David J. Moss

All-optical wavelength conversion in an integrated ring resonator

We present the first system penalty measurements for all-optical wavelength conversion in an integrated ring resonator. We achieve wavelength conversion over a range of 27.7nm in the C-band at 2.5 Gb/s by exploiting four wave mixing in a CMOS compatible, high index glass ring resonator at ~22 dBm average pump power, obtaining < 0.3 dB system penalty.We present the first system penalty measurements for all-optical wavelength conversion via four wave mixing in an integrated, CMOS compatible, ring resonator, obtaining < 0.3 dB system penalty at 2.5Gb/s for ∼22dBm average pump power.

Two-photon photodetector in a multiquantum well GaAs laser structure at 1.55μm

We report two-photon photocurrent in a GaAs/AlGaAs multiple quantum well laser at 1.55 microm. Using 1ps pulses, a purely quadratic photocurrent is observed. We measure the device efficiency, sensitivity, as well as the two-photon absorption coefficient. The results show that the device has potential for signal processing, autocorrelation and possibly two-photon source applications at sub-Watt power levels.

A Radio Frequency Channelizer based on Cascaded Integrated Micro-ring Resonator Optical Comb Sources and Filters

We report a broadband RF channelizer based on an integrated optical frequency Kerr micro-comb source, with an RF channelizing bandwidth of 90 GHz, a high RF spectral slice resolution of 1.04 GHz, and experimentally verify the RF performance up to 19 GHz. This approach to realizing RF channelizers offers reduced complexity, size, and potential cost for a wide range of applications to microwave signal detection.

High-order Radio Frequency Differentiation via Photonic Signal Processing with an Integrated Micro-resonator Kerr Optical Frequency Comb Source

We demonstrate the use of integrated micro-resonator based optical frequency comb sources as the basis for transversal filtering functions for microwave and radio frequency photonic filtering and advanced functions. Keywords—frequency comb, microwave, micro-resonator

Integrated Kerr comb-based reconfigurable transversal differentiator for microwave photonic signal processing

An arbitrary-order intensity differentiator for high-order microwave signal differentiation is proposed and experimentally demonstrated on a versatile transversal microwave photonic signal processing platform based on integrated Kerr combs. With a CMOS-compatible nonlinear micro-ring resonator, high quality Kerr combs with broad bandwidth and large frequency spacings are generated, enabling a larger number of taps and an increased Nyquist zone. By programming and shaping individual comb lines’ power, calculated tap weights are realized, thus achieving a versatile microwave photonic signal processing platform. Arbitrary-order intensity differentiation is demonstrated on the platform. The RF responses are experimentally characterized, and systems demonstrations for Gaussian input signals are also performed.

Optical square waves from a nonlinear amplifying loop mirror laser (Conference Presentation)

Optical square wave sources are particularly important for applications inxa0high speedxa0signal processing and optical communications. In most realizations, optical square waves are generated by electro-optic modulation,xa0dispersion engineering of mode-locked lasers,xa0polarizationxa0switching, or by exploiting opticalxa0bi-stabilityxa0and/or optical delayed feedback in semiconductor diode lasers, as well asxa0vertical-cavityxa0surface-emitting lasers (VCSELs). All such configurations are bulky andxa0cause significant timing jitters.xa0Here we demonstratexa0the direct generation of optical square waves from a polarization-maintaining figure-eight nonlinear amplifying loop mirror (NALM) configuration that uses an embedded high index glass micro-cavity as the nonlinear element.xa0Suchxa0a NALMxa0mimics the behavior of a saturable absorber and has been used to reach passivexa0mode-lockingxa0of pico- and even nano-second pulses.xa0In our method, the NALM, including a high-Qxa0micro-ringxa0resonator,xa0acts as an ultra-narrowband spectral filter and at the same time provides a large nonlinear phase-shift. Previously we have demonstratedxa0that such a configuration enables sufficient nonlinear phase-shifts for low-power narrow-bandwidth (~100 MHz FWHM) passive mode-locked laser operation.xa0Here we demonstrate the switching of stable optical square wave pulses from conventional mode-locked pulses by adjusting thexa0cavity properties.xa0In addition, the square wave signal characteristics, such as repetition rate andxa0pulse duration, can be also modified in a similar fashion. The source typically produces nanosecond optical square wave pulses with a repetition ratexa0of ~ 120 MHz atxa01550nm. In order to verify the reach of our approach, we compare our experimental results with numerical simulations using a delay differential equation model tailored for a figure-eight laser.

Graphene bolometer for vis-IR spectral range made on nano-SiN membrane

A sensitive bolometric detector for visible and infrared wavelengths based on a novel assembly principle of a graphene monolayer on a nano/micro SiN membrane is realised. The basic operating principle of the optical detector relies on the absorption of electromagnetic radiation in the graphene and creation of a strong thermal gradient, rT, which is detected via the Seebeck effect: Voltage = S x ∇rT, where S is the Seebeck coefficient of graphene. A simple lithography-free deposition of two metal contacts with different electron work functions: Pd (by sputtering) and Ag (by jet printing and annealing) was used. Sensitivity of the bolometer was the same ~1:1 mV/mW at 1030 and 515 nm wavelengths.

Four-Photon Entanglement Generation with Integrated Optical Frequency Combs

We demonstrate the generation of four-photon entangled quantum states with integrated optical frequency comb sources. We measure four-photon quantum interference with a visibility above 89%, and perform quantum state tomography revealing a fidelity above 64%.

Efficient Wavelength Conversion and Net Parametric Gain via Fwm in a High Index Doped Silica Waveguide

We demonstrate C-band subpicosecond wavelength conversion over > 100nm, exploiting four wave mixing in a high index doped silica waveguide spiral of 45cm, showing a +16.5dB net gain for a 40W peak pump power.