Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

A compact, thermal noise limited reference cavity for ultra-low noise microwave generation



Josue Davila-Rodriguez, Frederick N. Baynes, Andrew D. Ludlow, Tara M. Fortier, Holly F. Leopardi, Scott A. Diddams, Franklyn J. Quinlan


A 25 mm long, rigidly-held, ultra-stable optical frequency reference cavity is demonstrated. The cavity spacer has an easy-to-manufacture cylindrical shape which nonetheless exhibits a holding geometry predicted to be first-order insensitive to the squeezing force. To decrease the thermal noise limit for such a short cavity the optical beam diameter has been enlarged by increasing the radius of curvature of the curved mirror to 10.2 m. With this configuration, a laser locked to the cavity is predicted to have a thermal noise limited phase noise of -9 dBrad2/Hz at 1 Hz offset from the 280 THz optical carrier, which, after optical frequency division, supports microwave generation at 10 GHz with phase noise near -100 dBc/Hz at 1 Hz offset. Laser phase noise that is nearly thermal noise limited for 3 frequency decades (1 Hz to 1 kHz offset), and supports 10 GHz generation with phase noise 600 Hz, is demonstrated.
Optics Letters


Cavity Stabilized Lasers, Reference Cavities


Davila-Rodriguez, J. , Baynes, F. , Ludlow, A. , Fortier, T. , Leopardi, H. , Diddams, S. and Quinlan, F. (2017), A compact, thermal noise limited reference cavity for ultra-low noise microwave generation, Optics Letters (Accessed February 21, 2024)
Created March 23, 2017, Updated July 3, 2017