Multispectral pixel performance using a one-dimensional photonic crystal design

Abstract

A photodetector pixel using a photonic crystal structure incorporating photoconductive layers has been realized. The fabricated device exploits mode discrimination and resonant cavity enhancement to provide simultaneous multispectral detection capability, high quantum efficiency, and dramatically suppressed shot noise. Detectivities as high as 2.6ϫ 10 10 and 2.0 ϫ 10 10 cm Hz 1/2 W −1 at the two preselected wavelengths, 632 and 728 nm, were achieved, respectively.

Cavity-enhanced Multispectral Photodetector on a Si Platform: Theory, Materials, and Devices

“…Comparing to previous work on multispectral detection using single cavity structures [5], spectral cross talk is suppressed in our design by two orders of magnitude, taking advantage of wavelengthselective spatial localization of resonant modes in different cavities. Electrical signal originating from each wavelength may then be separately read out simply by contacting the corresponding active layer, either in a photoconductive [5] or in a photovoltaic mode. Further, since resonant cavity enhancement (RCE) effect leads to optical field build-up in the cavity and dramatically increases absorption, IR-active layers with reduced thickness can be used and thereby reduce detector noise, while maintaining near unity quantum efficiency.…”

“…Using a transfer matrix formalism, we rigorously prove that critical coupling and near unity quantum efficiency can be achieved for all cavities [4]. Comparing to previous work on multispectral detection using single cavity structures [5], spectral cross talk is suppressed in our design by two orders of magnitude, taking advantage of wavelengthselective spatial localization of resonant modes in different cavities. Electrical signal originating from each wavelength may then be separately read out simply by contacting the corresponding active layer, either in a photoconductive [5] or in a photovoltaic mode.…”

“…Figure 1(c) and 1(d) plot the light intensity distributions in the stack at the two designed resonant wavelengths. Our design leads to spectral cross talk as low as 0.1%, which is more than two orders of magnitude lower compared to a tandem design [8] or a single cavity design [5]. Polycrystalline PbTe films are chosen as the IR-active material to facilitate monolithic integration with Si ROIC.…”

Review of snapshot spectral imaging technologies

“…134 The cavity-enhanced multispectral photodetector is designed by sandwiching several thin layers of amorphous silicon (used as the detection layers) in a resonance-enhanced cavity. 135 Sun et al 131 and Wang et al 136 report on using this approach to measure two narrow spectral bands-one centered at 632 nm and another at 728 nm. Parrein et al follow a closely related approach in which the detection element consists of layers of thin films sandwiched with multiple transparent collection electrodes.…”

A 15nV/√Hz noise 0.2μV offset chopper conditioning amplifier for monolithic infrared sensing systems

“…A monolithically-integrated IR sensing system (IR sensor-cum-ROIC) is however more desirable because of the potential higher robustness, lower power, smaller form-factor and lower cost. This integration heretofore is not practical, in part because the IR sensor that allows for monolithic integration generally has relatively low sensitivity to IR illumination (its photovoltage signal can be < 1μV) and high noise, resulting in photovoltage outputs with very poor Signal-to-Noise Ratio (SNR) [5]. Moreover, in view of the monolithic structure where the IR sensor is fabricated directly on top of the ROIC [5], the heat dissipated by the ROIC may inadvertently degrade the performance of the IR sensor (as the ROIC may be an erroneous IR source) and further deteriorate the SNR.…”