Development of a frequency-shifted feedback fiber laser at 777.5 nm for range sensing applications

Abstract

A frequency-shifted feedback (FSF) laser in combination with an interferometer is a very accurate range sensing tool. In this paper, an FSF fiber laser with an output spectrum in the 777.5 nm range is presented. The cavity of the laser works in the 1555 nm range, enabling the use of cheap standard telecom products. Since a wavelength of 1555 nm is not detectable with silicon semiconductor devices, the output of the laser is frequency-doubled by a periodically poled lithium niobate (PPLN) crystal, which shifts the output spectrum from 1555 nm to 777.5 nm. It could be shown that frequency doubling is a feasible way to shift the output spectrum of the laser to a range which is detectable by silicon, without destroying the special properties of the FSF laser.