Dec 14 (Thu) @ 10:00am: "Low Loss Visible and Near-IR Wavelengths Silicon Nitride Integrated Photonics and Precision Lasers for Atomic and Quantum Systems," Nitesh Chauhan, ECE PhD Defense

Date and Time

Location: Henley Hall, 1010
Zoom Meeting – Meeting ID: 86302880917 | Passcode: di8vVGNvTGlYRHgvUEVmcFFNa242QT09


Visible and near IR stable lasers, stabilization cavities and beam manipulation optics are integral part of atomic, ion and quantum systems. These systems require low frequency noise at the wavelengths of the atomic, molecular or ion transition dictated by the applications for the trapping, preparation, and manipulation of the states. These stable sources today are provided by tabletop lasers locked to bulk stabilization cavities. Moreover, bulk free space optics is used to provide and manipulate the necessary beams to these systems. The miniaturizations and development of portable systems will benefit from integrated optics for reducing the SWaP as well as providing new low frequency noise direct drive sources at the required transition wavelengths of atoms, ions, and molecules enabling new physics.

This research demonstrates the lowest waveguide losses achieved in a CMOS compatible waveguide platform at visible with losses of 2 dB/m at λ=493 nm, 0.6 dB/m at λ=674-698 nm and 0.35 dB/m at λ=780 nm with highest Q g=factors at 20 million at 493 nm, 90 million at 674 and 698nm and 145 million at 780nm. This waveguide is used to provide stable sources for 87Rb two photon clock, 88Sr+ clock and qubit transition, at 698 nm for 87Sr clock transition. These include SBS lasers with low thresholds and a factor of 400-500x reduction in fundamental linewidth and an order of magnitude reduction in integral linewidth. Also, low TRN floor coil resonator stabilization cavities (coilR) at visible are demonstrated, with 3 m length are demonstrated 2-4 orders of magnitude reduction in frequency noise at 674 nm. Another demonstration is the largest waveguide emitted beams from waveguide platform, with beam size of 2.5 mm x 3.5 mm, flat top beams which represent a 20 million times increase in area over a waveguide mode. Three 780 nm beams at 54.7o from chip normal placed at 120o from each other provide three orthogonally intersecting beams to form a MOT at 1 cm above the chip surface for Rb MOT.


Nitesh Chauhan is a 6th year PhD student in Professor Daniel J. Blumenthal's Optical communication and Photonic integration group at University of California, Santa Barbara. His research focuses on low loss integrated photonic circuits for atomic, molecular and ion applications. He received his B.Tech. degree in Electrical Engineering from Indian Institute of Technology, Indore in 2016 and M.S. in Electrical and Computer Engineering from University of California, Santa Barbara in 2018.

Hosted by: Professor Daniel J. Blumenthal

Submitted by: Nitesh Chauhan <>