On-chip optical spectrometer based on GaN wavelength-selective nanostructural absorbers

A spectrometer concept based on wavelength-selective semiconductor photodiodes is proposed and demonstrated. The absorption properties of individual photodiodes were tuned via local strain engineering in nanostructured InGaN/GaN. By varying the diameters of individual nanopillars, the cutoff wavelen...

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Bibliographic Details
Published in:Applied physics letters 2020-02, Vol.116 (8)
Main Authors: Sarwar, Tuba, Cheekati, Srinivasa, Chung, Kunook, Ku, Pei-Cheng
Format: Article
Language:English
Subjects:
Absorption
Algorithms
Applied physics
Gallium nitrides
Light sources
Matched pursuit
Photodiodes
Selectivity
Semiconductors
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Summary:A spectrometer concept based on wavelength-selective semiconductor photodiodes is proposed and demonstrated. The absorption properties of individual photodiodes were tuned via local strain engineering in nanostructured InGaN/GaN. By varying the diameters of individual nanopillars, the cutoff wavelengths of absorption were varied across the chip. The intrinsic wavelength selectivity is insensitive to the incident angle of light. The top-down fabrication process shown in this work is also compatible with scalable manufacturing. A proof-of-concept spectrometer was demonstrated based on 14 photodiodes, without any external optics or spectral filtering components, in the wavelength range of 450–590 nm. Using a non-negative least squares algorithm enhanced by orthogonal matching pursuit, the spectrum of a test light source was reconstructed.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.5143114