Open AccessChirped-grating spectrometer-on-a-chip
Author(s) -
Shima Nezhadbadeh,
Alexander Neumann,
Payman Zarkesh-Ha,
S. R. J. Brueck
Publication year - 2020
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.398072
Subject(s) - grating , optics , spectrometer , materials science , waveguide , diffraction grating , free spectral range , chip , optoelectronics , blazed grating , lithography , detector , photodetector , wavelength , physics , telecommunications , computer science
We demonstrate an on-chip spectrometer readily integrable with CMOS electronics. The structure is comprised of a SiO 2 /Si 3 N 4 /SiO 2 waveguide atop a silicon substrate. A transversely chirped grating is fabricated, in a single-step optical lithography process, on a portion of the waveguide to provide angle and wavelength dependent coupling to the guided mode. The spectral and angular information is encoded in the spatial dependence of the grating period. A uniform pitch grating area, separated from the collection area by an unpatterned propagation region, provides the out-coupling to a CMOS detector array. A resolution of 0.3 nm at 633 nm with a spectral coverage tunable across the visible and NIR (to ∼ 1 µm limited by the Si photodetector) by changing the angle of incidence, is demonstrated without the need for any signal processing deconvolution. This on-chip spectrometer concept will cost effectively enable a broad range of applications that are beyond the reach of current integrated spectroscopic technologies.