Asymmetric phase shift grating and DFB semiconductor laser

Abstract

The application discloses an asymmetric phase shift grating and a DFB semiconductor laser. The phase shift grating includes a phase shift, and a first grating and a second grating on both sides of thephase shift. The length of the first grating is greater than that of the second grating. The etching depths of the first grating and the second grating are the same and the grating periods are equal;the first grating and the second grating both include an apodization grating adjacent to the phase shift, and the duty cycle of the apodization grating gradually changes so that the refractive indexmodulation of the phase shift grating gradually decreases from the two sides toward the phase shift. This application is based on a DFB semiconductor laser of an asymmetrically structured phase shiftgrating. Under the condition that the etch depth and the grating period of the two sides of the phase shift grating are the same, the position of the phase shift is changed so that the phase shift deviates from the center of the cavity length and is deviated toward the laser output end. Asymmetric output optical power is achieved, which increases the effective output optical power of the laser; and the apodization grating is introduced into the gratings on both sides of the phase shift, which effectively reduces the effect of the spatial hole burning effect and improves the single-mode productrate of the DFB semiconductor laser.

Description

technical field [0001] The application belongs to the technical field of semiconductor lasers, and in particular relates to an asymmetric structure phase shift grating and a DFB semiconductor laser. Background technique [0002] Distributed feedback (DFB) semiconductor lasers have become an indispensable light source in optical communication networks, and play an important role in various wavelength division multiplexing systems such as DWDM and CWDM. [0003] The optical feedback of the DFB semiconductor laser is provided by the Bragg grating integrated in the laser. The grating is mostly made in the waveguide layer, and the refractive index along the cavity length direction changes periodically. The Bragg grating has different reflectivity for different modes in the laser cavity, and usually has a high reflectivity in a region near the Bragg wavelength, and a low reflectivity in a region far from the Bragg wavelength. Therefore, for the different modes existing in the las...

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Problems solved by technology

However, the highly reflective coating will bring about random phase effects, resulting in laser mode hopping

The negative impact of random phase on the laser cannot be controlled, and no effective method has been found to solve the impact of random phase

In addition, for future photonic integrated chips, that is, chips in which various photonic devices are integrated by selective area epitaxial growth technology or docking growth technology, it is impossible to achieve asymmetric output of laser light on both ends of DFB lasers by coating methods

For structure 2, the phase shift deviates from the center position to the laser output end, although it can increase the optical power at the output end, but the phase shift deviation from the center will aggravate the impact of the spatial hole burning effect and reduce the single-mode yield

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