State-of-the-Art in Integrated Optical Microspectrometers

Microspectrometers fabricated in silicon using microelectromechanical systems technologies are versatile microinstruments: small, lightweight, and featuring a demonstrated capability for spectral analysis. When realized using silicon process compatible technologies, low-cost batch fabrication of an intelligent optoelectronic system-on-a-chip is feasible by cointegration of optics with microelectronic circuits. However, the spectral resolution of devices presented so far has been limited to about R=15, which does restrict application. This paper provides an overview of microspectrometers operating in the visible and infrared spectral range. Moreover, it is demonstrated that the resolution is primarily limited due to the short optical path that is inherent to a microsystem, optical properties of silicon IC-process compatible materials, and lack of adequate optical signal conditioning.