Fiber grating coupled light source capable of tunable, single frequency operation

摘要: Fiber Bragg grating coupled light sources can acheive tunable single-frequency (single axial and lateral spatial mode) operation by correcting for a quadratic phase variation in the dimension using an aperture stop. The output of quasi-monochromatic source such as Fabry-Perot laser diode is astigmatic. As consequence astigmatism, coupling geometries that accommodate transverse numerical are defocused dimension, even apsherical optics. mismatch produces feedback along axis at facet excites modes higher order than TM00. Because instability entails excitation submodes, single frequency also accomplished fiber gratings whose bandwidth narrower submode spacing. This technique particularly pertinent to use lensed lieu discrete Stable device requires overall match between fed-back signal output. acts phase-preserving mirror when condition met precisely. phase-match maintained throughout tuning range matching mode wavelength passband center grating.