Compact thermo-optic MZI switch in silicon-on-insulator using direct carrier injection.

In this paper we present a compact direct current injection thermo-optic switch based on a Mach-Zehnder Interferometer configuration that is suitable for autonomous vehicle applications as it has a low heating resistance value of 97 Ω, a rapid 2.16 µs switching time constant, and a Pπ of 28 mW. The device relies on multimode interference to achieve low optical insertion losses of less than 1.1 dB per device, while allowing direct current injection to heat the waveguide and achieve fast operation speeds. Furthermore, the total resistive value can be tailored as the heating elements are placed in parallel.

Silicon optical filter with transmission peaks in wide stopband obtained by anti-symmetric photonic crystal with defect in multimode waveguides.

We experimentally demonstrate and characterize a wide optical stopband filter with transmission peaks constituted by two parallel rows of an anti-symmetric one-dimensional (1D) photonic crystal with defect in a multimode waveguide. The working principle is based on mode coupling for the wavelengths that meet the phase matching condition as the fundamental mode is coupled to a higher-order mode and then filtered out with linear tapers as they are reflected back. The defect in the photonic crystal works as a Fabry-Perot like cavity that allows for localized states in the stopband to quantify the effects of the design parameters and we show a Fabry-Perot filter that extends through the 200 nm stopband. A compact 7 µm2 device is demonstrated with standard fabrication techniques in Silicon-on-Insulator (SOI), and compared to Fabry-Perot filters in single mode waveguides, we obtain a larger bandwidth and lower back reflections. Applications include refractive index sensors, optical communications and on-chip spectroscopy.