Abstract

Miniature broadband optical sources are of interest for fiber-optic gyroscopes to reduce coherent errors due to backscattering and polarization coupling. As an alternative to superluminescent diodes (SLDs), which suffer from a 300–400-ppm/°C wavelength sensitivity to temperature and spectrum sensitivity to feedback, two new types of 1060-nm broadband source involving an optically pumped Nd-doped fiber have been developed. The first relies on superfluorescence emission in a fiber provided with a high reflector on the pump input end. The onset of superfluorescence threshold was observed at P_abs ~ 70 mW, a pump power level which can be provided by a high power laser diode array. The second source is a resonant fiber laser which utilizes the inhomogeneous nature of the Nd³⁺ electronic transitions to produce a broad emission bandwidth. This fiber laser involves one high reflector bonded at each end and exhibits a much lower threshold (P_abs = 1–2 mW). With a 30-mW diode laser as a pump, a 2.5-mW output signal with a 19-nm bandwidth was observed. As expected from the thermal stability of the host, both sources exhibit a tenfold increase in spectrum stability with temperature over SLDs.

© 1988 Optical Society of America