﻿DOI: 10.7795/720.20200618
title:	Dataset for Combining Harmonic Laser Beams by Fiber Components for Refractivity–Compensating Two-Color Interferometry

summary: 
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.

creators:
Liu, Yang, Physikalisch-Technische Bundesanstalt (PTB), Fachbereich 5.4, Interferometrie an Maßverkörperungen, Germany, and State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin, China
Röse, Anni, Physikalisch-Technische Bundesanstalt (PTB), Fachbereich 5.4, Interferometrie an Maßverkörperungen, Germany
Prellinger, Günther, Physikalisch-Technische Bundesanstalt (PTB), Fachbereich 5.4, Interferometrie an Maßverkörperungen, Germany
Köchert, Paul, Physikalisch-Technische Bundesanstalt (PTB), Fachbereich 5.4, Interferometrie an Maßverkörperungen, Germany
Zhu, Jigui; State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin, China
Pollinger, Florian, Physikalisch-Technische Bundesanstalt (PTB), Fachbereich 5.4, Interferometrie an Maßverkörperungen, Germany

license: CC-BY 4.0 International

keywords: beam properties, photonics crystal fiber (PCF), two–color interferometry, wavelength division multiplexing (WDM), photonic crystal fiber, wide-band transmission, index of refraction, polarization 

classification: INSPEC A4281C; INSPEC A4281F; INSPEC A4281D; INSPEC A0760L  

project title: Large-scale dimensional measurements for geodesy 

Acknowledgement: This dataset was obtained within the 18SIB01 GeoMetre project. This project has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme.

Funder name: European Commission


Funder ID: 10.13039/100014132

Grant number: 18SIB01 GeoMetre

link to projekt homepage: https://www.ptb.de/empir2019/geometre/home/

related objects: https://doi.org/10.1109/JLT.2019.2960473

description of the individual files:
Each data file within this dataset is related to one figure of the related publication:
Liu et al. Combining Harmonic Laser Beams by Fiber Components for Refractivity–Compensating Two-Color Interferometry. Journal of Lightwave Technology 2020, 38 (7), 1945 – 195. https://doi.org/10.1109/JLT.2019.2960473

Files with the extension DAT are space-separated tabular data which can be opened with any text editor.
Files with the extension BMP are standard image files which can be opened with most graphics programs. 

The data is grouped in folders following the structure of the publication:

\Data\III degree and stability of polarization:
	Data of section III Degree and Stability 
	..\Fig02 polarization of emitted beams
		..\..\Fig02b and Fig02c.dat
		..\..\Fig02d and Fig02e.dat
		..\..\Fig02f and Fig02g.dat
		
	..\Fig03 polarization conservation under external stress
		..\..\Fig03a.dat
		..\..\Fig03b.dat
		..\..\Fig03c.dat
		
	..\Fig04 noise induced by external stress
		..\..\Fig04b.dat
		..\..\Fig04c.dat
		..\..\Fig04c_Raw_Data.dat
		..\..\Fig04d.dat
		..\..\Fig04d_Raw_Data.dat

\Data\IV wavefront quality:
	Data of section IV Wavefront Quality
	..\Fig05 emitted beam profiles
		..\..\Fig05b.dat
		..\..\Fig05b_MM-WDM532nm.bmp
		..\..\Fig05c.dat
		..\..\Fig05c_MM-WDM1064nm.bmp
		..\..\Fig05d.dat
		..\..\Fig05d_SM-WDM532nm.bmp
		..\..\Fig05e.dat
		..\..\Fig05e_SM-WDM1064nm.bmp	
		..\..\Fig05f.dat
		..\..\Fig05f_PM-PCF532nm.bmp
		..\..\Fig05g.dat
		..\..\Fig05g_PM-PCF1064nm.bmp	

\Data\V coherence:
	Data of section V Coherence
	..\Fig07 interference contrast
		..\..\Fig07b and Fig07c.dat
		..\..\Fig07d and Fig07e.dat
		..\..\Fig07d and Fig07e.dat














