Sarat Gundavarapu

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.

Integrated ultra-low-loss silicon nitride waveguide coil for optical gyroscopes

We demonstrate, for the first time, a Sagnac sensor using an on-chip 3m ultra-low-loss silicon nitride waveguide coil.

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.

Programmable eye-opener lattice filter for multi-channel dispersion compensation using an integrated compact low-loss silicon nitride platform

A tunable eye-opening lattice filter for dispersion compensation is demonstrated on an ultra low-loss waveguide platform based on a compact high-aspect ratio Si3N4 core. A programmable 10th order lattice filter is demonstrated by cascading a total of 21 Mach-Zehnder interferometers with programmable delay lines of lengths designed at the baseband data rate. The filter has a footprint of 2.23 cm2 with continuously tunable dispersion from -500 ps/nm to 500 ps/nm. The filter shows a periodic transfer function with a measured FSR of 100 GHz capable of compensating multiple WDM channels with a single device.

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.

Monolithically integrated dual-channel coherent receiver with widely tunable local oscillator for 100 Gbps dual-polarization quadrature phase shift keying applications.

We report implementation of a monolithically integrated 100 Gbps dual-polarization quadrature phase shift keying (DP-QPSK) wavelength tunable coherent receiver on a 1  mm×3  mm die that consists of a tunable C-Band local oscillator with a 40 nm range, eight 30 GHz photodetectors, and two parallel 90° optical hybrids. A BER of 10(-3) with an OSNR of 7.5 dB operating at 50 Gbps NRZ-QPSK data per channel is reported.