how can i transmit two audio channel in digital scheme using single optical fiber? please help me!!

 

Use a TOSLINK transmitter and receiver such as found here.

 

thank! but all that TOSLINK transmiter are module, me i want to start from circuit design

 

So you need a two channel serial time-division multiplexer. Typically you would convert the analog signals to digital words at a rate sufficient to exceed the Nyquist minimum for the highest audio frequency of interest. Then you would send a sync word, then the channel 1 digital word, then the channel 2 digital word, then repeat.

 

how about synchronization at the receiving end? since there is no way to send a separate clock via optical fiber..

 

You encode the clock with the data.

http://www.atmel.com/images/doc9164.pdf

 

how about the technique of multiplexing and demultiplexing of the two channels?

 

how about the technique of multiplexing and demultiplexing of the two channels?

That multiplexed signal is what is transmitted by the Manchester code.