Effect of number of quantum wells on modulation and distortion characteristics of transistor laser

Abstract

Numerical analysis on the effect of number of quantum wells (QW) on the modulation and distortion characteristics of 1300 nm Transistor Laser (TL) is reported. The terminal currents are found by using triangular charge model in the base region. The parameters such as threshold current and optical power are analyzed from the DC characteristics for different number of quantum wells. Modulation depth, frequency response are determined by providing an ac input signal with dc bias offset. It is found that the modulation depth decreases for increasing the number of quantum wells and input bias current under CE and CB configuration respectively. From this analysis, the Transistor Laser bandwidth, resonance frequency are estimated for different number of quantum wells and a maximum bandwidth of 27.5 GHz and 44.3 GHz for 25Ith are observed under CE and CB configurations respectively. Further, the distortion characteristics such as second harmonic and intermodulation products are analyzed at 2.4 GHz band for Radio over Fiber applications. The magnitude of 2HD and IMD3 components are found to decrease for increase in number of quantum wells and bias current under both CE and CB configurations. A minimum value of magnitude of 2HD components is obtained as −27.58 dBc at 25IBth and −17.82 dBc at 1.8IEth under CE and CB configuration respectively for six quantum wells in the transistor laser. Similarly, minimum value of IMD3 magnitude is obtained as − 40.47 dBc at 25IBth and − 36.91 dBc at 1.8IEth under CE and CB configuration respectively. A maximum Spurious Free Dynamic Range of 58.85 dB-Hz2/3 is predicted at 10IEth for four number of quantum wells under CE configuration.