Scalable On‐Chip Microdisk Resonator Spectrometer

Abstract

On‐chip micro‐spectrometers are sought after with great effort owing to extensive potential applications in mobile optical sensing and imaging. By multiplexing more physical channels, the reconstructive spectrometers based on the spectral‐to‐spatial mapping technique can improve the spectral range. However, this method is challenging to implement and sustain due to the increase in system complexity and the decrease of dynamic range or spectral resolution. Here, a micro‐spectrometer utilizing a single tunable microdisk resonator (MDR) is demonstrated. Such a single MDR spectrometer has only one physical channel to receive all spectral components with a compact size, overcoming the trade‐off among spectral resolution, spectral range, and dynamic range. Leveraging the wavelength and temperature‐dependent response matrix, unknown spectra are reconstructed from their corresponding output light intensity vector. The fabricated device illustrates a high resolution of 0.01 nm for a dual peak and a medium resolution of 0.2 nm in the 20 nm spectral range. A wide variety of complex input spectra, including narrowband and broadband spectral signals, can be well recovered, exhibiting the robustness of the spectral reconstruction approach. Moreover, this proposed spectrometer exhibits ease of scalability and flexible configuration to a spectrometer array covering a set of desired and even discrete spectral ranges.

Ultra-compact monolithically-integrated silicon single-microring spectrometer breaking the free-spectral-range limitation

“…More recently, the reconstructive spectrometer paradigm has emerged and received great attention 5,[19][20][21][22][23][24][25][26][27][28][29][30] , in which case diverse spectral signals can be retrieved computationally by pre-calibrating information encoded with orthogonal spectral responses. For reconstructive spectrometers, the performance depends on the diversity of calibration spectrum, and thus more accurate spectrum reconstruction is enabled when more spectrum channels are available 22,24 .…”