Abstract

Recently, interest has emerged in developing glass waveguide amplifiers. Such components are useful in monolithic integration of sources, amplifiers, and other optical circuits. Ion-exchanged waveguide lasers operating at 1.06 and 1.3 μm have already been demonstrated. However, there are very few reports of amplification in glass waveguides. By using Ag⁺-Na⁺ exchange, 3 dB gain has been reported in two different glasses at 1.06 μm wavelength. In this work, we report 15-dB amplification in K⁺-Na₊ ion-exchanged channel waveguides fabricated by thermal diffusion from KNO₃ melt in a 2% Nd³⁺-doped silicate glass. We used the 532 nm radiation from a frequency-doubled, Q-switched and mode-locked Nd:YAG laser as the pump. At this wavelength, the 8 mm long waveguides absorb 5% of the pump power. Apart from the strong fluo­rescence at 1.06 μm, a weak fluorescence at 1.3 μm and some visible light due to the upconversion processes were also observed. For amplification measurements, the residual 1.064 μm radiation from the laser was attenuated and served as the signal. The two collinear beams were simulta­neously coupled into the guides polished at both the ends, and the output signal was measured with and without the pump. We obtained up to 15-dB amplification with 100 mW peak pump power incident at the input without observing any saturation. To the best of our knowledge this is the largest amplification yet reported in these guides. The amplification factor is likely to increase further with an 808 nm diode pump where the absorption is larger.

© 1992 Optical Society of America