Abstract

Optical injection locking has shown many advantages such as reducing the noise of a slave laser, reducing the laser linewidth, improving the bandwidth and suppressing the frequency chirp [1, 2]. Achieving a locked state often requires a tunable external cavity laser or a well-matched DFB laser since the operating wavelength and polarization of the master laser and the slave laser must be matched. In this paper, we demonstrate a monolithic optical injection locking (MOIL) DFB laser based on four phase-shifts (4PS) sampling sections. Based on the 4PS structure, the lasing wavelength can be precisely controlled by designing the sampling period, meanwhile, the effective grating coupling coefficient κof the +1^st channel is significantly enhanced, equal to 0.9 times that of a uniform seed grating [3]. The device is based on a sidewall grating structure, requiring only one metalorganic vapor-phase epitaxy (MOVPE) step and one III-V material etching step to complete the fabrication process.

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