Numerous applications, e.g., systems for chemical analysis by optical absorption and emission line characterization, will benefit from the availability of low-cost single-chip spectrometers. A single-chip CMOS optical microspectrometer containing an array of 16 Ž. addressable Fabry-Perot etalons each one with different resonance cavity length , photodetectors and circuits for read-out, multiplexing Ž and driving a serial bus interface has been fabricated. The result is a chip that can operate using only four external connections including. V and V covering the visible spectral range of the spectrum with FWHMs 18 nm. Frequency output and serial bus interface allow dd ss easy multi-sensor, multi-chip interfacing using a microcontroller or a personal computer. Power consumption is 1250 mW for a clock frequency of 1 MHz.

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Ž. The design, fabrication and measured characteristics of a bulk-micromachined tunable Fabry-Perot microinterferometer FPMI for the visible spectral range are presented. The FPMI is formed by two parallel 40 nm thick silver mirrors supported by a 300 nm low tensile Ž . stress silicon nitride membrane with a square aperture side length of 2 mm and initial cavity gap of 1.2 mm. One of the mirrors is fixed, the other is under tension on a movable Si frame, which is electrostatically deflected, using several distributed electrodes, to control Ž . cavity spacing and mirror parallelism. Performance achieved is: high flatness of the mirrors lr10 for the visible part of the spectrum , Ž . low control voltages -21 V for 450 nm deflection and simple fabrication. q 1999 Elsevier Science S.A. All rights reserved.

A microspectrometer has been realized based on an array of Fabry-Perot optical thin-film filters. The 16-channel microspectrometer is compatible with IC fabrication methods and operates in the visible spectral range with an interchannel shift of 6 nm. Each of the channels is sensitive in a single peak with full-width-half-maximum (FWHM) of 16 nm. Also a FWHM below 2 nm and finesse of 40 for narrow band operation is demonstrated. The device can easily be tuned during fabrication to cover a different spectral band only by adjusting the etching times without affecting the device layout. Such a device is extremely suitable for applications in microsystems because of its small size, high spectral selectivity, and low cost. Microspectrometers for the UV and IR regions are also feasible using this technique.

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