Low-κ, narrow linewidth III-V-on-SOI distributed feedback lasers with backside sampled Bragg gratings.

We demonstrate a heterogeneously integrated III-V-on-SOI distributed feedback laser with a low grating strength (κ < 40 cm) and a narrow linewidth of Δν = 118 kHz. The laser operates single mode with a side-mode suppression ratio over 45 dB, provides a single-sided waveguide-coupled output power of 22 mW (13.4 dBm) and has a wall-plug efficiency of 17%.

Athermal silicon photonic wavemeter for broadband and high-accuracy wavelength measurements.

We propose and demonstrate an integrated wavemeter capable of accurate and broadband measurements without control or knowledge of the temperature. In our design, interferometers composed of silicon and silicon nitride waveguides enable accurate measurements of an input optical wavelength despite large and rapid temperature fluctuations of 20°C by leveraging the disparity in thermo-optic properties of the waveguides. We derive formulas which resolve the wavelength and temperature ambiguity of the interferometers.

Handheld free space quantum key distribution with dynamic motion compensation.

Mobile devices have become an inseparable part of our everyday life. They are used to transmit an ever-increasing amount of sensitive health, financial and personal information. This exposes us to the growing scale and sophistication of cyber-attacks.

Timing characterization of 100 GHz passively mode-locked discrete mode laser diodes.

We report on the characterization of the timing stability of passively mode-locked discrete mode diode laser sources. These are edge-emitting devices with a spatially varying refractive index profile for spectral filtering. Two devices with a mode-locking frequency of 100 GHz are characterized.

Design of waveguide-integrated semiconductor laser sources for optical frequency comb generation.

A numerical study of threshold gain and modal dispersion in integrated semiconductor laser optical frequency comb sources is presented. We consider an example device where one of the cleaved facets of the laser is replaced by a short Bragg grating section and show that as many as 16 modes can be selected at the first harmonic of the underlying Fabry-Perot cavity. An intracavity approach to limiting the grating-induced dispersion that can be implemented directly through the grating profile is demonstrated.

Nanoscale optical detector with single-photon and multiphoton sensitivity.

We present the first nanoscale (down to approximately 50 x 50 nm(2)) detector displaying single-photon sensitivity and a nanosecond response. This type of nanodetector can also be operated in multiphoton mode, where the detection threshold can be set at N = 1, 2, 3, or 4 photons, thus allowing the mapping of photon number statistics on the nanoscale. Its operation principle based on that of hot-spot formation in superconducting nanowires allies the temporal resolution and sensitivity of superconducting single-photon detectors with subwavelength resolution and photon number discrimination.

Passive harmonic mode locking by mode selection in Fabry-Perot diode lasers with patterned effective index.

We demonstrate passive harmonic mode locking of a quantum-well laser diode designed to support a discrete comb of Fabry-Perot modes. Spectral filtering of the mode spectrum was achieved using a nonperiodic patterning of the cavity effective index. By selecting six modes spaced at twice the fundamental mode spacing, near-transform-limited pulsed output with 2 ps pulse duration was obtained at a repetition rate of 100 GHz.

Numerical analysis of a high-resolution fast tunable filter based on an intracavity Bragg grating.

A fast tunable filtering technique is proposed associating a diffraction grating with an intracavity Bragg grating. The bandwidth and the tuning range of this filter can be easily adapted by changing the diffraction grating's orientation, or its period, and its response is uniform over the whole tuning range. A numerical simulation of the filter response to a Gaussian beam has been developed, and it fits the experimental results allowing a calculation of the performances that could be obtained with more specific elements.

Uniform response high resolution tunable optical filtering using a grating-assisted acousto-optic device.

A new filtering technique is proposed that associates the high dispersion of standard reflection gratings with the tuning speed of acousto-optic cells. Tuning is performed by adjusting the grating period so that the chosen wavelength is at Bragg resonance. In this way, the selected wavelength always experiences a maximum diffraction efficiency, ensuring good uniformity.