Despite a great progress in photonics over the past few decades, we are nowhere near the level of integration and complexity in photonic systems that would be comparable to those of electronic circuits, which prevents use of photonics in many applications. This lag in integration scale is in big part a result of how we traditionally design photonics: by combining building blocks from a limited library of known designs, and by manual tuning a few parameters. Unfortunately, the resulting photonic circuits are very sensitive to errors in manufacturing and to environmental instabilities, bulky, and often inefficient. We show how a departure from this old fashioned approach can lead to optimal photonic designs that are much better than state of the art on many metrics (smaller, more efficient, more robust). This departure is enabled by development of inverse design approach and computer software which designs photonic systems by searching through all possible combinations of realistic parameters and geometries. We also show how this inverse design approach can enable new functionalities for photonics, including compact particle accelerators on chip which are 10 thousand times smaller than traditional accelerators, chip-to-chip on on-chip optical interconnects with error free terabit per second communication rates, and quantum technologies.

A variety of communication and sensing applications require higher levels of photonic integration and higher levels of photonic performance. Recently, many advances have been made at a variety of laboratories around the world in laser, modulator, photodetector and photonic integrated circuit performance. One example is high Q resonators on silicon (Q>200 million) resulting in 60 dB noise reduction in DFB self injection locked lasers with integrated linewidths of a few Hertz. Recent progress in InAs quantum dot lasers epitaxially grown on Si show promise for achieving lower cost and higher performance photonic integrated circuits. The discrete density of states inherent to quantum dot lasers has many benefits: 1) reduced threshold current, 2) higher temperature operation, 3) reduced linewidth enhancement factor resulting in reduced reflection sensitivity and reduced linewidth, and 4) improved reliability. Prospects and results for integration of quantum do

Heterogeneous integration of advanced chalcogenide glass onto the silicon-on-insulator platform allows us to explore novel photonic functions by leveraging the exceptional properties of chalcogenide, as well as the mature complementary metal–oxide–semiconductor (CMOS)-compatible nanophotonic fabrication process. We review our recent progress in heterogeneously integrated chalcogenide-silicon photonic devices such as high-Q resonators, athermal optical waveguides, and Raman-Kerr combs.

For several years, there has been a diversification of applications addressed by silicon photonics. Historically intended for telecom applications, silicon photonic platforms must now address the needs of transceivers for Data Center Interconnect, 5G backhaul / fronthaul but also those of emerging applications such as circuitry for LiDAR or for high performance computing (Artificial Intelligence, Quantum Computing). In order to meet this growing demand and the diversity of needs accompanying all these applications, CEA LETI has developed a new silicon photonics platform based on 300mm SOI wafers. This development is based in part on the experience acquired over more than 15 years on 200mm technology. Switching to 300mm equipment allows access to more advanced and above all, much more stable manufacturing tools, thus making it possible to envisage the production of complex circuits and large-scale integration of photonic components. For the most critical mask levels, the use of an immersion lithography stepper supported by OPC algorithms dedicated to photonics also opens up new perspectives in the possibilities of component design. In this presentation we will describe this new platform by going through its constituent modules and highlighting application versatility. Characterization results of various components fabricated on this platform will also be presented.

Fraunhofer HHI's hybrid integration platform PolyBoard combines polymer passive waveguides with InP and other materials. We present new functionalities integrated in PolyBoard: Isolation: With a microoptical bench integrated into polymer isolators can be built. Quantum and sensing: By integrating nonlinear materials into the microoptical bench, 2nd (775 nm), 3rd (515 nm), and 4th (387 nm) harmonic generation could be observed 3D: First results for a 2x4 phased array have been achieved Flip-chip laser active alignment: We have developed an active alignment process, which also works for flip-chip lasers which are impossible to electrically contact during the alignment process. First automation results show the potential for cost effective volume scaling.

We design a Quantum Dot (QD) embedded in a vertical-cavity photonic nanowire (NW), deterministically integrated on a silicon-on-insulator (SOI) waveguide (WG), as a novel quantum light source in a quantum photonic integrated circuit (QPIC). Using a broadband QD emitter, we perform finite-difference time domain simulations to systematically tune key geometrical parameters and explore the coupling mechanisms of the emission, to the NW and WG modes. We find distinct Fabry-Perot resonances in the Purcell enhanced emission that govern the outcoupled power into the fundamental TE mode of the SOI-WG. With an optimized geometry that places the QD emitter in a finite NW in close proximity to the WG, we obtain peak outcoupling efficiencies for polarized emission as high as eighty percent.

We present here two critical elements for 3D integrated photonics. Based on large area high quality factor photonic crystal cavities, high power single mode surface emitting lasers can be obtained with very narrow linewidths. Additionally, with dispersion control and Dirac band lattice design, fast full 2p phase control is possible in these photonic crystal cavities. The combination and integration of laser and phase control enables 3D integrated photonic functions with high beam and spectral quality lasers, laser beam front control, and beam steering capabilities.

Silicon-on-insulator and silicon nitride (Si3N4) are powerful integration platforms for photonic circuits, offering cost-efficient mass production at high yield. However, both material systems lack important optical properties such as strong electro-optic effects and the ability to efficiently emit light that are indispensable for realizing advanced on-chip systems. These deficiencies can be overcome by combining passive silicon or Si3N4 waveguides with functional organic cladding materials in a hybrid approach. In this talk, we briefly summarize our work on hybrid electro-optic modulators and then focus on low-cost silicon-organic hybrid (SOH) and Si3N4-organic hybrid (SiNOH) lasers. These devices can be efficiently realized by depositing light-emitting cladding materials onto pre-processed waveguide structures. SOH and SiNOH lasers can address both near-infrared and visible wavelengths and may open an attractive path towards low-cost biosensors for point-of-care diagnostics.

