Reducing back reflection in hybrid lasers

Abstract

In conventional hybrid lasers large back refection may lead to a degradation of relative intensity noise (RIN), linewidth broadening, mode hopping, etc. To solve the aforementioned problem a hybrid laser includes a mode converter for converting a higher-back-reflection mode of the light to a mode providing less back reflection to the gain chip. The mode converter may comprise a polarization rotator, a waveguide converter, or high-order mode converter. A routing waveguide may be provided including a phase shifter, e.g. a doped waveguide, for adjusting a cavity length of the laser cavity.

Description

TECHNICAL FIELD[0001]The present invention relates to a hybrid laser, and in particular to a hybrid laser with reduced back reflection.BACKGROUND[0002]Conventional silicon photonics-based hybrid lasers are sensitive to external feedback. Large back refection leads to a degradation of relative intensity noise (RIN), linewidth broadening, mode hopping, etc.[0003]Previous attempts at reducing back reflection include the use of an integrated isolator; however, integrated isolators on a chip are extremely difficult and expensive to implement and have large insertion loss and low isolation. Alternatively, the use of an angled coupling interface between the III-V gain chip and the silicon chip has been tried, but this increases the difficulty in aligning the III-V gain chip and the silicon chip, and the back reflection reduction is limited. Another solution includes the use of index-matching materials between the gain chip and the silicon chip, but the shortcomings include an increase in t...

AI Technical Summary

Benefits of technology

This patent is about a device that converts the way light is emitted to reduce the amount of light that bounces back to the device that detects it. This improvement can help improve the accuracy of detecting the light.

Problems solved by technology

Previous attempts at reducing back reflection include the use of an integrated isolator; however, integrated isolators on a chip are extremely difficult and expensive to implement and have large insertion loss and low isolation.

Alternatively, the use of an angled coupling interface between the III-V gain chip and the silicon chip has been tried, but this increases the difficulty in aligning the III-V gain chip and the silicon chip, and the back reflection reduction is limited.

Another solution includes the use of index-matching materials between the gain chip and the silicon chip, but the shortcomings include an increase in the packaging complexity and cost.

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