학술논문
Combining Harmonic Laser Beams by Fiber Components for Refractivity–Compensating Two-Color Interferometry
Document Type
Periodical
Author
Source
Journal of Lightwave Technology J. Lightwave Technol. Lightwave Technology, Journal of. 38(7):1945-1952 Apr, 2020
Subject
Language
ISSN
0733-8724
1558-2213
1558-2213
Abstract
A perfect spatial overlap with multiple beams of different wavelengths is a prerequisite for multi–wavelength interferometry. Beam combination with the help of fibers seems to be an interesting method for this. We investigated three different types of fiber components, multi–mode wavelength division multiplexers (MM–WDMs), single–mode wavelength division multiplexers (SM–WDMs), and endlessly single–mode polarization maintaining photonic crystal fibers (PM–PCFs). All three seem potential candidates for a perfect spatial overlap of laser beams separated by an octave, i.e. fundamental and harmonic beams. We performed an experimental study on the impact of these components on polarization, wavefront, and coherence. These properties are essential for high–accuracy interferometry. As a test system, we used the fundamental and second harmonic beam of a Nd:YAG laser system at 1064 and 532 nm as a popular system in two–color interferometry for intrinsic refractive index compensation. The experimental results show the potential of PM–PCFs for this challenging application.