Temperature dependence of turn-on time delay of semiconductor laser diode: Theoretical analysis

Temperature dependence of the turn-on time delay (t(on)) of uncooled semiconductor laser diodes biased below and above threshold is analyzed in presence of data pattern effect. We show that even when the laser is biased at or slightly above threshold, the increase in temperature of operation will lead to increase in the threshold carrier (N-th) and consequently the laser diode will be biased below the threshold again and a significant value of t(on) will be produced. Thus, knowledge about a value of dc-bias current required to achieve zero t(on) within wide range of temperature degrees is important when considering uncooled laser diode in high-speed optical communication systems. The temperature dependence of t(on) is calculated according to the temperature dependence of N-th and Auger recombination coefficient (C) and not by the well-know exponentional relationship of threshold current with temperature. The temperature dependence of N-th is calculated according to the temperature dependence of laser cavity parameters. Advanced analytical model is derived in term of carrier density, recombination coefficients and the injection current (I-inj). The validity of proposed model is confirmed by a numerical method. In addition, approximated models are included where under specified assumptions the proposed model reduces to the well-known approximate models of t(on). According to our typical values and at a specified value of modulation current, the dc-bias one (I-ib) should be increased from I-ib = I-th to I-ib a parts per thousand 1.25 and 1.5I(th) in order to achieve approximately zero t(on) when the temperature increases from 25A degrees C to 55A degrees C and 85A degrees C, respectively.