title: Simple and cost-effective thickness measurement terahertz system based on a compact 1.55 μm λ/4 phase-shifted dual-mode laser.
abstract: 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.
authors.affiliation: THz Photonics Creative Research Center, ETRI, Daejeon 305-700, South Korea.
authors.forename: Han-Cheol
authors.initials: HC
authors.lastname: Ryu
authors.forename: Namje
authors.initials: N
authors.lastname: Kim
authors.forename: Sang-Pil
authors.initials: SP
authors.lastname: Han
authors.forename: Hyunsung
authors.initials: H
authors.lastname: Ko
authors.forename: Jeong-Woo
authors.initials: JW
authors.lastname: Park
authors.forename: Kiwon
authors.initials: K
authors.lastname: Moon
authors.forename: Kyung Hyun
authors.initials: KH
authors.lastname: Park