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Browse Prior Art Database

Laser Frequency Divider and Stabilizer

IP.com Disclosure Number: IPCOM000044451D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Brewer, RG: AUTHOR [+2]

Abstract

A sensitive optical interferometric technique dual-frequency modulation (DFM) has been developed for measuring and stabilizing a laser frequency by comparison, in a single step, to a radio frequency (RF) standard. Preliminary measurements give a resolution of 2 parts in 1010, but optimized devices should have a resolution between 10-12 and 10-15 . The principle of the technique rests on phase-locking the mode spacing c/2L of an optical cavity to an RF standard and simultaneously phase-locking a laser to the nth order of the same cavity. When these two conditions are satisfied, the optical frequency 10 and the radio frequency 11 are simply related as 10=n11 . The DFM technique uses two phase modulators driven at frequencies 11 and 12, respectively.

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Laser Frequency Divider and Stabilizer

A sensitive optical interferometric technique dual-frequency modulation (DFM) has been developed for measuring and stabilizing a laser frequency by comparison, in a single step, to a radio frequency (RF) standard. Preliminary measurements give a resolution of 2 parts in 1010, but optimized devices should have a resolution between 10-12 and 10-15 . The principle of the technique rests on phase-locking the mode spacing c/2L of an optical cavity to an RF standard and simultaneously phase-locking a laser to the nth order of the same cavity. When these two conditions are satisfied, the optical frequency 10 and the radio frequency 11 are simply related as 10=n11 . The DFM technique uses two phase modulators driven at frequencies 11 and 12, respectively. Dual- frequency modulation creates, in lowest order, sidebands at 10Å11, 10Å12, and 10Å11Å12
. A photodetector views the cavity in reflection and two error signals are derived, one at 12 and the other at the intermodulation frequency 11Å12 . The first signal at 12 allows locking the laser to the reference cavity and is independent of 11 tuning. The second signal at 11Å12 allows locking the cavity to the RF reference. This signal varies directly with the RF detuning w=11-s and provides the desired null at the RF resonance condition 11=s, while being independent of laser detuning W.

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