The last 36 years has seen a steady increase in the deployment of photonic integrated components. Over most of this history, the development of integrated photonic systems in both III-V and Group IV materials has been driven by the needs of fibre optic systems – driven primarily by the properties of the transmission media (single-mode vs multi-mode fibre, fibre gain, etc). Today, photonic integration is increasingly driven by the unique properties of high-performance electronic-photonic interfaces. The low-capacitance, low-energy, high-bandwidth density of photonic integrated systems is now driving optical interconnection into board-scale, chip-scale, and intra-chip photonic systems. Here, we consider new applications ranging from (1) deep learning systems and other data intensive classical compute applications, (2) optically addressed quantum computing fabrics – with tremendous progress being made today in the area of trapped-ion quantum computing, and (3) next-generation brain-computer interfaces where photonics may play an important role in massively parallel signal detection.

As the demands and forms of computers evolve, new hardware is needed to realize different types of computing interfaces. Foundry silicon photonics leverages the maturity of microelectronics manufacturing to fabricate photonic integrated circuits. Today, silicon photonics is mostly used in the short-wave infrared spectrum for fiber optic communication. I will discuss how foundry silicon photonics in the visible spectrum can be an enabling technology for future computing, addressing applications such as displays, neural implants, and quantum computing.

Optical waveguides which are highly transparent to blue and ultraviolet light are critical for a range of photonic integrated circuit (PIC) applications in sensing and quantum timing. At short wavelengths, propagation loss is heavily dependent on sidewall roughness, which is largely determined by lithography and etching processes. We evaluate the effectiveness of multipass e-beam lithography (EBL) in producing low-roughness hydrogen silesquioxane (HSQ) masks, establish the effect of multipass EBL on optical loss in the visible regime, and use our optimised HSQ masking process to fabricate high-confinement single-mode alumina waveguides with propagation losses down to 1.0 dB/cm at 450 nm.

Near-zero-index (NZI) media offers fascinating properties in engineering light-matter interactions. However, the realization of integrated photonics NZI technologies relies on photonic crystals suffering from spatial dispersion and radiative losses. Our work discusses the radiative properties of Dirac-cone metamaterials, considering both the design challenges and the opportunities arising from it. In general, we discuss how designing radiative losses empowers novel forms of dissipation engineering. It allows for a pure silicon photonics implementation of generalized coherent perfect absorption (CPA) effects in classical and quantum photonic networks.

We present two novel topologies of subwavelength grating (SWG) waveguides: the bricked-SWG and the evanescently-coupled-SWG. The bricked topology enables accurate control of waveguide anisotropy while maintaining the index and dispersion engineering advantage intrinsic to SWG waveguides. The evanescently-coupled-SWG allows unprecedented control of the strength of the modal perturbation in waveguide Bragg gratings and nanophotonic antennas. Both topologies leverage a Manhattan-like pattern, with pixel sizes compatible with deep-uv lithography. Our recent results will be discussed, focusing on polarization-independent multimode interference couplers for the O and C bands and a millimeter-long narrow-beam steerable optical antenna array with angular divergence of only 1.8o×0.2o.

We introduce the emerging area of programmable integrated photonics highlighting the operation principles, basic component and subsystem arrangements and fabrication technologies. We describe the main present and future applications of this tecchnology.

Micro- and nano-fabrication allow new optical systems well beyond previous conventional optics. These possibilities cause us to think of optics quite differently. One approach uses “circuits” with topologies and configuration algorithms. Some such topologies support algorithms allow rapid self-configuration, adapting automatically, such as undoing scattering between multiple overlapping beams. Other approaches, such as inverse design, allow almost arbitrarily complex structures. Such different optics need new theoretical approaches and results, giving new scalings, limits and bounds. This talk will summarize work on optical circuits for applications, in computing, communications, and sensing, and new fundamental directions in understanding limits to optical systems.

