Light-emitting Element Module With Inclined Window
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Solution Overview
Problem
In light-emitting element modules, particularly in optical pickup devices, the stability of laser light emitted from semiconductor lasers is compromised due to return light reflections, which affects the wavelength stability and is exacerbated by miniaturization demands.
Innovation Solution
A light-emitting element module design featuring a lid with a protrusion portion and an inclined window that increases the separation distance from the light-emitting element, reducing return light influence while maintaining module size, utilizing a lid with a thinner second portion for easier joining and ensuring mechanical strength, and optimizing the window's inclination and position to minimize diffused reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the window is installed orthogonal to the emission direction of laser light, then the structure is simple, but return light reflects back to the semiconductor laser causing wavelength instability
Solution Approach 1:
The window surface is designed with an inclination angle θ (5°≤θ≤45°) relative to the optical axis, creating an asymmetric configuration that prevents return light from reflecting back to the semiconductor laser while maintaining structural simplicity
Solution Approach 2:
The inclined window surface redirects the harmful return light away from the laser source, converting the potential harmful reflection into a beneficial arrangement where the reflected light exits the package without affecting laser stability
2Reliability
If the distance between the window and the light-emitting element is increased to reduce return light influence, then the return light impact is reduced, but the module size increases
Solution Approach 1:
Instead of increasing distance along the optical axis (one dimension), the solution utilizes the angular dimension by inclining the window surface, thereby redirecting return light without requiring additional space in the longitudinal direction
Solution Approach 2:
The window surface angle parameter θ is optimized within the range 5°≤θ≤45° to achieve effective return light redirection while maintaining compact module dimensions, balancing optical performance with size constraints
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
This configuration effectively reduces the impact of return light on the light-emitting element, stabilizes the wavelength, and allows for miniaturization without increasing the module's size, enhancing the optical characteristics and oscillation properties in atomic oscillators and electronic apparatuses.
Implementation Method 1
A surface of the window on a side of the light-emitting element is inclined with respect to a surface perpendicular to an optical axis of the light... to reduce return light returning to the light-emitting element by reflecting the light from the light-emitting element to the window
Data Source
AI summary
A light-emitting element module includes a light-emitting element that emits light, a base that has a depression portion in which the light-emitting element is accommodated, and a lid that covers an opening of the depression portion and is joined to the base. The lid includes a protrusion portion that protrudes on an opposite side to the base and has a hole through which the light passes and a window that is installed in the protrusion portion to block the hole and transmits the light. A surface of the window on a side of the light-emitting element is inclined with respect to a surface perpendicular to an optical axis of the light.