Phase shift optical grating of symmetric structure and DFB semiconductor laser device

Abstract

The application discloses a phase shift optical grating of a symmetric structure and a DFB semiconductor laser device. The phase shift optical grating comprises a phase shift structure arranged at a central position of the phase shift optical grating and a first optical grating and a second optical grating positioned at two sides of the phase shift structure; the first optical grating and the second optical grating are the same in length, etching depth and optical grating period; the first optical grating is constantly invariant in duty ratio, the second optical grating comprises an apodized optical grating, the duty ratio of the apodized optical grating gradually changes along an axial direction of the optical grating, and the second optical grating is weaker than the first optical grating in refractive index modulation intensity. In the DFB semiconductor laser device based on the phase shift optical grating of the symmetric structure disclosed in the invention, the apodized optical grating is introduced in the second optical grating in a condition that the optical gratings at the two sides of the phase shift structure remain unchanged in terms of length, etching depth and period; asymmetry of phase shift optical grating coupling factors at the two sides can be realized, asymmetry of output light power can be realized via the DFB semiconductor laser device, and effective output light power of the laser device can be increased.

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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