Open AccessDetection of weak near-infrared optical imaging signals under ambient light by optical parametric amplification
Author(s) -
Yi Sun,
Haohua Tu,
Sixian You,
Chi Zhang,
Yuan Zhi Liu,
Stephen A. Boppart
Publication year - 2019
Publication title -
optics letters/optics index
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.524
H-Index - 272
eISSN - 1071-2763
pISSN - 0146-9592
DOI - 10.1364/ol.44.004391
Subject(s) - optics , photomultiplier , optical parametric amplifier , materials science , lithium niobate , optical amplifier , amplifier , signal (programming language) , optical power , photodetector , optoelectronics , laser , physics , detector , cmos , computer science , programming language
We present a detection method based on optical parametric amplification to amplify and detect near-infrared (NIR) optical imaging signals. A periodically poled lithium niobate crystal is employed as an optical parametric amplifier (OPA), which provides excellent quasi-phase-matching conditions for the optical parametric amplification process. A weak reflectance imaging signal at 1465 nm is amplified by the OPA with a high gain of up to 92 dB, and the amplified optical signal is detected with a low-cost photodetector under ambient light conditions. Such a high gain leads to a detection limit of 23 pW under a 5 MHz detection bandwidth, which is remarkably lower than the theoretical value of a NIR photomultiplier tube (PMT). By exploiting the advantages of the OPA, the incident power needed for microscopy or imaging is reduced by 40-60 dB. The high imaging gain of the OPA also significantly enhances the imaging penetration depth by selectively detecting the weak signal reflected from deep tissue structures. The successful implementation of the OPA enables a robust and sensitive detection method that offers the potential to replace PMTs in imaging applications within the NIR spectral range.