A requirement for high-quality hybrid-integration in integrated photonics is high-power single-mode lasers and semiconductor optical amplifiers (SOAs)., which can overcome losses in coupling of photonic components. Moreover, there is a need for high-power operation of these sources at elevated temperatures to reduce the cost, size, weight and power (C-SWAP) of the integrated photonic system. Freedom Photonics is a leading supplier of high-performance photonic components with a suite of high-power DFBs at 1550 nm and 1310 nm. This talk presents Freedom Photonics next generation high-power, high-temperature O-band distributed feedback lasers (DFBs) and SOAs.

We propose a novel optical isolator concept based on spatially asymmetric coupled modes in magneto-plasmonic slot waveguides. Electromagnetic energy follows different paths in forward and backward propagation directions, and isolation is realized thanks to absorbers positioned on one path. We analytically show that the modes asymmetry can be controlled by opto-geometrical parameters, and can be high even by using moderate gyrotropy magneto-optical material, like diluted composite materials. We evaluate numerically the expected isolator performance, and we discuss about the perspectives of this new concept.

Quantum information processing brings new protocols to the field of communications, by ensuring absolute security of information transfer thanks to the laws of quantum physics. Furthermore, in the field of computing, quantum processing offers the perspective of performing massively parallel calculations, orders of magnitude faster than with a classical computer. For these two applications, excellent detectors are required with ultimate performances. Superconducting nanowire single photon detectors (SNSPDs) are the best candidate, as they can reach near-unity detection efficiency. We are developing on-chip waveguide integrated SNSPDs on 200 mm SOI wafers, addressing both the material, architecture design and fabrication process challenges.

Design of novel integrated photonic components often benefits from periodic geometries (either fully periodic or apodized) along the direction of light propagation, offering a wide range of capabilities including mode matching and optical rerouting. Here, we show how existing iterative methods that were originally developed for resonant nanophotonic systems in the frequency domain can be reliably used for calculation of optical Bloch modes in periodic systems in the complex wavevector domain. This method can be used for arbitrary shaped geometries and even when open boundary conditions are applied, therefore heavily impacting the fast-paced design of integrated photonic devices.

In order to produce a powerful, single and low divergence output beam for 3D sensing applications, integrated Optical Phased Arrays (OPA) must have a large number of closely spaced optical antennas. This high density leads to specific constraints in component design compared to devices for optical transceivers. Furthermore, OPA characterization requires significant adaptations compared to traditional photonic wafer level measurement systems. In this presentation, we will focus on some key components used in a large scale OPAs, describing specific challenges and solutions. We will show characterization results of single components as well as active beam-steering with OPA circuits using our modified wafer-scale prober setup.

Nanoscale photonics relates to the ability of patterning matter, particularly semiconductors, to the sub-micron scale in order to realize ultimate miniaturized devices. General scaling considerations imply a drastic decrease of the energy budget required for triggering a fast nonlinear response. These expectations have been confirmed experimentally leading to novel devices such as ultra-fast optical gates, microwave photonic oscillators, optical parametric oscillators. All these devices features microwatt power budget for operation and few micrometers footprint and Gigahertz bandwidth. We will focus on the recently demonstrated Photonic Crystal Optical Parametric Oscillator and its related technology. We'll discuss their suitability for quantum applications, in particular for quantum information. We will also discuss the use of Optomechanical Crystals as high-purity oscillators and related techniques.

We have optimised the design and fabrication of low-loss type-I femtosecond-laser-written waveguides in PPLN that are single-transverse mode at 780 nm and 1560 nm and mode-matched to single-mode fibres. Spontaneous parametric downconversion (SPDC) has been demonstrated at 1560 nm when pumped with a 780 nm DFB laser and has been characterised with measurement of the second-order cross-correlation g(2) using superconducting nanowire detectors. This novel approach to waveguide fabrication in PPLN offers routes to high levels of integration and high generation rates which is important for many quantum-information applications.

The phase error imposed on the optical phased arrays (OPAs) used for the beam scanner of LiDAR is unavoidable due to the minute dimensional fluctuations that occur during the waveguide manufacturing process. In this study, a fast-reacting beamforming algorithm is developed based on the rotating element vector method for compensating the phase error. The proposed algorithm is highly suitable for the OPA devices comprised of polymer waveguides, allowing each phase modulator to be controlled independently. Additionally using the least square approximation, the beamforming time is shortened to 16 seconds for a 32-channel polymer waveguide OPA device.

Since the integrated optic current sensor (IOCS) is made of various optical components as a waveguide, it has advantages of small volume, reduced manufacturing cost, and is advantageous for mass production. In this work, we demonstrate the tolerance of device performance for providing stable sensing operation in long-term sensing experiment.

Optical phased array (OPA) beam scanners consisting of polymer waveguides have demonstrated precise beam steering with low driving power by taking advantage of the large TO coefficient of the polymer material. However, the slow response time of thermo-optic phase modulators limits the beam scanning time, and it has to be improved for the practical LiDAR application. In this study, a polyimide with a high refractive index is adopted to produce a waveguide with a small waveguide core size to reduce the response time of the thermo-optic phase modulator and improve the beam scanning speed of the OPA device.

We report on the pulse compression performance using FastLas module for different industrial ultra-short pulse lasers. The compression module enables compression down to pulse-duration below 50 fs in most of the representative ultra-short pulse lasers with pulse-duration in the range of 700-250 fs and average power in the range of 10-100W. The overall optical transmission of the module ranges between 70% and 90%, and the output beam quality corresponds M2 of less than 1.2.