100 Gb/s Multichannel TOSA With Low Tracking Error at the Industry Operating Temperature

Tracking error is a crucial metric for assessing optical alignment changes in transmitter optical subassemblies (TOSAs) under varying temperatures. We present a 100 Gb/s four-channel TOSA developed for industrial temperature ranges (– $40~^{\circ }$ C– $+ 85~^{\circ }$ C), featuring enhanced Z-sleeve thickness (0.45 mm) and optimized optical alignment. Finite-element analysis (FEA) showed that this increase reduced maximum stress from 150 to 94 MPa and displacement from 5.5 to $3.6~\mu $ m under identical shear loading by increasing the Z-sleeve thickness from 0.35 to 0.45 mm. Meanwhile, the root mean squares (rms) displacement ranges from 55.8 to $7.6~\mu $ m, achieving quasi-coaxial beam alignment. Moreover, thermal characterization revealed that the optimized 0.45 mm configuration consistently maintained tracking errors below 0.4 dB across all channels and temperatures. These results confirm that the dual strategy of mechanical reinforcement and precise optical path alignment effectively improves thermal stability, meeting the stringent requirements of high-density wavelength division multiplexing (WDM) systems for data centers and 5G/6G applications.