OSE Seminar by Dr. Darwin K. Serkland on Narrow-linewidth VCSELs for atomic clocks

Departmental News

Dr. Darwin K. Serkland

Posted: October 4, 2022

Date: Thursday, October 06, 2022

Time:  12:15 PM - 1:15 PM

Location:  CHTM, Room 103 and via Zoom


Vertical-cavity surface-emitting lasers (VCSELs) developed at Sandia played a key role in demonstrating some of the first chip-scale atomic clocks (CSACs), which reduced power consumption of atomic clocks by 99% and opened the door to battery-powered applications. The spectroscopic technique called coherent population trapping (CPT) enables optical rather than microwave interrogation of the ground-state hyperfine splitting of cesium (or rubidium), which defines the fundamental unit of time, the second. Optical interrogation allows the volume and power consumption of an atomic clock to be reduced by orders of magnitude, and vertical-cavity surface-emitting lasers (VCSELs) are preferred optical sources for their low power consumption and single longitudinal mode operation. In 2019 our team reduced VCSEL linewidths from roughly 20 MHz to 2 MHz, using a novel three-mirror VCSEL cavity. This talk will describe atomic clocks, the role of VCSELs, our new narrow-linewidth VCSELs and how they have further improved the performance of atomic clocks.


Darwin Serkland received a B.A. degree in Physics and Mathematics from Carleton College and a Ph.D. degree in Applied Physics from Stanford University. His graduate research was on the generation of squeezed states of light using periodically poled lithium niobate waveguides. He worked at Northwestern University as a post-doctoral fellow and then research professor, studying nonlinear fiber-optic devices using picosecond optical pulses. He is a Distinguished Member of Technical Staff at Sandia National Laboratories, where he leads a team working on research and development of compound-semiconductor optoelectronic devices, including vertical-cavity surface-emitting lasers (VCSELs). He developed narrow-linewidth single-frequency VCSELs for the chip-scale atomic clock (CSAC), which is now a commercial product. He has co-authored over 100 publications. Email: DKSERKL@sandia.gov