Abstract

This paper reports the first demonstration of reflection gratings, operating at the important telecommunications wavelength of 1.5 m, that have been written directly into germanosilicate fibers with an ultraviolet source. Although Meltz et al.¹ have recently reported similar gratings, their results were limited to the visible region of the spectrum. In our experiments we used an intracavity frequency-doubled Ar⁺ ion laser, producing several 10's of milliwatts of power at 257.2 nm, and a single fused silica prism to generate the two overlapping writing beams. Gratings roughly 3 mm long and having reflectivities of nearly 10% have been produced, although simple scaling of our results suggests that reflectivities approaching 100% ought to be achievable. These gratings appear to be polarization-insensitive and show no detectable out-of-band loss. By using one of our gratings as an output coupler for a high-power Er3+ doped fiber laser, we have been unable to detect any degradation in the reflectivity when it is subjected to over 300 mW of infrared power for several hours. The gratings remain stable at room temperature, although our studies have shown that at 600 C the grating reflectivity decays significantly over an hour.

© 1990 Optical Society of America