In accordance with growing scientific interests in nanoplasmonic structures, along with the increasing ability to fabricate them using proper nanotechnologies, and current interest in nonlocal optical responses, first, we have developed a methodology to incorporate nonlocal optical responses, described with a simple hydrodynamic model, into the numerical Fourier modal method (FMM) technique, to enable broadening of the simulation portfolio of such physical phenomena in plasmonic nanostructures. It is generally accepted that nonlocal interactions are most pronounced on structures with nanometer unit sizes and affect the shape of spectral functions of characterizing quantities in the resonance region. We have relied on our previous profound experience, mainly with the periodic (for one-dimensional - 1D and two-dimensional - 2D cases) extensively to various rather complex problems. Here, based on this experience, we have newly incorporated the nonlocal-response approximation into the periodic FMM technique, described with a proper hydrodynamic model, showing in several examples that this implementation is capable of numerically analyzing periodic plasmonic systems, such as nonlocal periodic multilayers and resonant gratings. Secondly, for some simple structures it is possible to find analytical solutions which can then be used to build semi-analytical approaches for the analysis of some more complex structures. Thus the second part is focused on the analytical description of nonlocal manifestations of both a planar metal layer and a bilayer, using the transfer matrix approach.

Erbium-doped fiber amplifiers have revolutionized long-haul optical communications and laser technology. Erbium ions could provide a basis for efficient optical amplification in photonic integrated circuits. We demonstrate a Si3N4 photonic integrated circuit–based erbium amplifier reaching > 100 mW output power and > 30 dB gain – comparable with commercial fiber amplifiers. Moreover, we will show that endowing Si3N4 photonic integrated circuits with Erbium-based optical gain opens the door to the miniaturization of high-performance fiber-based lasers on a chip.

Hybrid integrated diode lasers offer a robust and small-sized solution for applications in telecommunications, quantum optics and metrology due to their wide tunability and ultra-narrow linewidth. Here, we present the fabrication, packaging and successful operation of the first fully integrated, aluminum oxide (Al2O3) based, hybrid diode laser operating at 405 nm. Low-loss, high-confinement waveguides are fabricated with a measured propagation loss of only 2.8 ± 0.3 dB/cm. The hybrid laser consists of a GaN SLED butt-coupled to an Al2O3 feedback circuit comprising of two microring resonators that form a frequency selective Vernier filter. The chip assembly is packaged in a hermetically sealed, butterfly housing for optimal performance and durability. The laser shows a maximum output power of 0.74 mW and is tunable over the entire gain bandwidth of 4.4 nm.

We will present our design strategies adopted to boost the performance of heterogeneously integrated III-V-on-Si quantum well lasers for optical communications. For that, we will revisit our recent work on the co-integration of dual-ring widely tunable lasers with semiconductor optical amplifiers on a silicon photonic platform. Also, we will present a nanosecond-tunable capacitive III-V-on-Si distributed feedback laser able to continuously tune its emission wavelength over a 10 GHz span in only 2 ns. Finally, we will show our latest results on low-k distributed feedback lasers with backside sample gratings, showing a high output power and a low laser linewidth.

We demonstrate a hybrid GaSb/Si3N4 Vernier laser in an edge-coupled configuration emitting around 2.55 µm, consisting of a GaSb-based reflective semiconductor amplifier, and a reflective Si3N4 circuit, consisting of two resistively tunable ring resonators in a loop mirror towards Vernier type operation. The hybrid laser exhibited a threshold current of 190 mA, and a maximum output power of 6.4 mW around 325 mA injection current. Moreover, the hybrid laser showed a broad tuning range of 170 nm, with an access to wavelengths from 2474 nm to 2644 nm, and a > 1 mW output power across the whole tuning band.

We present for the first time transfer printable GaSb laser diode and semiconductor optical amplifier coupons. Device coupons show excellent device characteristics with little or no penalty associated to specific integration features required by transfer print process. Transferring of devices on silicon substrate containing a waveguide structure is shown and preliminary results from transferred devices show CW lasing around 2 µm wavelength and light coupling to a waveguide on integrated photonic circuit. The fabrication methodology enables a wide variety of GaSb devices towards highly integrated photonics applications in environmental sensing, bio marker identification and industrial monitoring.

