Minh A. Tran

Frequency modulated lasers for interferometric optical gyroscopes.

We study the use of frequency modulated lasers in interferometric optical gyroscopes and show that by exploiting various frequency modulation signals, the laser coherence can be controlled. We show that both angle random walk and bias stability of an interferometric optical gyroscope based on laser sources can be improved with this technique.

A Robust Method for Characterization of Optical Waveguides and Couplers

We propose a simple yet powerful method to characterize waveguide propagation loss and 2 × 2 waveguide couplers coupling coefficient simultaneously. The method, based on the spectrum analysis of transmission through an unbalanced Mach-Zehnder interferometer, requires only a single test structure and is insensitive to variation of input coupling losses. We show that, in most general cases, it is possible to determine both the propagation loss and the coupling of both couplers that can have different coupling coefficients.

Integrated chip-scale Si 3 N 4 wavemeter with narrow free spectral range and high stability

We designed, fabricated, and characterized an integrated chip-scale wavemeter based on an unbalanced Mach-Zehnder interferometer with 300 MHz free spectral range. The wavemeter is realized in the Si3N4 platform, allowing for low loss with ∼62  cm of on-chip delay. We also integrated an optical hybrid to provide phase information. The main benefit of a fully integrated wavemeter, beside its small dimensions, is increased robustness to vibrations and temperature variations and much improved stability over fiber-based solutions.

Integrated Sagnac optical gyroscope sensor using ultra-low loss high aspect ratio silicon nitride waveguide coil

We demonstrate operation of an interferometric optical gyroscope that uses an on-chip 3m ultra-low-loss silicon nitride waveguide coil. The measured minimum waveguide loss of the waveguide coil fabricated using lithographic die stitching was 0.78 dB/m. The angle random walk and bias instability of the gyroscope were characterized to be 8.52 deg/hr1/2 and 58.7 deg/hr respectively.

The first integrated optical driver chip for fiber optic gyroscopes

We have designed and fabricated the first “integrated optical driver” chip for fiber gyroscopes on Si/III–V heterogeneous integration platform. The chip was successfully interrogated with a fiber coil to realize an open-loop IFOG.

Effect of direct PRBS modulation on laser driven fiber optic gyroscope

We demonstrate that direct frequency modulation with a pseudo random bit sequence (PRBS) improves the angle random walk (ARW) and bias instability (BIS) for a laser-driven fiber optical gyroscope over a continuous wave (CW) laser driven gyroscope. The PRBS modulation is shown to improve the ARW to 0.076 deg/hr1/2 and BIS to 2.298 deg/hr compared to an ARW of 0.172 deg/hr1/2 and BIS of 5.862 deg/hr for the CW case.