1.55 μm MQW-DFB Q-switch two-section laser for high frequency-short pulse generation

The generation of short optical pulses at 1.55 μm with a high frequency repetition is of great interest for future optical communication systems as Optical Time Division Multiplexed (OTDM) systems. Such sources have been widely investigated but most of the techniques (active, passive and hybrid modelocking...) are often limited by a low output optical power and a small tunability of the repetition rate. To overcome these limitations and to allow a flexible soliton transmission, we developed a two-section MQW-DFB laser diode structure based on the Q-switching effect. The two-segment configuration consists of a long length (gain section) combined to a short length (saturable absorber section). The gain section is biased in a CW forward mode while a modulated voltage, around a value lower than the built-in voltage (0.8 V for 1.53 μm), is applied to the saturable absorber. The LD fabrication and characteristics are discussed