Cost-Effective Optical Sub-Assembly Using Lens-Integrated Surface-Emitting Laser

A cost-effective optical sub-assembly (OSA) for high-speed optical interconnections using lens-integrated surface-emitting lasers (LISELs) is demonstrated. Two concepts of the OSA, one based on a direct-modulation (DM)-LISEL and the other based on a continuous-wave (CW)-LISEL for a silicon-photonics (SiP) platform, are proposed. The design parameters of the integrated lens that enable low fiber-coupling loss and the SiP platform are described. Coupling losses, as low as 4.9 dB for the single mode fiber and 4 dB for the SiP platform, were experimentally confirmed. Furthermore, theoretical and experimental evidence that demonstrates the OSA does not require an optical isolator (i.e., it is “isolator-free”) is presented. A DFB laser used for the LISEL had a low relative intensity noise (less than -140 dB/Hz), even with a back reflection of more than -20 dB. For non-Hermetic packaging, 500 h, 85°C/85% relative humidity storage tests experimentally demonstrated no degradation in the lasing characteristics.