We demonstrate the first fully on-chip electrically-pumped laser-integrated quantum photonic source, which consists of a laser cavity, an InP gain section, and a Vernier filtering stage. This sub-millimeter-sized hybrid chip generates high-quality, low-noise (CAR ~80) entangled photon states with a remarkably high pair detection rate (~620 Hz) over four resonant modes within the C-band. We confirmed the realization of high-dimensional entangled states with fidelity of ~ 0.99 and visibility of ~ 96%. This fully integrated, practical, and field-deployable quantum light source brings scalability to applications ranging from quantum processing circuits, quantum internet to quantum satellite systems.

This conference presentation was prepared for Photonics West 2023.

We will provide a hardware update on our progress towards building a fault-tolerant quantum computer based on photonics. In addition, we will discuss our present-day programmable machines, available over the cloud, that serve as key milestones on the path to this goal. These include Borealis, our cloud-deployed photonic quantum computer capable of quantum computational advantage.

In this paper, we propose and design a photonic integrated circuit capable of handling multiplication of a 64-long vector and a 64x64 matrix for vector-matrix multiplication acceleration in optical domain. With close integration of the photonic integrated circuit with a co-designed electronic integrated circuit, we demonstrated acceleration of Ising model and achieved over 800x speedup compared to a traditional GPU.

III-V semiconductors present a viable solution for many nonlinear optics applications such as on-chip wavelength conversion, all-optical signal processing, environmental sensing, and quantum information. In this talk, we will discuss our recent contributions in the field of nonlinear photonic devices based on III-V semiconductors.

We cover recent work on photo-induced second order nonlinearities in silicon nitride microresonators. We show that, like in waveguides, all-optical poling occurs in resonators via the photogalvanic process, resulting in high efficiencies owing to resonant enhancement but without sacrificing versatility and tunability. We also show that, owing to the large efficiency, cascaded nonlinear effects occur in normal dispersion microresonators once second and third order nonlinearities are combined, expanding the scope and potential of silicon nitride nonlinear photonics.

This conference presentation was prepared for Photonics West 2023.

Dissipative Kerr solitons (DKS) in high-Q microresonators provide femtosecond pulses and frequency combs with high-repetition rate; they have seen applications from optical spectroscopy, data transfer and laser ranging to astronomical spectrograph calibration. Usually DKS are generated in ring-resonators, where only a limited set of design parameters are available. Here, we demonstrate DKS in an integrated high-Q Fabry-Perot microresonator formed by two photonic crystal reflectors in a waveguide. This platform opens a large design space with opportunities for extension of DKS into new wavelength ranges as well as generally phase-matching and spectral engineering for broadband frequency conversion in integrated nonlinear microresonators.

This conference presentation was prepared for Photonics West 2023.

Optical coherence tomography (OCT) is a non-invasive optical technique for high-resolution cross-sectional imaging of specimens, with many applications in clinical medicine and industry (e.g. materials testing, quality assurance, and process control). Current state-of-the-art OCT systems operate in the frequency domain, using either a broadband light source and a spectrometer, known as “spectral-domain OCT” (SD-OCT), or a rapidly tunable laser, known as “swept-source OCT” (SS-OCT). Both systems contain a multitude of fiber and free-space optical components, which make these instruments costly and bulky. The size and cost of an OCT system can be decreased significantly by the use of integrated optics. A suitable fabrication technology and an optimum design may allow one to fabricate very compact, low-cost, and rugged OCT systems. In this talk, I will first introduce the theory of OCT by focusing on SD-OCT systems. System specifications related to design parameters such as axial resolution, imaging depth range, and sensitivity roll-off will be presented. The miniaturization of OCT systems and the pertaining integrated optics components will be discussed, which includes performance-enhanced novel AWG designs as well as ultra-broadband 3dB splitters. Finally, in vivo images taken by the partially-integrated SD-OCT system will be demonstrated.

