High-Q optical resonators offer access to nonlinear physics at low pumping powers attainable using non-amplified semiconductor lasers. Recent resonator advances offer Q factors over 200 million in platforms that are fully CMOS compatible. I will review these new systems and how they are making possible a new generation of frequency microcombs.

We report SCG over 1.4 octave(from 620nm to 1.5µm) by pumping at 1060nm on a dispersion-engineered ultra low-loss SiN integrated waveguide with femtosecond pulse of 300W as peak power. We demonstrate SCG over 2.5 octaves(from 580nm to 2.05µm) when a wider and longer waveguide being pumped at 1550nm with peak power of 800W. We also experimentally observe a 4.5 octaves(from 500nm to 2.75µm) SCG by pumping at 1550nm on the 800nm thick SiN platform. We show the versatility of CEA LETI 800nm thick ultra-low loss SiN platform to SCG,

Silicon nitride offers many advantages for integrated nonlinear photonics. Pushed by recent progress in fabrication, we now have access to very low loss waveguides while maintaining large flexibility in terms of dispersion engineering, both essential for the design of efficient nonlinear systems. As such many nonlinear optical demonstrations, mainly based on 3rd order effects in the telecom band, have been performed. In this talk I will cover our recent work on dispersion engineered systems based on the inherent 3rd order effects for efficient and controlled frequency conversion either through four-wave mixing or supercontinuum generation.

This conference presentation was prepared for Photonics West, 2023,

Periodically patterning silicon with a subwavelength pitch opens new degrees of freedom to control the propagation of light and sound in silicon photonic circuits with unprecedented flexibility. In this invited presentation, we will show our most recent results on the use suspended silicon waveguides for supercontinuum generation in the near-IR and mid-IR. We will also discuss our recent demonstrations of subwavelength engineering of photons and phonons in suspended and non-suspended silicon optomechanical cavities

The interaction between light and phonons is strongly enhanced when both optical and mechanical confinement are achieved on micro and nanoscale optical cavities and waveguides. These enhanced interactions enabled many new features such as generating of radio-frequency signals, suppressing stimulated light scattering and probing mesoscopic phonon modes. In this talk, we review our recent progress in the field based upon on dielectric microand nano-cavities and waveguides to enhance or suppress both dispersive and dissipative interaction between light and mechanical waves.

This conference presentation was prepared for Photonics West, 2023,

In this talk, we present progress on scaling the fabrication of thick film silicon nitride photonics integrated circuits to volume and discuss the advantages of low loss photonic integrated circuits. We will present the LIGENTEC offering for low loss silicon nitride PICs for application such as quantum, LiDAR and sensing. Options of active integration, such as LNOI are discussed. The offering includes fast R&D cycles in low volume PIC fabrication though multi-project wafer runs to high volume PIC fabrication in an automotive qualified CMOS line.

Subwavelength metamaterials allow to synthesize tailored optical properties which enabled the demonstration of photonic devices with unprecedented performance and scale of integration. Yet, the development of metamaterial-based devices often involves a large number of interrelated parameters and figures of merit whose manual design can be impractical or lead to suboptimal solutions. In this invited talk, we will discuss the potentiality offered by multi-objective optimization and machine learning for the design of high-performance photonic devices based on metamaterials. We will present both integrated devices for on-chip photonic systems as well as recent advances in the development of devices for free-space applications and optical beam control.

Subwavelength grating (SWG) structures are extremely versatile optical metamaterials that have become a fundamental design tool for the optimization of photonic devices. The importance of SWG structures arises from their capability to synthesize artificial materials with tailorable optical properties, including refractive index, dispersion, or anisotropy. In this invited talk, our advances in SWG topologies to further expand the design space of silicon photonic devices are discussed. The proposed topologies enable enhanced performance such as bandwidth broadening, polarization independency, or increased feature sizes, paving the way for the next generation of SWG-optimized devices.

This conference presentation was prepared for Photonics West, 2023,

Metasurfaces supporting bound states in the continuum (BICs) have emerged as a powerful nanophotonic platform because of their exceptional resonance control and large field enhancements ideal for light-matter coupling. Van der Waals (vdW) materials are particularly interesting for nanophotonics because of their unique optical and electronic properties. This talk will introduce BIC-driven metasurface concepts based on the prominent vdW materials hexagonal boron nitride and the transition metal dichalcogenide WS2, demonstrating broad spectral tunability, ultrasharp resonances, and strong light-matter coupling. Material-intrinsic BIC platforms are broadly applicable for many vdW materials and especially TMDs, delivering both basic insights and practical polaritonic devices.

This presentation discusses new ways of designing nanophotonic devices using deep learning. I will present our efforts in developing generalized artificial neural network (ANN) approaches for evaluating 3D nanostructures in free space and integrated photonic circuits, taking into account complex interactions. New results on highly multi-objective, ANN-driven inverse design of complex scattering matrices in multimode silicon photonic waveguides is presented, which enable ultracompact routers and programmable switches for photonic AI and quantum chips.

This paper discusses the potential of GeSn semiconductors as versatile building blocks for manufacturable silicon-integrated mid-infrared photonic and optoelectronic devices. This wavelength range is highly attractive to implement a variety of applications including heat harvesting, spectroscopy, free-space and fiber-optical communications, surveillance and recognition, remote biochemical sensing, and medical imaging. Challenges related to the wafer-level epitaxial growth of these metastable semiconductors on silicon will be addressed and their atomic-level properties will be discussed. Furthermore, their integration in device processing will also be presented. Examples including lasers, light-emitting diodes, high-speed photodetectors, and thermophotovoltaic cells operating in the mid-infrared range will be described and their performance discussed.

