Open AccessSimple and cost-effective thickness measurement terahertz system based on a compact 155 μm λ/4 phase-shifted dual-mode laser
Author(s) -
Han-Cheol Ryu,
Namje Kim,
Shihui Han,
Hyunsung Ko,
JeongWoo Park,
Kiwon Moon,
Kyung Hyun Park
Publication year - 2012
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.20.025990
Subject(s) - optics , terahertz radiation , beat (acoustics) , materials science , laser , direct conversion receiver , physics , homodyne detection
A simple thickness measurement method based on the coherent homodyne CW THz system was demonstrated; it does not require precise control of the frequencies of the beat source, and only accurate scanning of the optical delay line is needed. Three beat frequencies are sufficient for measuring the thickness of a sample without considering the modulo 2π ambiguity. A novel compact 1.55 μm λ/4 phase-shifted dual-mode laser (DML) was developed as an optical beat source for the CW THz system. The thickness of a sample was accurately estimated from the measurements using the proposed method. Our results clearly show the possibility of a compact, simple, and cost-effective CW THz system for practical applications.