Production of a coherent pair of light beams with a microwave frequency difference from a single extended-cavity diode laser

Sin Hyuk Yim, Donghyun Cho

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Abstract

We produced a pair of coherent laser beams with a 3-GHz frequency difference by optically phase locking two modes from a single, multimode extended-cavity diode laser. This method is complementary to either a direct modulation or an optical phase locking of two independent lasers. A large differential frequency shift between the two modes of the laser allows efficient phase locking. We developed a simple theory to account for the large differential frequency shift. Allan deviation of the beat frequency when the two modes are phase-locked drops as an inverse of the measurement time and it reaches 10-14 when the time is 1 h. Coherent population trapping spectroscopy of Rb atoms using the phase-locked beams resulted in a spectrum as narrow as that of the case using direct modulation by a stable frequency synthesizer.

Original languageEnglish
Article number023107
JournalReview of Scientific Instruments
Volume81
Issue number2
DOIs
Publication statusPublished - 2010 Mar 16

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ASJC Scopus subject areas

  • Instrumentation

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