Computational effective numerical models of the active semiconductor components in the optical communication systems

Numerical modelling is an important tool for design and simulation of optical components in the optical communication systems. Signal characteristics of active devices, like distributed feedback laser and avalanche photodiode, which can be obtained from simulations, are the key for performance optical systems. Selection of appropriate numerical methods and tools leads to possibility create effective models emulating more sophisticated optical communication configurations. Sufficiently precise and time effective numerical methods are necessary to obtain characteristics compatible with real devices. Equivalent circuit models utilize sets of differential equations. The key output characteristics of the laser and avalanche photodiode are the optical power, instantaneous optical phase and electrical current at the output. Those fundamental characteristics can be utilized for determination of signal to noise ratio, impact impulse response on the bias voltage and time duration of transmitted symbol. To achieve the maximum signal to noise ratio it is necessary to suppress noise of the semiconductor laser and emit light on the maximum output power. It may be achieved when the laser lasing at the wavelength 800 nm for maximal injected current 24 mA. The 80 V reverse-bias voltage near the breakdown voltage allows maximize output electrical current, simultaneously with high bit rates around 25 Gb/s which increase impulse response of photodiode. Carefully controlling of these parameters is possible by optimization of optical communication system performance.