In order to observe laser phase noise, this noise must be converted to
amplitude noise, which can be achieved using either an interferometer or an
absorption resonance in an atomic/molecular vapor or gas. When phase noise is
converted to amplitude noise, it is manifested as a heterodyne signal in the
output of an optical square-law detector. Thus, phase noise is measured by
optical heterodyne spectroscopy, or, equivalently, laser phase noise
spectroscopy.
In recent work on diode laser noise spectroscopy of rubidium and oxygen, the
observed spectroscopic lineshapes were not in total agreement with theoretical
predictions. We have repeated the previous work on the oxygen A-band
transitions, and we now find qualitative agreement with theory.
In addition, we have measured the diode laser noise spectrum of a Lummer-
Gehrcke interferometer (LGI), comparing the heterodyne lineshape of a LGI
transmission spectrum with a qualitative theory that we develop in this thesis.
A theory, from other workers, predicts the intensity fluctuations from a
Doppler-broadened, two-level atomic/molecular system driven with a phase-diffusing
laser field. We show that a simplified version of this theory, which
ignores Doppler effects of the system, is a useful approximation to the complete
theory, by comparing computer-generated heterodyne lineshapes of each, for a
rubidium transition. We apply this approximate theory to an oxygen A-band
transition, and compare these results with our experimental measurements.
For the experimental arrangement used in the present work, diode laser noise
spectroscopy may also include effects of selective reflection, which is dealt with
experimentally and theoretically.
Diode laser phase noise has practical importance in optical communications
and atomic clocks. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33207 |
| Date | 16 June 1998 |
| Creators | Wichner, Brian D. |
| Contributors | Fairchild, Cliff E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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