320-Channel Dual Phase Lock-in Optical Spectrometer

TL;DR

This paper introduces a 320-channel dual-phase lock-in optical spectrometer that enables rapid, parallel phase-sensitive detection across multiple channels, significantly improving speed and noise performance for spectroscopic measurements.

Contribution

The paper presents a novel multi-channel lock-in optical spectrometer design that achieves over 100 times faster data acquisition compared to traditional methods.

Findings

Enhanced speed by more than 100x in spectroscopic data collection.

Effective noise performance analysis at 1300 nm wavelength.

Successful time-resolved measurements of quantum dots and nanocrystal films.

Abstract

The development of a multiple-channel lock-in optical spectrometer (LIOS) is presented, which enables parallel phase-sensitive detection at the output of an optical spectrometer. The light intensity from a spectrally broad source is modulated at the reference frequency, and focused into a high-resolution imaging spectrometer. The height at which the light enters the spectrometer is controlled by an acousto-optic deflector, and the height information is preserved at the output focal plane. A two-dimensional InGaAs focal plane array collects light that has been dispersed in wavelength along the horizontal direction, and in time along the vertical direction. The data is demodulated using a high performance computer-based digital signal processor. This parallel approach greatly enhances (by more than 100x) the speed at which spectrally resolved lock-in data can be acquired. The noise performance of a working system optimized for the 1300 nm wavelength range is analyzed using a laser diode light source. Time-resolved absorption traces are obtained for InAs quantum dots embedded in a GaAs matrix, and for dispersed films of PbSe nanocrystals.