Single mode fiber MT-RJ SFF transceiver module using optical subassembly with a new shielded silicon optical bench

Demand for a compact cost reduced optical transceiver has arisen. Small form factor (SFF) optical transceivers are expected to meet this demand. A new concept optical module based on V-grooved silicon optical bench (SiOB) technology, that enables a passive alignment of optical fibers and optical devices is expected to reduce the cost. MT-RJ SFF optical transceivers require this new packaging technique because the distance between input and output optical axes is shorter than conventional transceivers. However, crosstalk between a transmitter and a receiver is a big issue to be solved because the distance between optical axes of the laser diode (LD) and the photo diode (PD) is only 0.75 mm. It is difficult to reduce the crosstalk in a SiOB because large electromagnetic coupling exists due to the conductivity of a silicon substrate. A newly developed, low crosstalk optical subassembly (OSA) with a single mode fiber MT-RJ receptacle and the SFF transceiver module are reported. We have analyzed a mechanism of electrical crosstalk in a SiOB and developed a shield structure to reduce it. The crosstalk in the OSA with shielded SiOB was reduced over 20 dB compared to the unshielded SiOB.