RESUMO
We have developed a 4 × 25 Gb/s ROSA (receiver optical sub-assembly) module for 100G Ethernet optical transceiver. This ROSA module has very large alignment tolerance of more than ± 250 µm between the optical DMUX (demultiplexer) and four photodiodes, for the reason it has the advantage of being easily assembled. The large alignment tolerance can be attributed to the dimensional tolerant optical DMUX, which is composed of four thin film filters attached to a parallelogram-shaped optic block. Since it is important to define the fabrication specifications for the dimension of the optic block, we analyze dimensional tolerance for the optic block using three-dimensional simulation. This parallelogram-shaped optical DMUX permits length tolerance of ± 300 µm and angular tolerance of ± 0.1°. The fabricated optical DMUX is estimated to have the angular error of less than 0.09°.
RESUMO
We propose a self-wavelength initialization method for the waveguide Bragg-grating based tunable external cavity laser. Reflection characteristics of the Bragg-grating, and the wavelength routing property in the wavelength division multiplexing-passive optical network (WDM-PON) were used in our proposed method. By adding a cost-effective and low- power broadband light source in the central office, the tunable laser can align its output wavelength with the wavelength at the center of the pass band of the WDM multiplexer. This method can be applicable for the Bragg-grating based tunable laser, which is placed either in the central office or in the subscriber region. The operating principle and the feasibility of the proposed method were described by evaluating the transmission performance. By using our initialization method, a tunable laser with a Bragg-grating can be used as a true colorless light source for the WDM-PON.
