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Proceedings Paper

Highly repetitive low-coherence interferometry with time-stretch technique
Author(s): Masaharu Hoshikawa; Katsuhiro Ishii; Takeshi Makino; Takahiro Hashimoto; Hideaki Furukawa; Naoya Wada
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Paper Abstract

We construct highly repetitive low-coherence interferometer using time-stretch technique and confirm its basic characteristics. The experimental system consists of a mode-locked laser diode (MLLD), a time-stretcher, an optical interferometer, a photodiode (PD), and a real-time oscilloscope. The ultra-short pulse from MLLD was passed through a dispersion flat fiber to generate supercontinuum light with 23.5 nm wavelength bandwidth. Repetition frequency of the laser pulse is set to be 10 MHz by the LiNbO3 modulator, and then it feeds to a time-stretcher composed of a dispersion compensation fiber (DCF) with a wavelength dispersion of 8959 ps2. The pulse width after passing through the timestretcher is 28.2 ns. The fiber-optic Michelson interferometer consists of a 50:50 optical fiber coupler, two collimating lenses, an objective lens and two reflective mirrors. Interference signals are detected by a photodiode (32 GHz) and recorded by a real-time oscilloscope (16 GHz, 50 GS/s). The temporal profile of the recorded interference signal is converted to an optical frequency profile. The optical path length difference is determined by Fourier transform of the spectrum. We demonstrate a preliminary measurement on the experimental system. The calculated path length difference agrees well with the actual set values. It is confirmed that the optical path length difference can be measured at a high repetition rate of 10 MHz. It is shown that the degradation of the interference signal can be prevented by considering the second order of the group delay of the DCF.

Paper Details

Date Published: 21 June 2019
PDF: 6 pages
Proc. SPIE 11056, Optical Measurement Systems for Industrial Inspection XI, 1105644 (21 June 2019); doi: 10.1117/12.2525939
Show Author Affiliations
Masaharu Hoshikawa, The Graduate School for the Creation of New Photonics Industries (Japan)
Hamamatsu Photonics KK (Japan)
Katsuhiro Ishii, The Graduate School for the Creation of New Photonics Industries (Japan)
Takeshi Makino, National Institute of Information and Communications Technology (Japan)
Takahiro Hashimoto, National Institute of Information and Communications Technology (Japan)
Hideaki Furukawa, National Institute of Information and Communications Technology (Japan)
Naoya Wada, National Institute of Information and Communications Technology (Japan)


Published in SPIE Proceedings Vol. 11056:
Optical Measurement Systems for Industrial Inspection XI
Peter Lehmann; Wolfgang Osten; Armando Albertazzi Gonçalves Jr., Editor(s)

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