75-year-old man • recent history of hand-foot-mouth disease • discolored fingernails and toenails lifting from the proximal end • Dx?

► recent history of hand-foot-mouth disease ► discolored fingernails and toenails lifting from the proximal end.

Ultrahigh-Q AlGaAs-on-insulator microresonators for integrated nonlinear photonics.

Aluminum gallium arsenide (AlGaAs) and related III-V semiconductors have excellent optoelectronic properties. They also possess strong material nonlinearity as well as high refractive indices. In view of these properties, AlGaAs is a promising candidate for integrated photonics, including both linear and nonlinear devices, passive and active devices, and associated applications.

High resolution, high channel count mid-infrared arrayed waveguide gratings in silicon.

Arrayed waveguide gratings (AWGs) working in the 4.7 µm wavelength range are reported on silicon-on-insulator waveguides with 1500 nm thick silicon and 2 µm thick buried oxide layers. For eight channel devices, three different channel spacings (200 GHz, 100 GHz, and 50 GHz) with cross talk levels of -32.

Ultra-efficient frequency comb generation in AlGaAs-on-insulator microresonators.

Recent advances in nonlinear optics have revolutionized integrated photonics, providing on-chip solutions to a wide range of new applications. Currently, state of the art integrated nonlinear photonic devices are mainly based on dielectric material platforms, such as SiN and SiO. While semiconductor materials feature much higher nonlinear coefficients and convenience in active integration, they have suffered from high waveguide losses that prevent the realization of efficient nonlinear processes on-chip.

Improved second harmonic performance in periodically poled LNOI waveguides through engineering of lateral leakage.

In this contribution, we investigate the impact of lateral leakage for linear and nonlinear optical waveguides in lithium niobate on an insulator (LNOI). Silicon nitride (SiN) loaded and direct patterned lithium niobate cross-sections are investigated. We show that lateral leakage can take place for the TE mode in LNOI ridge waveguides (X-cut lithium niobate), due to the birefringence of the material.

Low loss (Al)GaAs on an insulator waveguide platform.

In this Letter, we demonstrate a low loss gallium arsenide and aluminum gallium arsenide on an insulator platform by heterogenous integration. The resonators on this platform exhibit record high quality factors up to 1.5×10, corresponding to a propagation loss ∼0.

On-wafer probing-kit for RF characterization of silicon photonic integrated transceivers.

A wafer-level and high-efficiency radio frequency (RF) testing of a photonic device is highly desired in the fabrication and characterization of large-scale photonic integration circuits. In this work, we propose on-wafer probing kit designs, and demonstrate a damage-free, self-calibrated RF characterization of an integrated silicon photonic transceiver with a heterodyne mixing approach. Reduced or even free of fiber coupling off chip operation can be achieved with the on-wafer probing-kit to extract the frequency responses of broadband modulators and photodetectors in the photonic integration transceiver, with no requirement of electro-optical or opto-electrical calibration.

Heterogeneous integration of lithium niobate and silicon nitride waveguides for wafer-scale photonic integrated circuits on silicon.

An ideal photonic integrated circuit for nonlinear photonic applications requires high optical nonlinearities and low loss. This work demonstrates a heterogeneous platform by bonding lithium niobate (LN) thin films onto a silicon nitride (SiN) waveguide layer on silicon. It not only provides large second- and third-order nonlinear coefficients, but also shows low propagation loss in both the SiN and the LN-SiN waveguides.

Electrically pumped continuous-wave 1.3 μm quantum-dot lasers epitaxially grown on on-axis (001) GaP/Si.

We demonstrate the first electrically pumped continuous-wave (CW) III-V semiconductor lasers epitaxially grown on on-axis (001) silicon substrates without offcut or germanium layers, using InAs/GaAs quantum dots as the active region and an intermediate GaP buffer between the silicon and device layers. Broad-area lasers with uncoated facets achieve room-temperature lasing with threshold current densities around 860  A/cm and 110 mW of single-facet output power for the same device. Ridge lasers designed for low threshold operations show maximum lasing temperatures up to 90°C and thresholds down to 30 mA.

Highly linear heterogeneous-integrated Mach-Zehnder interferometer modulators on Si.

In this paper we demonstrate highly linear Mach-Zehnder interferometer modulators utilizing heterogeneous integration on a Si substrate (HS-MZM). A record high dynamic range was achieved for silicon devices, obtained using hybrid III-V/Si phase modulation sections and single drive push-pull operation, demonstrating a spurious free dynamic range (SFDR) of 112 dB∙Hz at 10 GHz, comparable to commercial Lithium Niobate MZMs.

Heterogeneously integrated 2.0 μm CW hybrid silicon lasers at room temperature.

Here we experimentally demonstrate room temperature, continuous-wave (CW), 2.0 μm wavelength lasers heterogeneously integrated on silicon. Molecular wafer bonding of InP to Si is employed.

InP-based waveguide photodiodes heterogeneously integrated on silicon-on-insulator for photonic microwave generation.

High-linearity modified uni-traveling carrier photodiodes on silicon-on-insulator with low AM-to-PM conversion factor are demonstrated. The devices deliver more than 2.5 dBm RF output power up to 40 GHz and have an output third order intercept point of 30 dBm at 20 GHz.

Design of phase-shifted hybrid silicon distributed feedback lasers.

We present data on the design and performance analysis of phase shifted distributed feedback (DFB) lasers on the hybrid silicon platform. The lasing wavelength for various input currents and temperatures, for devices with standard quarter-wavelength, 60 μm and 120 μm-long phase shift are compared for mode stability and output power. The pros and cons of including a large phase shift region in the grating design are analyzed.