A widely tunable Ridge Width Varied Two-section partly Gain-Coupled DFB Self-pulsation Laser for Optical Microwave Generation

Abstract

The optical microwave source is the key device in the radio over fiber system and plays a more and more important role in today’s broadband all–optical wireless communication [1] especially in the in-home networks. Compared with the kind of injection mode locking in a compound cavity, the multi-section self-pulsation DFB lasers are more promising applicants for the microwave generation because of their compact sizes and easily to fabrication processes. What is more, microwave frequency can be widely tuned by the easy control of the injection DC currents of the two almost independence DFB laser sections and have potential in ultrahigh-speed even to T-Hz range [2]. The multi-section self-pulsation DFB laser is also an effective device in all-optical clock recovery in 3R regeneration (Re-amplification, Re-shaping and Re-timing) [3]. Experiment has demonstrated that a novel two-section index-coupled DFB laser with a varied ridge width can have a very wide tunable pulsation frequency range [4]. The microwave frequency can be easily tuned by the DC current injected to one of the two DFB section with a value about 2.2GHz/mA. In this paper we report the application of the varied ridge structure to a partly Gain-Coupled two-section DFB self-pulsation laser (SPL) for optical microwave generation by sidemode injection. It has an easy fabrication process and has an over 135GHz continuous microwave frequency tuning range. Successful sideband injection locking experiments were carried out by using the device. The device provides high-purity MMW signals with a timing jitter below 300fs.