Sarat Gundavarapu

Resume

Hi there! I’m Sarat. Welcome to my webpage. I am a graduate student researcher in OCPI lab headed by Professor Daniel Blumenthal at UCSB. My research interests include silicon nitride photonics, optical sensors, nonlinear optics, narrow linewidth lasers, and biophotonics. You can find my professional profile and my current research projects on this webpage.

EDUCATION

Doctor of Philosophy in Electrical and Computer Engineering University of California Santa Barbara, CA, 93106, U.S.A. Research Focus: Integrated Photonics Advisor: Dr. Daniel Blumenthal	Expected: June 2018
Master of Science in Electrical and Computer Engineering University of California Santa Barbara, CA, 93106, U.S.A.	Awarded: September 2014
Bachelor of Technology in Electronics and Communication Engineering Jawaharlal Nehru Technological University, Hyderabad, India	Awarded: April 2007

RESEARCH PROJECTS

Integrated Waveguide Optical Gyroscope

In this project, we developed a chip-scale Si₃N₄ waveguide coil based gyroscope. We used an analytical noise model to estimate the gyroscope performance achievable with an on-chip waveguide coil. Based on the results, an ultra-low loss Si₃N₄ waveguide coil (0.6 dB/m) was fabricated, packaged, and used as the sensing element in a Sagnac loop to detect rotation rate. We demonstrated a rate grade gyroscope using a 3 m on-chip waveguide coil with a sensitivity of 8.52 °/√hr and bias instability of 58.7 °/hr.

Role: Design of ultra large area, low loss Si₃N₄ waveguide coil; Characterization of gyroscope performance

Expertise gained: Optical sensors, Gyroscopes, Ultra-low loss Si₃N₄ Waveguides, Frequency modulated lasers

Software tools: MATLAB, Fimmwave

Key optical measurements: Optical Backscatter Reflectometry, Allan Deviation Measurements, Rotation rate calibration, Closed loop control

Integrated waveguide Brillouin Laser

In this project, we developed an optically pumped on-chip Si₃N₄ waveguide Brillouin laser. We utilized COMSOL simulations to estimate the Brillouin gain spectrum of lowly confined Si₃N₄ waveguides and designed a low loss, high Q waveguide laser resonator to match the Brillouin gain shift. (Complete results yet to be published. arXiv link provided below)

Role: Simulation/design/characterization of on-chip Brillouin lasers

Expertise gained: Brillouin gain/noise dynamics, Brillouin sensing, Kerr effect and Raman scattering

Software tools: MATLAB, Fimmwave, COMSOL, LUMERICAL

Key optical measurements: Pump probe measurements, Ring down spectroscopy, Sideband spectroscopy, PDH locking, Photonic microwave synthesis, Phase and frequency noise analysis

HONORS

· Best Student Paper Award in honor of “Shaoul Ezekiel” at “The 25th International Conference on Optical Fiber Sensors”, Jeju, South Korea, April 2017

· Doctoral student travel grant, April 2017, Academic senate, UC, Santa Barbara

WORK EXPERIENCE

Optical Chip Test Intern, Packet Photonics, CA

June 2013 – March 2014

Worked on DC/RF characterization of fast tunable, chip scale, InP lasers and modulators. Was responsible for assembly of optical measurement setup and development of automated tests for wafer and die level characterization of devices. Used tools: Python (scripting, Django), VB GUI design/scripting, GPIB interfacing. (Packet Photonics was acquired by Coriant Advanced Technology and OEsolutions in 2015)

Member Technical, Broadridge Financial Solutions, India	October 2007 – September 2011
Worked as a database/UNIX programmer to develop brokerage backend solutions for investment banks such as BOJ, JP Chase Japan, Mizuho securities. My primary duties/responsibilities included SQL programming, UNIX scripting for regression testing and automation. Used tools: PL/SQL, UNIX scripting, PHP

SKILL SUMMARY

· Research Focus: Fiber and Integrated Optical Sensors, Silicon Nitride Photonics, Nonlinear Optics

· Simulation and Analysis tools: MATLAB, Lumerical, COMSOL, IPKISS

· Software Tools: Python, SQL, Core Java, UNIX scripting

PUBLICATIONS

[1]          S. Gundavarapu et al., “Interferometric Optical Gyroscope based on an Integrated Ultra Low Loss Si3N4 Waveguide Coil,” J. Light. Technol., vol. 8724, no. c, pp. 1–1, 2017.

[2]          S. Gundavarapu et al., “Integrated Waveguide Brillouin Laser,” pp. 1–15, 2017.

[3]          S. Gundavarapu et al., “Integrated Sagnac optical gyroscope sensor using ultra-low loss high aspect ratio silicon nitride waveguide coil,” vol. 10323, p. 103231A, 2017.

[4]          S. Gundavarapu, T. Komljenovic, M. A. Tran, M. Belt, J. E. Bowers, and D. J. Blumenthal, “Effect Of Direct PRBS Modulation on Laser Driven Fiber Optic Gyroscope,” vol. 1, pp. 8–10.

[5]          R. Moreira, S. Gundavarapu, and D. J. Blumenthal, “Programmable eye-opener lattice filter for multi-channel dispersion compensation using an integrated compact low-loss silicon nitride platform,” Opt. Express, vol. 24, no. 15, p. 16732, 2016.

[6]          S. Gundavarapu, T. Huffman, R. Moreira, M. Belt, J. E. Bowers, and J. Daniel, “Integrated Ultra-Low-Loss Silicon Nitride Waveguide Coil for Optical Gyroscopes,” Opt. Fiber Commun. Conf. 2016, vol. 1, pp. 4–6, 2016.

[7]          M. A. Tran, S. Gundavarapu, M. Belt, T. Komljenovic, D. J. Blumenthal, and J. E. Bowers, “Frequency Modulated Laser Based Interferometric Optical Gyroscope,” CLEO Appl. Technol., p. JTu5A.140, 2016.

[8]          T. Komljenovic, M. A. Tran, M. Belt, S. Gundavarapu, D. J. Blumenthal, and J. E. Bowers, “Frequency modulated lasers for interferometric optical gyroscopes,” Opt. Lett., vol. 41, no. 8, p. 1773, 2016.

[9]          Shen Y., Tran, M., Srinivasan, S., Hulme, J., Peters, J., Belt, M., Gundavarapu, S., Li, Y., Blumenthal, D., and Bowers, J.E., “Frequency modulated laser optical gyroscope,” in IEEE photonics conference, 2015.

[10]        R. Moreira, S. Gundavarapu, and D. Blumenthal, “Compact Programmable Monolithically Integrated 10-Stage Multi-Channel WDM Dispersion Equalizer on Low-Loss Silicon Nitride Planar Waveguide Platform,” Opt. Fiber Commun. Conf. 2015, pp. 10–12, 2015.

[11]        P. H. J. S. Kahan, S. Gundavarapu, K. I. N. N. Guyen, D. O. M. B. Aney, and D. A. J. B. Lumenthal, “Monolithically integrated dual-channel coherent receiver with widely tunable local oscillator for 100 Gbps dual-polarization quadrature phase shift keying applications,” Opt. Lett., vol. 40, no. 18, pp. 4313–4316, 2015.

PATENTS

Blumenthal, Daniel, Holger Klein, Chad Althouse, Todd Chicci, Patrick Bybee, Henrik Poulsen, and Sarat Chandra Gundavarapu. "Fast calibration and programming optical components." U.S. Patent 9,543,737, issued January 10, 2017.