A low noise linear mode avalanche photodiodes (LmAPDs) is a critically enabling component for eye-safe long range LiDAR and remote sensing applications. Unlike PIN diodes, APDs provide internal gain that can lead to increased signal to noise ratio and suppress downstream circuit noise. Commercial APDs use an InGaAs absorber with an InAlAs or InP multipliers. We have recently demonstrate GaAsSb/AlGaAsSb separate absorber charge and multiplier (SACM) heterostructures . We will discuss the technical challenges associated with the design, growth, fabrication and test of these LmAPDs and the potential for the development of these critical APD arrays for active 3D sensing and imaging systems.

Optical phased arrays in silicon photonics are an emerging technology for free-space communications and light detection and ranging (LIDAR). While traditional LIDARs with discrete components and mechanical beam steering are difficult to integrate and scale, silicon-based arrays have taken a massive leap forward in developing beam steering systems with compact footprint and high performance on a single chip. Here, we report our results in the development of chip-scale circular phased arrays. Arrays formed in a grid of concentric rings are shown to suppress the sidelobes, expand the steering range and obtain narrower beamwidths, with large spacing between optical elements.

The demand for optical technologies in space is growing rapidly driven by the advent of low-earth orbit satellite “mega-constellations” providing global communication services. Free space optical communications between satellites in low earth orbit presents a number of technology challenges related to maintaining stable links between two satellites separated by thousands of kilometers. One principal challenge is the development of mechanically robust, mass-producible beam-steering technologies with low SWaP, and recurring cost. One potential solution to this challenge is to replace costly mechanical steering mechanisms with beam-steering elements such as on-chip optical phase arrays. This work presents ongoing research towards the development of an on-chip wide-steering optical phase array for inter-satellite communications. The presentation will cover the system architecture, component design, and control algorithms for synchronizing many emitters into a single output beam.

Measuring polarisation, spectrum, temporal dynamics, and spatial complex amplitude of optical beams is essential to studying phenomena in laser dynamics, telecommunications and nonlinear optics. Here, we harness principles of spatial state tomography to measure a complete description of an unknown beam as a set of spectrally, temporally, and polarisation resolved spatial state density matrices. Each density matrix slice resolves the spatial complex amplitude of multiple mutually incoherent fields, which over several slices reveals the spectral or temporal evolution of these fields even in scenarios when they spectrally or temporally overlap. We demonstrate these features by characterising the rich spatiotemporal and spatiospectral output of a vertical-cavity surface-emitting laser.

This conference presentation was prepared for Photonics West, 2023,

This conference presentation was prepared for Photonics West, 2023,

The success of nanopore sequencers for DNA has inspired extensive research on proteins. However, when moving to proteins some major challenges remain, among them: 1) DNA bases are just 4 against the amino acids which are 20; (2) spatial and temporal resolution (sensitivity) to discriminate single amino acids within the same molecule. In this context, label-free optical analysis based on plasmonic enhancement shows great promises. In fact, plasmonic nanopores can confine and amplifying the local electromagnetic field into the pore (challenge #2). The confinement improves the spatial resolution while the amplification increases the sensitivity. Notably, Raman spectroscopy provides unique molecular fingerprints to discriminate amino acids (challenge #1). We show our latest results on extreme plasmonic nanopores combined with Raman Spectroscopy for amino acids identification and sequencing at single molecule level in label-free. We acknowledge support from Horizon 2020 (ProID GA 964363).

The development of advanced optoelectronic systems requires the intimate integration of multiple, different photonic materials and device structures at micron scales. A number of approaches are being explored to address this pressing challenge. Here we focus on soft-stamp-based transfer printing in both planar and roll based formats, to achieve a widely applicable capability in heterogeneous integration with micron-scale accuracy. We illustrate the capabilities of our custom tools by two examples, the first focusing on planar printing of GaN microlenses onto diamond substrates and waveguide facets and the second focusing on continuous roll-based printing of GaN micro-LED pixels at quarter VGA resolution.

Excitons in atomically thin semiconductors are sensitive to their electronic and photonic environments. Therefore, they exhibit rich exciton dynamics. They are confined in the vertical direction while extending and diffusing along the atomically thin plane. Excitons can also interact with each other, notably to reduce light emission at high densities through exciton-exciton annihilation. Furthermore, their fluorescence is affected by their nanoscopic environment. Here we present our experimental and theoretical results on the fluctuation, diffusion, and annihilation of excitons near nanostructures. Our results have implications for exciton-based sensors, single-photon sources based on 2D materials, and efficient and high-power light-emitting devices.

This conference presentation was prepared for Photonics West, 2023,

Emerging passive optical networks (PONs) standards target 25Gb/s and 50Gb/s systems, requiring high optical powers without amplification. Externally modulated lasers (EMLs) yield low chirp. However, achieving output modulated power exceeding 10 dBm is challenging due to modulator insertion losses and saturation. In this invited presentation we will show our recent results in the development of EMLs based on semi-insulating buried heterostructure (SIBH) waveguide. We will present the main EML design rules and compromises, then apply them to different EMLs aiming at major telecom and datacom applications, with special focus on novel devices addressing the needs of emerging PON applications.

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