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We present an integrated photonic correlation filter for the detection of remote HCN gas. We demonstrate sensing of absorption due to HCN using thermo-optic tuning of the drop port transmission spectrum in a silicon waveguide ring resonator., 2020 IEEE Photonics Conference (IPC), September 28 - October 1, 2020, Vancouver, BC, Canada

Subwavelength engineered metamaterial waveguides and devices are considered as fundamental building blocks for the next generation of integrated photonic circuits. Here we present an overview of recent advances in this surging field.

Subwavelength metamaterial structures in silicon waveguides open new degrees of freedom to control on-chip light propagation. They have been applied to many silicon photonic devices such as fiber-chip couplers, waveguide crossings, microspectrometers, ultra-fast optical switches, athermal waveguides, evanescent field sensors, polarization rotators and colorless interference couplers [1]. Here we report a demonstration of a metamaterial coupler and an InAs-on-InP quantum dash buried heterostructure laser optimized for mutual integration by direct facet-to-facet coupling with -1.2 dB coupling efficiency, coupled laser relative intensity noise (RIN) of -150 dB/Hz and 152 kHz linewidth. We further demonstrate the design of multi-line spectral notch filters based on narrow linewidth metamaterial Bragg filters synthesized using the layer-peeling method., 2020 Photonics North (PN), May 26-28, 2020, Niagara Falls, ON, Canada

Absorption spectroscopy is a powerful technique for characterizing remote gas composition where direct interaction with a target it not possible. While dispersive spectroscopy is typically used to acquire a spectrum with which the gas presence is determined, correlation spectroscopy can directly detect such spectral features in a single detection channel. Here we present a novel integrated photonics correlation technique on an integrated photonic platform which uses real-time spectral processing to generate a multiline gas specific detection signal., 2020 Photonics North (PN), May 26-28, 2020, Niagara Falls, ON, Canada

Metamaterial engineered waveguide structures are emerging as fundamental building blocks for integrated photonics. Here we present an overview of our recent advances in this field, including fiber-chip couplers, ultra-broadband beam splitters, nanophotonic waveguides with engineered anisotropy and integrated Bragg filters., 2019 IEEE Photonics Conference (IPC), September 29 - October 3, 2019, San Antonio, TX, USA

We present a correlation spectrometer using a silicon waveguide ring resonator for the identification of molecules in stellar and planetary atmospheres. We tailor the free spectral range of a ring resonator to the vibronic overtones of carbon dioxide in the near infrared. The ring resonator spectrum is modulated via the thermo-optic effect and produces a detection signal unique to carbon dioxide. This spectrometer can be used for real-time remote gas detection and radial velocities of exoplanets in a narrow spectral band., 2019 Photonics North (PN), May 21-23, 2019, Quebec City, QC, Canada

Subwavelength grating (metamaterial) waveguide devices are becoming established as key building blocks for advanced integrated photonic circuits. In this talk we will present an overview of our recent advances in this surging field.

Non-classical light sources that can produce streams of correlated on-demand photons are a central building block for optics based quantum information technologies. There are numerous possible approaches for producing such a light source. One of the most promising is the solid-state single photon source based on a single quantum dot in III-V semiconductors. Utilizing a single InAs quantum dot in an InP nanowire, we previously demonstrated a bright and efficient source for single photons [1] and entangled photon pairs [2] that emits around 950 nm. In order to interface with telecom systems, single photon sources emitting at longer wavelengths are required. A few works have extended the emission to the telecom band using a single InAs/InP quantum dot in a micro-cavity [3-4]. However, improving the source brightness and the extraction efficiency remains a challenging task. In this contribution, by modifying the growth conditions and the pre-growth pattern for an InAs dot in an InP nanowire, we demonstrate a bright light source that emits in the telecom O-band, an important step towards the demonstration of a single photon source.

