Mode-locked lasers find their use in a large number of applications, for instance, in spectroscopic sensing, distance measurements, and optical communication. To enable widespread use of mode-locked lasers, their on-chip integration is desired. In recent years, there have been multiple demonstrations of monolithic III-V and heterogeneous III-V-on-silicon mode-locked lasers. However, the pulse energy, noise performance, and stability of these mode-locked lasers are limited by the relatively high linear and nonlinear waveguide loss, and the high temperature sensitivity of said platforms. Here, we demonstrate a heterogeneous III-V-on-silicon-nitride (III-V-on-SiN) electrically pumped mode-locked laser. SiN’s low waveguide loss, negligible two-photon absorption at telecom wavelengths, and small thermo-optic coefficient enable low-noise mode-locked lasers with high pulse energies and excellent temperature stability. Our mode-locked laser emits at a wavelength of 1.6 μm, has a pulse repetition rate of 3 GHz, a high on-chip pulse energy of ≈2 pJ, a narrow RF linewidth of 400 Hz, and an optical linewidth <1 MHz. The SiN photonic circuits are fabricated on 200 mm silicon wafers in a CMOS pilot line and include an amorphous silicon waveguide layer for efficient coupling from the SiN to the III-V waveguide. The III-V integration is done by micro-transfer-printing, a technique that enables the transfer of thin-film devices in a massively parallel manner on a wafer scale.

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The gate threshold voltage (Vth) shift under positive gate bias stress is one of the most important reliability concerns in silicon carbide metal–oxide–semiconductor field effect transistors (SiC MOSFETs). Because dynamic recovery is observed as soon as the gate bias stress is removed, it is remarkably difficult to accurately evaluate Vth shifts. Many studies have focused on how to evaluate Vth shifts of SiC MOSFETs under positive gate bias stress. In this study, this issue is investigated by introducing a fast measurement technique. We show that the measured Vth shift is modified to take the Vth recovery term into consideration. Furthermore, we show that the Vth shift is a saturation phenomenon and that the maximum Vth shift can be predicted using an electron capture and emission model.

A sputtered phase-change material, Ge 10 Sb 90 , processed into dots with a height and diameter of 50 nm, shows rapid crystallization triggered by 300 ps laser excitation. Crystallization takes place with a short time delay of approximately 70 ns for a sample with Sb seed layers. The delay becomes just 15-20 ns when a NiCr layer is provided to control the heating-cooling profi le. The nanodot sample requires less energy for crystallization, with a large optical change equivalent to that of the blanket fi lm. These results demonstrate that the nanodot phase-change material could be a possible candidate for next-generation "green" optical storage.Adv. Optical Mater. 2013, 1, 820-826 821 wileyonlinelibrary.com

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