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Proceedings Paper

Wavelength-tunable quasi-cw laser source for high-accuracy spectrometric measurement in the 200-nm to 500-nm region
Author(s): William S. Hartree; Evangelos Theocharous; Nigel P. Fox
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Paper Abstract

Harmonic generation of the output of a mode-locked titanium sapphire laser is a highly effective means for producing high power, quasi-cw, wavelength tunable radiation in the 200-500 nm spectral range. The laser is not truly cw, consisting of pulses at approximately 100 MHz. This paper investigates the possibility of stretching these pulses in time using a multimode optical fiber to achieve a truly cw signal: stretching of a 1.5 ps pulse to around 1 ns has been demonstrated. Non-linearity effects in the responsivity of different optical radiation detectors due to the pulsed nature of the radiation have been investigated, and no evidence for non-linearity has been seen for either silicon or GaAsP detectors at wavelengths of 300 or 360 nm within the measurement uncertainties (< 0.15%). Finally, data are presented indicating that the use of mode-locked radiation in transmittance spectrophotometry avoids the problem of interference between front and back surface reflections which has previously hindered high accuracy transmittance measurement using lasers.

Paper Details

Date Published: 8 August 2003
PDF: 9 pages
Proc. SPIE 4826, Fourth Oxford Conference on Spectroscopy, (8 August 2003); doi: 10.1117/12.514530
Show Author Affiliations
William S. Hartree, National Physical Lab. (United Kingdom)
Evangelos Theocharous, National Physical Lab. (United Kingdom)
Nigel P. Fox, National Physical Lab. (United Kingdom)

Published in SPIE Proceedings Vol. 4826:
Fourth Oxford Conference on Spectroscopy
Art Springsteen; Michael Pointer, Editor(s)

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