We report our advances in development of subwavelength engineered structures for integrated photonics. This unique technology allows synthesis of an effective photonic medium with an unprecedented control of material properties, constituting a powerful tool for a designer of photonic integrated circuits. By locally engineering the refractive index of silicon by forming a pattern of holes at the subwavelength scale it is possible to manipulate the flow of light in silicon photonic waveguides. We have demonstrated a number of subwavelength engineered devices operating at telecom wavelengths, including fiber-chip couplers, waveguide crossings, WDM multiplexers, ultra-fast optical switches, athermal waveguides, evanescent field sensors, polarization rotators, transceiver hybrids and colorless interference couplers. The subwavelength metamaterial concept has been adopted by industry (IBM) for fiber-chip coupling and subwavelength engineered structures are likely to become key building blocks for the next generation of integrated photonic circuits. We present an overview of different implementations of these structures in silicon photonic integrated circuits, such as high-efficiency fiber-chip couplers, wavelength multiplexers, microspectrometers, waveguide crossovers, ultra-broadband splitters and mid-infrared waveguide components, to name a few., 2016 Progress in Electromagnetic Research Symposium (PIERS), August 8-11, 2016, Shanghai, China

Subwavelength engineering in silicon photonic integrated circuits is a powerful design tool that allows one to synthesize an effective photonic medium with adjustable refractive index. This creates a new degree of freedom in photonic circuit design. We present an overview of the fundamental concept and its application to address several important practical challenges in the implementation of silicon photonics as a next generation photonics platform for telecom, datacom and sensing. In particular, we report our results in developing highly efficient and broadband fiber-chip couplers for silicon photonic wire waveguides using subwavelength engineered edge coupling structures. We experimentally demonstrate a coupling efficiency of -0.4 dB and polarization independent operation for a broad spectral range exceeding 100 nm for optical fiber with a core diameter of 3.2 μm. For coupling to standard SMF-28 fiber with 10.4 μm mode field diameter we numerically demonstrate a subwavelength engineered overlayer structure composed of SiO2 and Si3N4 which exhibits an overall coupling efficiency exceeding 90%. We have also used our subwavelength structure for coupling experiments with a conventional InGaAsP/InP buried heterostructure laser at λ = 1.3 μm with a measured near field mode size of 2.1 μm×2.8 μm. Peak coupling efficiency is 1.5 dB with 1-dB alignment tolerance of approximately ±1.2 μm horizontally and ±0.8 μm vertically. We further present subwavelength engineered grating couplers fabricated in a single-etch step for the telecom (1.55 μm) and datacom (1.3 μm) wavelengths with efficiencies exceeding -0.5 dB. Further applications that will be discussed include waveguide crossings, microspectrometers, ultra-fast optical switches, athermal waveguides, evanescent field sensors, polarization rotators and colorless interference couplers., 2016 Progress in Electromagnetic Research Symposium (PIERS), August 8-11, 2016, Shanghai, China

Key aspects of the growth of site selected InP nanowires will be discussed, focussing on those relevant to quantum information processing. Parameters including high brightness, narrow linewidth and single photon purity, and a route to integration into planar optical circuits will be discussed., 2016 IEEE Photonics Society Summer Topical Meeting Series (SUM), July 11-13, Newport Beach, CA, USA

We report our recent advances in development of subwavelength engineered dielectric metamaterial structures for integrated photonics., 18th International Conference on Transparent Optical Networks (ICTON), July 10 -14, 2016, Trento, Italy

Subwavelength grating structures with a pitch smaller than the Bragg resonance length can be used for engineering the refractive index in silicon photonic waveguides. We discuss the principles, design, fabrication and applications of subwavelength nanostructures in silicon photonics and review our recent results on fiber-chip coupling structures, surface grating couplers, waveguide crossings, and athermal waveguides with a polymersilicon hybrid core., 16th International Conference on Transparent Optical Networks, ICTON 2014, 6 July 2014 through 10 July 2014, Graz

