Semiconductor Laser Electrode Recess to Keep the Emission Facet Clear
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Solution Overview
Problem
When a semiconductor laser is junction-down mounted, the bonding member such as a solder material can cover the active layer, blocking emission light and preventing sufficient light output, and existing mounting methods require submounts with specific copper plating layer dimensions, making it difficult to adapt to different semiconductor laser dimensions.
Innovation Solution
A semiconductor laser design with a conductive member that includes receding portions on the side faces of the emission facet, allowing the bonding member to be absorbed and preventing it from encroaching on the light emission facet during junction-down mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If junction-down mounting is performed with a copper plating layer on the submount to prevent short-circuit, then reliability is improved, but the bonding member may still come around the light emission facet and block emission light
Solution Approach 1:
The invention introduces a new spatial dimension by forming a receding portion that creates a stepped structure. The bonding member is confined to a lower plane (z-direction) while the light emission facet remains accessible at a higher plane, effectively separating the bonding function from the light emission function in the vertical dimension. This prevents the bonding member from blocking light without compromising electrical connection reliability.
Solution Approach 2:
The conductive member is segmented into two distinct functional zones: a first portion that provides electrical connection and heat dissipation (with the bonding member attached), and a second portion (receding portion) that recedes to prevent light blocking. This segmentation allows each portion to optimize its specific function without interfering with the other.
2Reliability
If a copper plating layer is used to prevent short-circuit, then reliability is improved, but custom submount designs with specific dimensions are required for different semiconductor laser sizes
Solution Approach 1:
The receding portion structure is incorporated into the semiconductor laser chip itself, making it a universal solution that can be applied to various semiconductor laser dimensions. Unlike custom submount designs, this feature is built into the laser chip's conductive member, allowing the same mounting approach to work across different device sizes without requiring customized submount specifications.
3Reliability
If the conductive member extends to the emission facet side, then electrical connection is improved, but the bonding member can come around and cover the active layer
Solution Approach 1:
The conductive member exhibits different spatial configurations at different locations: the first portion extends toward the emission facet to ensure excellent electrical connection and heat dissipation, while the second portion (receding portion) locally recedes to prevent light blocking. This local differentiation of spatial quality allows simultaneous optimization of both electrical performance and optical performance.
Data Source
AI summary
A semiconductor laser comprises: a semiconductor substrate; a semiconductor structure part that is formed on the substrate; a surface electrode formed on the structure part opposite to the substrate; and a conductive member formed on the surface electrode opposite to the substrate. The conductive member is such that part of or the whole of a side face thereof on an emission facet side, the side face being one side face in an x-direction parallel to an extending direction of an active layer, is formed to be away from an emission facet in the structure part toward a side of the other facet opposed to the emission facet in the x-direction. In the semiconductor laser, a receding portion is formed such that at least part of the conductive member recedes toward the side of the other facet in the x-direction from the emission facet.