Analysis of Z-Cut Quartz Etalon with Weight for Wavelength Locker

This paper presents an analysis of the cavity length modulation of a Z-cut quartz etalon equipped with a weight for Laser Diode (LD) wavelength lockers. The electro-optic effect, piezoelectric effect and photo-elastic effect are considered, and the mechanical movement of the etalon with a weight is analyzed by using a mechanical circuit. Approximate equations that clearly explain the mechanical force, mechanical resonance frequency, and Q factor of the mechanical resonance are obtained. The mechanism for improving the modulation efficiency by placing a weight is clarified. We also compare the analysis with experimental results, and show that most of the experimental values are in accord with the calculated values.