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

Recently, strong demands for compactness and drastic cost reduction of optical transceivers are arising. Small Form Factor (SFF) optical transceivers are expected to meet these demands. The new conceptual optical module based on v-grooved silicon optical bench (SiOB) technology, that enables a passive alignment of optical fibres and optical devices is also expected to reduce the cost drastically. 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. Especially, it is difficult to reduce the crosstalk in a SiOB because large electromagnetic coupling exists due to the conductivity of a silicon substrate. In this paper, a newly developed, low crosstalk optical sub assembly (OSA) with a single mode fiber MT-RJ receptacle and the SFF transceiver module using it 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.