Thermo-optic phase shifters based on silicon-on-insulator platform: state-of-the-art and a review.

Silicon photonic platforms offer relevance to large markets in many applications, such as optical phased arrays, photonic neural networks, programmable photonic integrated circuits, and quantum computation devices. As one of the basic tuning devices, the thermo-optic phase shifter (TOPS) plays an important role in all these applications. A TOPS with the merits of easy fabrication, low power consumption, small thermal time constant, low insertion loss, small footprint, and low crosstalk, is needed to improve the performance and lower the cost of the above applications.

Silicon ring resonators with a free spectral range robust to fabrication variations.

We propose a design method for silicon ring resonators (RRs) with a free spectral range (FSR) insensitive to fabrication variations. Two waveguide-core widths are used in the RR, with opposite signs of the group-index derivative with respect to the width. This results in cancellation of the width-dependent FSR changes.

Integrated photonics interferometric interrogator for a ring-resonator ultrasound sensor.

We present a compact integrated photonics interrogator for a ring-resonator (RR) ultrasound sensor, the so-called MediGator. The MediGator consists of a special light source and an InP Mach-Zehnder interferometer (MZI) with a 3 ×3 multi-mode interferometer. Miniaturization of the MZI to chip size enables high temperature stability and negligible signal drift.

On-chip silicon Mach-Zehnder interferometer sensor for ultrasound detection.

A highly sensitive ultrasound sensor based on an integrated photonics Mach-Zehnder interferometer (MZI) fabricated in silicon-on-insulator technology is reported. The sensing spiral is located on a membrane of size 121  μm×121  μm. Ultrasound waves excite the membrane's vibrational mode, which translates to modulation of the MZI transmission.

Interrogation of a ring-resonator ultrasound sensor using a fiber Mach-Zehnder interferometer.

We experimentally demonstrate an interrogation procedure of a ring-resonator ultrasound sensor using a fiber Mach-Zehnder interferometer (MZI). The sensor comprises a silicon ring resonator (RR) located on a silicon-oxide membrane, designed to have its lowest vibrational mode in the MHz range, which is the range of intravascular ultrasound (IVUS) imaging. Ultrasound incident on the membrane excites its vibrational mode and as a result induces a modulation of the resonance wavelength of the RR, which is a measure of the amplitude of the ultrasound waves.