We report a spatial heterodyne Fourier-transform spectrometer consisting of an array of Mach-Zehnder interferometers (MZI) implemented in silicon microphotonics. Optical path differences between the MZI arms increase linearly along the array, generating a wavelength-dependent interferogram which enables the retrieval of the source spectrum with a single measurement. Optical delays were implemented with Si-wire waveguides arranged in tightly coiled spirals to achieve a high resolution in a reduced footprint. Our spectral retrieval algorithm compensates phase and amplitude errors arising from fabrication imperfections by using a transformation matrix based on the calibration data. A wavelength resolution of 40 pm within a free spectral range of 0.75 nm is demonstrated., 15th International Conference on Transparent Optical Networks, ICTON 2013, June 23-27, 2013, Cartagena, Spain, Series: International Conference on Transparent Optical Networks : [proceedings]

Recently developed subwavelength structures in silicon waveguides are presented. Subwavelength grating photonic structures are discussed along with emerging practical components that exploit the principle of subwavelength refractive index engineering, including polarization-independent athermal silicon waveguides, ultra-broadband and compact multimode interference couplers, fabrication tolerant polarization rotators and interferometer arrays with subwavelength optical delay lines.

A lateral etched-grating process was used to produce singlemode distributed feedback laser diodes at 3.23 μm. The devices are based on InGaAsSb/AlInGaAsSb type-I quantum well active regions grown on GaSb substrates by molecular beam epitaxy. The lasers were used in high-resolution spectroscopy of methane gas near the v 3 , R 7 vibrational absorption transitions.

We demonstrate an ultracompact polarization mode converter based on a silicon-on-insulator waveguide with two longitudinal subwavelength trenches. An extinction ratio of 16 dB at 1.5 μm is achieved for a device length of 10 μm. © 2012 OSA., 2012 Conference on Lasers and Electro-Optics, CLEO 2012, 6 May 2012 through 11 May 2012, San Jose, CA

Our progress in subwavelength structures in silicon waveguides is reviewed. Several practical implementations of subwavelength grating waveguides are discussed, including fibre-chip couplers, waveguide crossings and athermal waveguides. © 2011 IEEE., 8th IEEE International Conference on Group IV Photonics, GFP 2011, 14 September 2011 through 16 September 2011, London

In this paper, athermal subwavelength grating (SWG) waveguides are investigated. Both numerical simulations and experimental results show that a temperature independent behaviour can be achieved by combining two materials with opposite thermo-optic coefficients within the waveguide. SU-8 polymer with a negative thermo-optic coefficient (dn/dT = -1.1×10-4 K -1) is used in our silicon SWG waveguides to compensate for silicon's positive thermo-optic coefficient of 1.9×10-4 K-1. The grating duty ratio required to achieve an athermal behavior is reported to vary as a function of the operating wavelength and the waveguide dimensions. For example, for athermal waveguides of 260 nm in height, duty ratios of 61.3% and 83.3% were calculated for TE and TM polarized light respectively for a 450 nm wide waveguide, compared to ratios of 79% and 90% for a 350 nm wide waveguide. It is also reported that with increasing width, and increasing height, a smaller grating duty ratio is necessary to achieve an athermal behaviour. A smaller fraction of silicon would hence be needed to compensate for the polymer's negative thermo-optic effect in the waveguide core. Subwavelength sidewall grating (SWSG) waveguides are also proposed here as alternatives to high duty ratio SWG waveguides that are required for guiding TM polarized light. Assuming a duty ratio of 50%, the width of the narrow segments for temperature- independent behavior is found by numerical simulations to be 125 nm and 143 nm for TE and TM polarized light, respectively. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE)., Photonics North 2011, May 16-18, 2011, Ottawa, Ontario, Canada, Series: Proceedings of SPIE; no. 8007

A complete instrumentation system for interrogating silicon photonic wire waveguide sensor array chips has been built and demonstrated. The system is designed to read 16 or more photonic wire sensors on a single silicon chip simultaneously and in real time, while delivering sample fluid to the sensors through microfluidic channels fabricated monolithically on the chip. The chip can be inserted into the instrument, automatically aligned with input optics and fluid connection, and be ready for measurement in a few minutes. © 2011 IEEE., 8th IEEE International Conference on Group IV Photonics, GFP 2011, 14 September 2011 through 16 September 2011, London

Type-I interband laser diodes were developed for trace gas sensing applications in the 2–4um wavelength range. The devices were grown by molecular beam epitaxy on GaSb substrates using InGaAsSb/Al(In)GaAsSb active regions. Tunable, single-mode lasers were produced using distributed feedback grating processing or by incorporating Fabry-Perot lasers in an external cavity configuration. Sensitive gas detection was demonstrated using these lasers in tunable-diode laser absorption spectroscopy.

