30, 28911 Leganés, Spain
Optical frequency comb spacing multiplication through on-chip Vernier ﬁltering is proposed, based on an InP colliding pulse mode-locked laser coupled with a fractionally matched Fabry-P´erot feedback cavity. These two cavities are deﬁned by and coupled via multimode interference reﬂector. The deliberately set laser-cavity repetition rate and coupled-feedback cavity FSR give rise to Vernier effect whereby the 6th harmonic generation (150 GHz) of fundamental cavity round-trip frequency (25 GHz) is experimentally demonstrated.
Keywords: Laser mode locking, Semiconductor lasers, Cavity resonators
A Compressive Sensing Integrated Fourier Raman Spectrometer
Alan Scott, Hugh Podmore
Honeywell International, 303 Terry Fox Dr., Ottawa, Ontario – Canada
Tel: +01 613 591 7777, Fax: +01 613 591 7789
We have built a novel planar-waveguide Fourier-transform spectrometer (FTS) with several innovative design features to achieve high throughput Raman spectroscopy in a compact layout. This waveguide FTS consists of a set of independent Mach-Zehnder interferometers (MZIs) on a photonic chip. An array of microlenses is bonded to the ‘bottom’ surface of the chip, transforming a normally incident collimated beam into an array of focal spots near the waveguide surface. These micro-beams are deflected using an array of focused ion-beam (FIB) etched 45 degree mirrors into an array of single mode waveguides. Because the features of a Raman spectrum are sparsely distributed in frequency space, we are able to adapt techniques of compressive-sensing (CS) spectroscopy to significantly undersample the interferogram at our chosen bandwidth and resolution. The resulting system reduces the number of waveguides (MZIs) required by a factor of 4 while simultaneously reducing the size of the spectrometer and concentrating the Raman signal in a smaller number of detector pixels for further signal to noise enhancement. Because the interferogram samples are gathered simultaneously, a gated detector can be used to separate Raman peaks from sample fluorescence.
Keywords: Fourier, Raman, Compressive Sensing, Free Space, Microlenses, Silica Waveguides.
Integrated Silicon-on-Insulator AWG Spectrometer with Single Pixel Readout for 2.3 um Spectroscopy Applications
Anton Vasiliev, Muhammad Muneeb, Jeroen Allaert, Roel Baets
and Günther Roelkens
Photonics Research Group, Ghent University-imec and
Center for Nano- and Biophotonics
echnologiepark-Zwijnaarde 15 – 9052 Ghent – Belgium
Tel: +3293314815, e-mail: email@example.com
A compact and cheap mid-infrared spectrometer is realized by integrating a Silicon-on-Insulator (SOI) Arrayed Waveguide Grating (AWG) spectrometer operating in the 2.3 µm wavelength range with a high performance photodiode. The AWG has twelve output channels with a spacing of 225 GHz (4 nm) and a free spectral range (FSR) of 3150 GHz (56 nm), which are simultaneously collected by a single, transistor outline (TO)-packaged extended InGaAs PIN photodiode. The response of each AWG channel is discerned by time-sequentially modulating the optical power in each output channel using integrated Mach-Zehnder based (MZI) thermo-optic modulators with a π-phase shift power consumption of 50 mW. The photonic chip is interfaced using off-the-shelf electronic components and a standard 9/125 single-mode ﬁber. The response of the AWG is limited to one FSR using a 50 nm Full Width Half-Maximum (FWHM) bandpass interference ﬁlter. Using 31 µW optical power in the ﬁber, the absorption spectrum of a 0.5 mm thick polydimethylsiloxane sheet (PDMS) is sampled and compared to a benchtop spectrometer to good agreement.
Keywords: integrated spectrometer, silicon photonics, arrayed waveguide grating, mid-infrared spectroscopy
Integrated Al2O3:Yb3+ Microring Laser for On-Chip Active Sensing in an Aqueous Environment
Michiel de Goede, Lanthian Chang, Meindert Dijkstra, Sonia M. García-Blanco Optical Sciences Group, MESA+ Institute for Nanotechnology
University Twente, P.O. Box 217
7500 AE Enschede, The Netherlands
Tel: +31 53 489 2640, e-mail:firstname.lastname@example.org
This paper presents an integrated on-chip Al2O3:Yb3+ microring resonator laser that operates in an aqueous environment. By varying the refractive index of the bulk cladding, the lasing wavelength can be tuned, allowing this device to operate as an active refractive index sensor. In this manner, the lasing modes could be tuned over 15 nm with a sensitivity of 590 nm/RIU. In combination with the wavelength resolution of the detector (100 pm), a limit of detection of 1.5×10-4 RIU was achieved. The intrinsic limit of detection was not determined due to the incapability of measuring the laser linewidth. This work demonstrates the viability of realizing very sensitive, laser-based active sensors in an aqueous environment on the Al2O3:Yb3+ material platform.
Keywords: Al2O3:Yb3+, laser, microring resonator, sensor.