Two-dimensional integrated optical phased array with high fill-factor antennas.

A silicon photonics optical phased array with a two-dimensional matrix of antennas is experimentally demonstrated in which the unitary antennas are optimized such that light can be emitted over a high fraction of the overall array surface. This design strategy can be used to obtain a low divergence emitted beam containing a significant fraction of the total emitted power, at the expense of a reduced beam steering range. This type of device can be suited to phase front correction in optical wireless communications systems.

Dual-polarization pump rejection filter in silicon nitride technology.

On-chip pump rejection filters are key building blocks in a variety of applications exploiting nonlinear phenomena, including Raman spectroscopy and photon-pair generation. Ultrahigh rejection has been achieved in the silicon technology by non-coherent cascading of modal-engineered Bragg filters. However, this concept cannot be directly applied to silicon nitride waveguides as the comparatively lower index contrast hampers the suppression of residual light propagating in the orthogonal polarization, limiting the achievable rejection.

Wafer-level calibration of large-scale integrated optical phased arrays.

We present the wafer-level characterization of a 256-channel optical phased array operating at 1550 nm, allowing the sequential testing of different OPA circuits without any packaging steps. Using this, we establish that due to random fabrication variations, nominally identical circuits must be individually calibrated. With this constraint in mind, we present methods that significantly reduce the time needed to calibrate each OPA circuit.

Broadband Fourier-transform silicon nitride spectrometer with wide-area multiaperture input.

Integrated microspectrometers implemented in silicon photonic chips have gathered a great interest for diverse applications such as biological analysis, environmental monitoring, and remote sensing. These applications often demand high spectral resolution, broad operational bandwidth, and large optical throughput. Spatial heterodyne Fourier-transform (SHFT) spectrometers have been proposed to overcome the limited optical throughput of dispersive and speckle-based on-chip spectrometers.

Polarization independent and temperature tolerant AWG based on a silicon nitride platform.

A polarization tolerant optical receiver is a key building block for the development of wavelength division multiplexing based high-speed optical data links. However, the design of a polarization independent demultiplexer is not trivial. In this Letter, we report on the realization of a polarization tolerant arrayed waveguide grating (AWG) on a 300-mm silicon nitride (SiN) photonic platform.

Characterization of SiN Integrated Optical Phased Arrays on a Wafer-Scale Test Station.

Optical phased arrays (OPAs) can produce low-divergence laser beams and can be used to control the emission angle electronically without the need for moving mechanical parts. This technology is particularly useful for beam steering applications. Here, we focus on OPAs integrated into SiN photonic circuits for a wavelength in the near infrared.

Dual-polarization silicon nitride Bragg filters with low thermal sensitivity.

Wideband and polarization-independent wavelength filters with low sensitivity to temperature variations have great potential for wavelength division multiplexing applications. However, simultaneously achieving these metrics is challenging for silicon-on-insulator photonics technology. Here, we harness the reduced index contrast and the low thermo-optic coefficient of silicon nitride to demonstrate waveguide Bragg grating filters with wideband apolar rejection and low thermal sensitivity.

Sub-decibel silicon grating couplers based on L-shaped waveguides and engineered subwavelength metamaterials.

The availability of low-loss optical interfaces to couple light between standard optical fibers and high-index-contrast silicon waveguides is essential for the development of chip-integrated nanophotonics. Input and output couplers based on diffraction gratings are attractive coupling solutions. Advanced grating coupler designs, with Bragg or metal mirror underneath, low- and high-index overlays, and multi-level or multi-layer layouts, have proven less useful due to customized or complex fabrication, however.

Thermally stable hybrid cavity laser based on silicon nitride gratings.

In this paper, we show the experimental results of a thermally stable SiN external cavity (SiN EC) laser with high power output and the lowest SiN EC laser threshold to our knowledge. The device consists of a 250 μm sized reflective semiconductor optical amplifier butt-coupled to a passive chip based on a series of SiN Bragg gratings acting as narrow reflectors. A threshold of 12 mA has been achieved, with a typical side-mode suppression ratio of 45 dB and measured power output higher than 3 mW.

L-shaped fiber-chip grating couplers with high directionality and low reflectivity fabricated with deep-UV lithography.

Grating couplers enable position-friendly interfacing of silicon chips by optical fibers. The conventional coupler designs call upon comparatively complex architectures to afford efficient light coupling to sub-micron silicon-on-insulator (SOI) waveguides. Conversely, the blazing effect in double-etched gratings provides high coupling efficiency with reduced fabrication intricacy.

Custom AFM for X-ray beamlines: in situ biological investigations under physiological conditions.

A fast atomic force microscope (AFM) has been developed that can be installed as a sample holder for grazing-incidence X-ray experiments at solid/gas or solid/liquid interfaces. It allows a wide range of possible investigations, including soft and biological samples under physiological conditions (hydrated specimens). The structural information obtained using the X-rays is combined with the data gathered with the AFM (morphology and mechanical properties), providing a unique characterization of the specimen and its dynamics in situ during an experiment.