Photonic wire evanescent field (PWEF) sensor chips have been developed for multiplexed label free molecular detection. The sensors are made using 260 nm ×450 nm cross-section silicon waveguides folded into spirals less than 200 μm in diameter, but with an overall sensor length of more than a millimeter. The long propagation length gives a response to molecular binding much better than currently available tools for label-free molecular sensing. These sensors can be arrayed at densities up to ten or more per square millimeter. This talk reviews our ongoing work on the photonic wire sensor chip design and layout, on-chip integrated fluidics, optical coupling, and chip interrogation using arrays of grating couplers formed using sub-wavelength patterned structures. The goal is to develop a commercially viable sensor platform by addressing cost-of-instrumentation, cost per measurement, ease-of-use, and by increasing the number of sensors that can be simultaneously monitored. © 2011 IEEE., 2011 ICO International Conference on Information Photonics, IP 2011, 18 May 2011 through 20 May 2011, Ottawa, ON

We review our work on silicon wire devices designed for evanescent field sensor arrays and ultra-compact dense optical comb filters, both taking advantage of a spiral cavity resonator design. Two sensor array configurations are described, and monitoring of biomolecular binding is demonstrated with a detection limit of 0.3 pg/mm2. On-chip temperature drift compensation is achieved by using a reference resonator. A novel grating coupler using subwavelength structures facilitates the coupling of light between the optical fiber and waveguide chips.

Micro-photonic SOI Mach-Zehnder interferometers were coated with solid-phase micro-extraction materials derived from polydimethylsiloxane to enable sensing of volatile organic compounds of the BTEX class in air. A different coating based on functionalized mesoporous silicates is used to detect lead Pb(II) with a detection limit of < 100 ppb in water.

We report on a new waveguide principle using subwavelength gratings. It is known that diffraction effects are suppressed for waves propagating in materials structured at the subwavelength scale. Subwavelength gratings can create artificial media engineered using microscopic inhomogeneities to enact effective macroscopic behaviour. For the high-index-contrast waveguides, a subwavelength grating can be created by the combination of high-refractive-index and low-refractive-index materials, for example single crystal silicon and amorphous silica in silicon-on-insulator platform. These periodic structures frustrate diffraction provided they operate outside the Bragg condition and behave like a homogeneous medium. In a subwavelength grating (SWG) waveguide with a core consisting of a periodic arrangement of segments (Fig. 1), light excites a Bloch mode, which can theoretically propagate through the SWG waveguide with minimal scattering losses. Unlike other periodic waveguides such as line-defects in a 2D photonic crystal lattice, a subwavelength grating waveguide confines the light like a conventional index-guided structure and does not exhibit optically resonant behaviour.

Optoelectronic devices based on single, self-assembled semiconductor quantum dots are attractive for applications in secure optical communications, quantum computation and sensing. In this paper we show how it is possible to dictate the nucleation site of individual InAs/InP quantum dots using a directed self-assembly process, to control the electronic structure of the nucleated dots and also how to control their coupling to the optical field by locating them within the high field region of a photonic crystal nanoocavity. For application within fiber networks, these quantum dots are targeted to emit in the spectral region around 1550nm.

Silicon photonic wire waveguides have a remarkably high response to surface molecular binding. Evanescent field waveguide sensors based on silicon can be interrogated using Mach-Zehnder interferometers, ring resonators, or by probing surface gratings in a reflection geometry. This paper compares these approaches from a theoretical viewpoint and through recent experimental results, with the goal of defining a path from our existing individual sensors to practical biosensor array chips.

