Asymmetrically-structured phase-shifting grating and DFB (distributed feedback) semiconductor laser

Abstract

The present application discloses an asymmetrically-structured phase-shifting grating and a DFB (distributed feedback) semiconductor laser. The phase-shifting grating comprises a phase-shifting structure, a first grating and a second grating, wherein the phase-shifting structure is located at the non-center position of the phase-shifting grating, and the first grating and the second grating are located at two sides of the phase-shifting structure; the etching depth of the first grating is equal to the etching depth of the second grating; the grating duty ratio of the first grating is equal tothe grating duty ratio of the second grating, or the sum of the grating duty ratios of the first grating and second grating is equal to 1; the length of the first grating is different from the lengthof the second grating; two sides in the first grating and the second grating, which are adjacent to the phase-shifting structure, are a first chirp grating and a second chirp grating respectively; thefirst chirp grating and the second chirp grating are symmetrically distributed along the phase-shifting structure; and the grating period of the first chirp grating and the second chirp grating gradually changes along the direction of the phase-shifting structure. With the asymmetrically-structured phase-shifting grating of the invention adopted, the asymmetric output of optical power can be realized, so that the output optical power of the laser can be improved; and refractive index modulation near the phase-shifting structure can be decreased, and therefore, the influence of a spatial hole-burning effect can be effectively reduced, and the single-mode stability of the laser can be improved.

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] For active optical communication devices, whether in optical communication networks or in photonic integrated chips, distributed feedback (DFB) semiconductor lasers are favored due to their good single-mode characteristics. In the early DFB semiconductor lasers, the refractive index was periodically and uniformly modulated. This kind of lasers symmetrically had two modes with the same cavity loss and the lowest loss on both sides of the Bragg wavelength, which is called the degeneracy of the two modes. The two-mode de...

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Problems solved by technology

[0007] For structure 1, if the laser is a discrete device, it is possible to coat one end face of the laser with a high reflective film (HR) and the other end face with an antireflection film (AR) to distribute the output laser power of the two end faces of the laser, but The high reflection film will bring about random phase effects, leading to mode hopping of the laser, and the negative impact of random phase on the laser cannot be controlled, and no effective solution to the effect of random phase has been found yet

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, reducing single-mode stability and yield

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