At PhotonFirst we develop integrated photonics-based sensing solutions for a broad range of applications and markets, with an emphasis on Fiber Bragg Grating (FBG) monitoring applications. The way in which photonic building blocks are combined and connected is vital for the performance, reliability, footprint, manufacturability, and applicability range of the solution. When targeting a broad application base such as sensing, a modular and holistic approach is key. In our contribution we provide examples of PIC-based hybrid integrated solutions specifically developed for sensing applications and use these to highlight the specific sensing requirements and challenges that come with integration.

High Q Fabry-Perot resonators have been achieved using only polymeric materials and lamination process. The resonator is fabricated by two plane parallel Bragg mirrors, commercially available (3M), composed of hundred layers with alternating high- and low-index layers of polyester and acrylic polymer with a high reflectivity (R>98%). The cavity, the mirrors and the substrates are assembled by a cold lamination process. This approach simplifies the fabrication procedure while retaining high optical surface quality, resulting in a compact, low-cost disposable device. Depending on the mirrors reflectivity, FP resonators with quality factor up to Q=180000 and finesse of F=486 have been fabricated.

The mid-IR band recently attracted great interest for future wireless communication due to its low attenuation and high tolerance against atmospheric perturbations. Recent advances in monolithic integration of same-wavelength quantum cascade lasers (QCLs) and detectors (QCDs) paved the way for a new generation of functional photonic integrated circuits. In this context, integrating novel mid-IR plasmonic waveguides has been highly suitable for realizing efficient chip-scale optical links between different active components. Here we report on developing a mid-IR on-chip heterodyne receiver. This includes the first demonstration of plasmonic waveguides for on-chip beam-guiding in the long-wave infrared and novel high-performance QCLs and QCDs.

By using high-throughput computational techniques based on first principles calculations, we characterize the optical and plasmonic properties of transition metal nitrides and carbides, proposed as alternative to standard noble metals for plasmonic applications. In particular, we design a new class of multifunctional metamaterials which combine hyperbolic behavior in the near-IR/visible range with extraordinary mechanical properties, such as extreme hardness, for possible novel applications in harsh environments.

This conference poster presentation was prepared for the Photonics West OPTO 2023 Symposium.

This conference poster presentation was prepared for the Photonics West OPTO 2023 Symposium.

This conference poster presentation was prepared for the Photonics West OPTO 2023 Symposium.

This conference poster presentation was prepared for the Photonics West OPTO 2023 Symposium.

This conference poster presentation was prepared for the Photonics West OPTO 2023 Symposium.

In this paper we present a library of photonic components based on silicon nitride on insulator (SiNOI) waveguide platform. SiNOI is CMOS compatible technology hence it offers mass-scale and low-cost fabrication. It also exhibit much lower propagation losses and thermo-optical coefficient when compared to silicon on insulator (SOI) technology. In addition, it is more tolerant to fabrication tolerance and have wide transparency range from visible to mid-infrared. The SiNOI platform consists of a 400 nm thick SiN layer with 4.5 μm buried silicon dioxide oxide and 3 μm oxide cladding. The library includes single mode waveguides, bend waveguides, power dividers (directional couplers and multimode interferometers), strip to slot mode converters and grating couplers. Components for both the near infrared wavelength at λ=1550 nm and the visible wavelength at λ=633nm are included in this library. These components are the building blocks of various photonic devices and systems for different applications such as light detection and ranging (Lidar) and chemical or biological sensing. The components in the library have been designed and optimized using finite difference eigenmode (FDE) and finite difference time domain (FDTD) solvers. The components of this library were fabricated using applied nanotools (ANT) SiN multi-project wafer (MPW) run. In this MPW run electron beam lithography is used for waveguide patterning. The minimum feature size is 120 nm and the minimum feature spacing is 120 nm. Fully-etched devices are created using anisotropic inductively coupled plasma - reactive ion etching (ICP-RIE) process. The components were experimentally characterized and measurement results were obtained.

This conference poster presentation was prepared for the Photonics West OPTO 2023 Symposium.

This conference poster presentation was prepared for the Photonics West OPTO 2023 Symposium.