Open AccessDetection sensitivity of laser feedback interferometry using a terahertz quantum cascade laser
Author(s) -
James Keeley,
Karl Bertling,
Pierluigi Rubino,
Yah Leng Lim,
Thomas Taimre,
Xiaoqiong Qi,
Iman Kundu,
L. H. Li,
D. Indjin,
Aleksandar D. Rakić,
Edmund H. Linfield,
A. G. Davies,
J. E. Cunningham,
Paul Dean
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.44.003314
Subject(s) - optics , quantum cascade laser , interferometry , laser , terahertz radiation , cascade , sensitivity (control systems) , far infrared laser , distributed feedback laser , physics , materials science , optoelectronics , chemistry , chromatography , electronic engineering , engineering
We report on the high detection sensitivity of a laser feedback interferometry scheme based on a terahertz frequency quantum cascade laser (QCL). We show that variations on the laser voltage induced by optical feedback to the laser can be resolved with the reinjection of powers as low as ∼-125 dB of the emitted power. Our measurements demonstrate a noise equivalent power of ∼1.4 pW/√Hz, although, after accounting for the reinjection losses, we estimate that this corresponds to only ∼1 fW/√Hz being coupled to the QCL active region.