Enhanced direct modulation bandwidth in a tunable DBR laser with an equivalent phase shift grating

Abstract

A high speed directly modulated and tunable distributed Bragg reflector laser is proposed based on an equivalent phase shift Bragg grating. By inserting a uniform waveguide in the middle of Bragg grating section, a notch is formed on reflectivity spectrum of the grating, and the photon-photon resonance (PPR) effect could then be introduced to extend modulation bandwidth. An independent electrode is also added for controlling the equivalent phase shift, which plays a key role in the design to introduce the PPR effects, and ensure compatibility with wavelength tuning. Stability, tunability and small signal response of the laser are numerically investigated, 40 GHz direct modulation bandwidth and 7 nm tuning range are obtained, indicating that the laser designed could achieve a large modulation bandwidth within a certain wavelength tuning range.