A new scheme based on the electrical-filtered optical heterodyne technique is proposed for measuring the tuning speed of tunable distributed Bragg reflector (DBR) lasers. In this scheme, a 10 GHz high-pass electrical filter is used and the wavelength switching time of a tunable DBR laser for different tuning frequencies corresponding exactly to different delay lines is measured. The switching time is measured to be nearly 300 ns and can be improved by reducing the equivalent resistance-capacitance (RC) time constant of the device. The distribution of the beat signal of the DBR laser in the time domain is also obtained, and is a good match with the waveforms measured using an optical filter.
Frequency response is one of the most important characteristics of photodiode (PD). The upper limitation of the bandwidth of a PD is determined by its intrinsic frequency response. Based on the extraction method to extract the intrinsic frequency response,we take a further study to analyze the impact of the reverse bias voltage and the temperature on the frequency response of PDs. With the help of physical model,the experimental data and fitted results based on the reverse bias voltage and temperature separately are discussed,then the most reliable intrinsic frequency response of a PD is obtained.
The optimal intensity noise suppression of a Fabry-Perot （FP） laser is experimentally acquired by relatively strong external optical injection locking technology. The maximum suppression is up to 9dB around the relaxation oscillation peak of the free running FP laser. We demonstrate how the injection light power and detuning frequency influence the intensity noise suppression effects. Additionally, the relationship between the optimal suppression range and the stable locking range is experimentally studied：both ranges enlarge as the injection light power increases, but the stable locking range permits larger detuning frequency at identical injection light power.
Based on the high frequency techniques such as frequency response measurement,equivalent circuit modeling and packaging parasitics compensation,a comprehensive optimization method for packaging high-speed semiconductor laser module is presented in this paper.The experiments show that the small-signal magnitude frequency response of the TO packaged laser module is superior to that of laser diode in frequencies,and the in-band flatness and the phase-frequency linearity are also improved significantly.
LIU Yu CHEN ShuoFu WANG Xin YUAN HaiQing XIE Liang ZHU NingHua
