Optical damage resistant Ti-diffused Zr/Er-codoped lithium niobate strip waveguide for high-power 980 nm pumping

Abstract

Ti⁴⁺-diffused Zr⁴⁺/Er³⁺-codoped LiNbO₃ strip waveguide was fabricated on an X-cut LiNbO₃ substrate by thermal diffusion in sequence of Er³⁺, Zr⁴⁺ and Ti⁴⁺. Secondary ion mass spectrometry study shows that the Ti⁴⁺ ions follow a sum of two error functions in the width direction and a Gauss function in the depth direction of the waveguide. Both Er³⁺ and Zr⁴⁺ profiles follow the desired Gauss function, and entirely cover the Ti⁴⁺ profile. Optical study shows that the waveguide is TE or TM single mode at 1.5 μm wavelength, and has a loss of 0.3 (0.5) dB/cm for the TM (TE) mode. In the case of 980 nm pumping, the waveguide shows stable 1547 nm signal output under high-power pumping without optical damage observed, and a net gain of 1.1 dB/cm is obtained for the available pump power of 120 mW.

High optical gain in erbium-doped potassium double tungstate channel waveguide amplifiers

“…Yb co-doping usually comes at the cost of lower total gain, because part of the pump power absorbed by Yb ions is followed by intrinsic decay rather than being transferred to Er ions. Erbium doped into crystalline materials has been the subject of recent investigations to increase the maximum achievable gain in waveguide amplifiers [12,13]. Recently, a gain of 100 dB/cm has been reported in a single-crystal erbium chloride silicate nanowire [14].…”