We report a SOI ring resonator biosensor array with 1 reference ring and 4 sensing rings, using WDM as the addressing scheme. On-chip referencing and temperature shift cancellation are demonstrated, and the differential signal shows a low temperature sensitivity of ~ ± 0.8 pm/°C.

Silicon-on-insulator (SOI) is considered the most promising high-index-contrast waveguide platform for fabricating microphotonic devices with high integration density. However, there are fundamental challenges with this waveguide system related to the fixed values of the refractive indices of the constituent materials (Si and SiO 2 ). In this paper, we present a method that can potentially circumvent this limitation by using the sub-wavelength grating effect in SOI waveguides to effectively engineer materials with intermediate refractive indices by standard lithographic patterning. The first implementations of the SWG effect in SOI waveguides are discussed, including our latest results in fiber-chip couplers, anti-reflective and high-reflectivity waveguide facets, mode transformers between waveguides of different geometries, and microphotonic waveguide crossings.

This invited talk presents the evolution of the planar waveguide dispersive devices developed in our laboratory for spatial heterodyne spectroscopy. The basic concepts are introduced and then applied to a Mach-Zehnder interferometer array capable of a resolution of 0.1 nm over a bandwidth of 2.5 nm.

We show by theoretical analysis and experiments on submicrometer silicon-on-insulator channel waveguides that the optical scattering loss of high-index-contrast planar waveguides is modified significantly by a thin-film interference effect, caused by boundary reflections.

This paper reports the progress (design, fabrication and measurement) in label-free biological sensors based on ring resonator technology originally developed for telecommunication. These sensors are made in silicon-on-insulator (SOI), a high index contrast material platform that provides enhanced sensitivity and allows compact waveguide geometries by employing very small bend radii. A double spiral shape allows designing millimetre-long resonator in a compact size (100-150 mum) compatible with spotting technology used for large biochip assays. The detection limit estimated from the resonance shift measurement is ~5 fg of streptavidin adsorbed on the sensor surface functionalised with biotin.

We investigate the growth of positioned InAs/InP quantum dots for incorporation into InP-based photonic crystal microcavities. The optical properties of these quantum dots and the photonic crystal microcavities are described, as well as the effect of a lateral electric field on biexciton binding energy. This system is proposed as a scalable route to single and entangled photon pair sources at telecommunications wavelengths.

We demonstrate a method of canceling the temperature dependence of ring resonator sensors using a double ring configuration. Temperature calibration curves are provided for SOI photonic wire ring sensors with air and SU8 polymer cladding.

We present the novel design of a silicon modulator with low operation voltage of les3 V by employing periodically interleaved pn junctions. Simulations predict that in depletion mode it has a high modulation efficiency of better than 1.5 Vldrcm.

The functionality and performance of many planar waveguide devices, including lasers and optical amplifiers, are critically affected by the reflectivity of the waveguide facets. For high index contrast waveguide devices, the Fresnel reflection at the facet is a significant contribution to the fibre-to-chip coupling loss and the return loss. Currently, the common method to control the facet reflectivity of planar waveguides is the deposition of anti-or high-reflective coatings.

We demonstrate the capability to post-tune a photonic crystal nanocavity resonance without affecting its quality factor via the presence of an evanescently coupling tapered optical fibre. A 3 nm shift is reported.

We demonstrate efficient coupling via a tapered silica nanowire micro-loop to a photonic crystal based nanocavity containing quantum dots, specifically designed for single photon source applications.

We demonstrate efficient coupling via a tapered silica nanowire micro-loop, to a photonic crystal based nanocavity containing quantum dots, specifically designed for single photon source applications.

This paper presents the development of a microspectrometer and a surface plasmon waveguide sensor on a silicon platform derived from the expertise acquired in designing optical telecommunication components.

A silicon-on-insulator based evanescent field sensor using silicon photonic wire waveguides is reported. The unique properties of high index contrast, submicron structures are exploited to enhance electric field magnitude and localization near the sensor surface. The evanescent field sensor is demonstrated in a Mach Zehnder configuration.