The function of optical transceiver module is to perform photoelectric conversion, and its internal TOSA, ROSA and BOSA are the key components to realize the photoelectric conversion function. The optical device is composed of transmitter and receiver to complete the optical-electrical or electrical-optical conversion of optical signals.
The interior is composed of optical devices, functional circuits and optical interfaces. The optical device is the main component of the optical transceiver module.
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Photodetector, the main device of ROSA, is mainly used to convert optical signals into electronic signals through the photoelectric effect. The common photodetectors in optical communications are PIN photodiodes and avalanche photodiodes (APDs). APDs are high-sensitivity photodetectors that use the avalanche multiplication effect to double the photocurrent. Compared with PIN photodiode, the receiving sensitivity of APD can be improved by 6~10dB.
The weak signal current generated by the photodetector is converted into a signal voltage of sufficient magnitude by the preamplifier TIA, and then output. TIA is actually a voltage converter, which converts electro-optic current into voltage.
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At this time, the voltage signal output by the TIA is still an analog signal, which needs to be converted into a digital signal before the signal processing circuit can recognize it. The function of the Poster Amplifier behind the TIA is to convert signals of different amplitudes into digital signals with the same amplitude.
After introducing TOSA and ROSA, let's take a look at what is BOSA?
With the development of process level technology, the modules can be made smaller. TOSA and ROSA integrate the transmission and reception of light (LD and PIN/APD) through the coaxial coupling process, plus splitters, optical fibers and other components, called BOSA (Bi-Directional Optical Sub-Assembly).
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