High-speed deformation of soft lithographic nanograting patterns for ultrasensitive optical spectroscopy

We demonstrate a spectroscopy technique that implements a high-speed tunable grating to take spectroscopy measurements with a single, extremely sensitive photodetector. The tunable grating consists of a transparent elastomer microbridge soft lithographically patterned and assembled onto silicon microactuators. We show the ability to track the optical spectrum of time-varying multiwavelength signals with a 500μs time resolution and sensitivity capable of detecting optical powers near 36pW. Such a level of sensitivity is suitable for detecting the spectral fluorescence of low concentration dyes, microbeads, or quantum dots.