Novel Microspectrometer Attains High Resolution with Wide Bandwidth

The microspectrometer is realized by using silicon process compatible fabrication and has a great potential as a high-resolution, large dynamic range, lightweight, compact, high-speed, and versatile microspectrometer.

The spectrometer was designed by engineers at Georgia Institute of Technology, (Atlanta GA, USA). The 81-channel on-chip device achieved 0.6 nm resolution over a spectral range of more than 50 nm with a footprint less than 1 mm². The spectrometer employs a filter array of microdonut resonators, which is coupled to an input bus waveguide. The microdonut resonators are carefully designed such that each of the resonators only taps a small portion of the incoming spectrum that overlaps with its resonance lineshape. The single-mode operation of the microdonut resonators with an outer radius of ~2 μm enables the large free spectral range (FSR) of ~60 nm. The experimental resolution extracted from the calibrated spectral response is ~0.6 nm.

Spectrometers have conventionally been expensive and bulky bench-top instruments used to detect and identify the molecules inside a sample by shining light on it and measuring different wavelengths of the emitted or absorbed light. Previous efforts toward miniaturizing spectrometers have reduced their size and cost, but these reductions have typically resulted in lower-resolution instruments.

Ali Adibi, PhD a professor in the School of Electrical and Computer Engineering at Georgia Institute of Technology, said, "We were able to achieve high resolution and wide bandwidth with a compact single-mode on-chip spectrometer through the use of an array of microdonut resonators, each with an outer radius of two microns." The microspectrometer architecture article was published on June 20, 2011, in the journal Optics Express.

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Georgia Institute of Technology