A procedure is introduced for increasing the sensitivity of measurements in
integrated ring resonators beyond what has been previously accomplished. This is
demonstrated by a high-frequency, phase sensitive lock to the ring resonators. A
prototyped fiber Fabry-Perot cavity is used for comparison of the method to a similar
cavity. The Pound-Drever-Hall (PDH) method is used as a proven, ultra-sensitive
method with the exploration of a much higher frequency modulation than has been
previously discussed to overcome comparatively low finesse of the ring resonator
cavities. The high frequency facilitates the use of the same modulation signal to
separately probe the phase information of different integrated ring resonators with
quality factors of 8.2 x10^5 and 2.4 x10^5.
The large free spectral range of small cavities and low finesse provides a
challenge to sensing and locking the long-term stability of diode lasers due to small
dynamic range and signal-to-noise ratios. These can be accommodated for by a
calculated increase in modulation frequency using the PDH approach. Further, cavity
design parameters will be shown to have a significant affect on the resolution of the
phase-sensing approach. A distributed feedback laser is locked to a ring resonator to
demonstrate the present sensitivity which can then be discussed in comparison to other
fiber and integrated sensors.
The relationship of the signal-to-noise ratio (S/N) and frequency range to the
cavity error signal will be explored with an algorithm to optimize this relationship. The
free spectral range and the cavity transfer function coefficients provide input parameters
to this relationship to determine the optimum S/N and frequency range of the respective
cavities used for locking and sensing. The purpose is to show how future contributions to the measurements and experiments of micro-cavities, specifically ring resonators, is
well-served by the PDH method with high-frequency modulation.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/85824 |
| Date | 10 October 2008 |
| Creators | Chambers, James Paul |
| Contributors | Madsen, Christi K. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, born digital |
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