"Picosecond Regime Optical Sampler Using Semiconductor Lasers"

[目的]本研究的目的是构建一个面包板级别的电光采样系统，以评估超短脉冲技术在10-100Gbit/S超快电子学中的能力。脉冲半导体激光器的使用是实现真正有用的测试系统的关键部分。继去年通过改进增益开关或使用光纤进行脉冲压缩来产生FWHM小于10ps的超短脉冲之后，今年的焦点集中在使用半导体激光放大器来增加脉冲能量和整形的同时。利用非线性增益动力学可以抑制通常与增益开关激光脉冲相关的长Er尾部。也就是说，当入射脉冲功率适当高时，激活介质中的布居反转主要通过主瓣的放大而消耗，而尾部仅被电子空穴对几乎耗尽的介质放大。这一想法得到了计算机模拟和实验的验证。具体地说，由于双路传输将更彻底地耗尽布居反转，因此反射波放大器(RWA)的结构在整形脉冲方面更有效。[半导体激光放大器在电光采样系统中的应用]半导体激光放大器的使用有助于提高信号功率，同时半导体激光放大器的多余噪声部分补偿了增益。理论和实验证明，选择合适的静态延迟存在一个最大化信噪比的最佳点。从实验上证实了6分贝的净增益。

[OBJECTIVE] The purpose of the present study is to construct a bread board level electro-optic sampling system in order to evaluate the capability of the ultrashort pulse technology for very fast electronics of 10-100 Gbit/s. The use of pulsed semiconductor lasers is the essential part of the presert implementation toward the realization of truly useful testing systems.[Ultrashort Pulse Generation from Semiconductor Lasers] Following the achievements of generating vey short optical pulses with FWHM less than 10 ps last year either by improving gain switching or by employing fibers for pulse compression, the focus this year is concentrated on the use of diode laser amplifier for increasing the pulse energy together with the shaping. The long er tail part usually associated with the gain switched laser pulses may be suppressed by utilizing the nonlinear gain dynamics. Namely if the incident pulse power level is properly high, the population inversion in the active medium is consumed mainly through the amplification of the main lobe, while the tail part is amplified only by the medium with almost depleted of the electron hole pairs. This idea was examined both by the computer simulation and the experiment. Specifically it was found that the configuration of reflected wave amplifier (RWA) is more efficient in shaping the pulses, because the population inversion will be more thoroughly depleted by the double path propagation.[Application of Diode Laser Ampoifier to Electro-Optic Sampling System] The use of diode laser amplifier helps the increase of signal power, meanwhile the excess noise poer from diode laser amplifier partially compensate the gain. It was examined theoretically and experimentally that the proper choice of the static retardation has an optimum point for maximizing the signal to noise ratio. Experimentally 6 dB net gain was confirmed.