A Fabry-Perot interferometer is an instrument commonly used in high resolution optical spectroscopy, and as a tool for the analysis of laser radiation. Etalons are widely used in telecommunications, lasers, and spectroscopy for controlling and measuring the wavelength of light. For example, a laser beam typically comprises several discrete optical frequencies related to different modes of oscillation of the laser resonator. The Fabry-Perot interferometer can be used to determine the number of modes oscillating.
The Fabry-Perot interferometer comprises two parallel mirrors and a Fabry-Perot etalon which has certain optical resonator properties. One of the mirrors is fabricated at different distances (two or more levels) from the other mirror. Conventional spectrometers comprise a large, expensive, and complex system of lenses and mirrors. More recently, attempts have been made to manufacture a Fabry-Perot interferometer within a monolithically integrated circuit. See for example, “Single-chip CMOS optical microspectrometer”, J. H. Correia et al., Sensors and Actuators, 82 (2000) 1.91-197.
These etalon fabrication of fixed cavity filters in monolithically integrated circuits include multiple timed etches for providing varying discrete levels of one mirror. However, establishing the distance of the mirror levels by a timed etch is inaccurate for dimensions involving wavelengths on the order of 400 to 1000 nanometers.
Accordingly, it is desirable to provide a method of fabricating a Fabry-Perot filter in an integrated circuit whose mirror levels may be accurately determined. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.