Phase shift grating of asymmetric structure and DFB semiconductor laser

Abstract

The invention discloses a phase shift grating of an asymmetric structure and a DFB semiconductor laser. The phase shift grating comprises a phase shift structure positioned in a non-center position ofthe phase shift grating and first and second gratings positioned at the two sides of the phase shift structure respectively, the grating period and length of the first grating are the same with thoseof the second grating respectively, the duty ratio of the first grating is the same with that of the second grating or the sum of the duty ratios of the first and second gratings equals 1, the etching depth of the side, close to the phase shift structure, of each of the first and second gratings is lower than that of the side far from the phase shift structure. Thus optical power can be output inan asymmetric way, and the output optical power of the laser is improved; and refractive index modulation near the phase shift structure is reduced, influence of spatial hole burning effect is weakened effectively, and the single-mode stability of the laser is 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...

AI Technical Summary

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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