| 摘要 |
PURPOSE:To uniformize a basic frequency of a pre-chirp pulse and also to realize simplification by dividing the production of a transmission signal into the operation of a window function and the operation of frequency modulation. CONSTITUTION:An optical VCO circuit 1 generates a periodic frequency modulation wave being a pre-chirp signal and the signal is branched into N sets of fibers by a splitter circuit 2. A circuit 3 is a circuit to generate N-bits parallel data from serial transmission data and its register has N sets of output terminals and outputs N-bits of information stored respectively. Then relevant switch circuits 4-1 to 4-N to each bit are switched for a prescribed time only and when the relevant bit is 0, the switch circuit is closed and when 1, the switch circuit is open and the result is realized by multiplying a smooth window function definitely and each output is delayed by delay fiber circuits 5-1 to 5-N and summed by a coupler 6, then the circuit configuration is simplified and the pre-chirp characteristic is adjusted. |
