1. Field
The following description relates to an optical communication module, and more particularly, to an optical communication module which uses a single optical fiber to make bidirectional communication or multiplexing communication.
2. Description of the Related Art
A conventional bidirectional optical transceiver module is typically configured such that an optical filter is provided in a metal housing and a TO-Can type optical transmitter package and a TO-Can type optical receiver package are provided in an active alignment manner and fixed to the metal housing by a laser welder.
Since two TO-Can type packages are provided in an active alignment manner by the laser welder, the bidirectional optical transceiver module can obtain a maximum optical coupling efficiency but requires a number of process steps resulting in a low production.
For example, U.S. Pat. Nos. 7,013,056, 7,040,816, US 2006/0115207 and US 2006/0110094 disclose that a lens or an optical filter is mounted on a V-groove or a recess which is formed on a substrate, such as a silicon optical bench (SiOB). Further, an output optical signal of an optical transmitter passes through a 45-degree optical filter, and an input optical signal is reflected by an inclined surface of the optical filter and is converted in optical path by 90 degrees. The converted input optical signal is reflected by the inclined surface of the V-groove of the SiOB and is coupled to an optical receiver.
However, the conventional bidirectional optical transceiver module thus configured may experience severe optical/electrical crosstalk since the optical transmitter and the optical receiver are provided on the top surface of the same substrate. Furthermore, since the optical coupling is made using the inclined surface of V-groove of SiOB, the optical coupling efficiency may be low and the alignment tolerance may be small.
In addition, if such a bidirectional optical transceiver module as described above is applied to high-speed signal transmission, the above-mentioned crosstalk may become more significant. Further, since a photodiode chip of the optical receiver has such a small active region that the coupling efficiency between the optical receiver and the optical filter becomes lower, this type of a bidirectional optical transceiver module is not appropriate for high-speed signal transmission.