THERMAL-STABILITY OF BIAS POINT OF PACKAGED LINEAR MODULATORS IN LITHIUM-NIOBATE

The thermal stability of the bias point of packaged, passively biased, X-cut LiNbO3 interferometric modulators is described, Absolute stabil ity is assessed and a comparison is made of stability before and after laser ablation adjustment used to tune the bias point to linear opera tion (90 degrees phase angle). Ablation is shown to be successful in s etting the bias angle to +/-1 degrees of the desired value. The angle remained stable to a total variation of <5 degrees over -25-+42 degree s C both before and after ablation. All the observed angular changes w ith temperature were in the range 0.02-0.09 deg/degrees C. The effect of humidity in the package on modulator stability is characterized and then minimized for the actual devices.