Spectral line

Quantum mechanics

Engineering

Photodetector

Bandwidth (computing)

Materials science

Infrared

Fourier transform spectroscopy

Telecommunications

Computer science

Physical chemistry

Physics

Nanotechnology

Optics

Astronomy

Photodiode

Miniaturization

Spectrometer

Electronics

Spectral resolution

Chemistry

Fourier transform infrared spectroscopy

Optoelectronics

Fourier transform

Electrical engineering

Nature Photonics

Extreme miniaturization of infrared spectrometers is critical for their integration into next-generation consumer electronics, wearables and ultrasmall satellites. In the infrared, there is a necessary compromise between high spectral bandwidth and high spectral resolution when miniaturizing dispersive elements, narrow band-pass filters and reconstructive spectrometers. Fourier-transform spectrometers are known for their large bandwidth and high spectral resolution in the infrared; however, they have not been fully miniaturized. Waveguide-based Fourier-transform spectrometers offer a low device footprint, but rely on an external imaging sensor such as bulky and expensive InGaAs cameras. Here we demonstrate a proof-of-concept miniaturized Fourier-transform waveguide spectrometer that incorporates a subwavelength and complementary-metal-oxide-semiconductor-compatible colloidal quantum dot photodetector as a light sensor. The resulting spectrometer exhibits a large spectral bandwidth and moderate spectral resolution of 50 cm-1 at a total active spectrometer volume below 100 μm × 100 μm × 100 μm. This ultracompact spectrometer design allows the integration of optical/analytical measurement instruments into consumer electronics and space devices.

Integrated photodetectors for compact Fourier-transform waveguide spectrometers