Semiconductor Laser Chip Electrode Segmentation for Stray Light Control
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Solution Overview
Problem
Conventional semiconductor laser devices face issues with stray light interference and unstable servo operations due to feedback light reflections, leading to decreased S/N ratios and increased manufacturing complexity and cost when attempting to handle multiple optical disk formats.
Innovation Solution
A semiconductor laser device with a chip exposing portion on the semiconductor laser chip to absorb feedback light, preventing reflections and stray light, and incorporating optical dividers to separate light beams for stable servo operation and compatibility with multiple optical disk formats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a wire is bonded to the semiconductor laser chip surface to scatter feedback light, then reflections towards the disk are prevented, but stray light is incident on light receiving elements lowering S/N ratio
Solution Approach 1:
The electrode surface is segmented into a light incident region and a light non-incident region. The light incident region has the electrode removed or made transparent to absorb feedback light, while the light non-incident region maintains the electrode for current supply. This segmentation prevents feedback light from being reflected while avoiding creation of stray light that would interfere with light receiving elements.
Solution Approach 2:
Different regions of the electrode have different optical properties. The light incident region is designed with electrode removal or transparency to absorb feedback light, while the light non-incident region maintains high reflectance electrode material. This local differentiation allows the electrode to simultaneously prevent feedback light reflection and avoid creating harmful stray light.
2Adaptability or versatility
If wire bonding is performed at multiple points to scatter various feedback lights for multiple disk formats, then compatibility with multiple formats is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The light incident region of the electrode serves multiple functions: it absorbs feedback light from different optical disk formats (CD, DVD, Blu-ray) and provides a universal solution that does not require format-specific wire bonding. The single light incident region design handles various wavelengths and incident angles, eliminating the need for multiple wire bonding points and simplifying manufacturing while maintaining multi-format compatibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables stable servo operations and improved signal sensitivity by eliminating stray light and simplifying manufacturing processes, allowing for cost-effective production of semiconductor laser devices capable of handling various optical disk formats.
Implementation Method 1
a chip exposing portion that exposes a region of the one face where the sub-beam is incident is formed in the electrode
Implementation Method 2
optical divider provided on one face of faces of the optical element for dividing the irradiation light into a main beam and two or more sub-beams
Implementation Method 3
An electrode made of a material having high reflectance such as gold is formed on the surface of the semiconductor laser chip, and therefore, the light incident in the semiconductor laser device is reflected by the electrode
Data Source
AI summary
A semiconductor laser device includes: a semiconductor laser chip which is composed of a semiconductor substrate and a plurality of semiconductor layers stacked on an element formation face of the semiconductor substrate and which outputs an irradiation light for irradiating an optical disk; and a light receiving element which receives the irradiation light reflected by the optical disk as a feedback light. The semiconductor laser chip includes on one face thereof an electrode facing an optical element and is fixed in a package so that at least one of sub-beams reflected by the optical disk is incident on the one face. A chip exposing portion for exposing a region of the one face where the sub-beam is incident is formed in the electrode.