Fibre interferometer for multi-wavelength interferometry with a femtosecond laser

• Published in: Journal of optics. A, Pure and applied optics Vol. 7; no. 6; pp. S415 - S419
• Main Authors: Towers, C E, Reid, D T, MacPherson, W N, Maier, R R J, Towers, D P
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Bristol IOP Publishing 01.06.2005; Institute of Physics
• Subjects: Applied sciences; Circuit properties; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Fiber-optic instruments; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Integrated optics. Optical fibers and wave guides; Interferometers; Optical and optoelectronic circuits; Optical instruments, equipment and techniques; Other fiber-optical devices; Physics; Optical interferometry; Phase measurement; Interferometer; interferometry; Interferogram; Bragg grating; Experimental study; Grating in fiber; Spectral analysis; Ultrashort pulse; fringe analysis; Pulsed laser; Simultaneous measurement; Metrology; fs range; Optical fiber
• ISSN: 1464-4258; 1741-3567
• DOI: 10.1088/1464-4258/7/6/024

In this paper we propose a novel fibre interferometer for the simultaneous measurement of optical phase at multiple wavelengths generated within the spectral envelope of a femtosecond laser. The use of narrow bandwidth fibre Bragg gratings allows particular wavelengths to be selected with sufficiently narrow bandwidth to give the necessary coherence length for interferometric phase measurements over practical distances exceeding 30 mm. Multi-wavelength interferometry provides a means of making absolute measurements by extending the unambiguous measurement range beyond the wavelength of light. Preliminary experimental results are presented for a two-wavelength sensor where an absolute range of 0.13 mm with 3 nm resolution has been achieved producing a dynamic range of 43 000:1. This approach has the potential to be applied to high speed transient events.