Window-Region Semiconductor Laser for Stable Vertical Divergence
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Solution Overview
Problem
The semiconductor laser device in existing technologies experiences biased light intensity distribution towards the n-type cladding layer, leading to increased waveguide loss and variation in vertical divergence angle due to higher order mode mixing, which affects the stability of laser light emission.
Innovation Solution
A semiconductor laser element with a window structure is designed, featuring a resonator with a first conductivity-type cladding layer of (AlxGa1-x)0.5In0.5P, a first guide layer of (AlyGa1-y)0.5P, and a second conductivity-type cladding layer of (AlzGa1-z)0.5In0.5P, where the refractive index differences and Al composition ratios are optimized to stabilize the vertical divergence angle, and a window region is formed in the active layer to reduce light absorption and enhance energy band gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the light intensity distribution is biased toward the n-type cladding layer to reduce waveguide loss, then waveguide loss is reduced, but higher order modes are mixed which increases variation in vertical divergence angle
Solution Approach 1:
The patent applies local quality by forming a window region with different impurity concentration and energy band gap characteristics in a specific location (in the active layer near the end face) rather than uniformly across the entire structure. This localized modification allows the light intensity distribution to be adjusted locally to suppress higher order modes while maintaining overall waveguide loss reduction, thereby stabilizing the vertical divergence angle without sacrificing energy efficiency.
2Object-affected harmful factors
If a window region is formed to increase energy band gap and reduce light absorption, then light absorption is reduced, but the refractive index relationship causes biased light intensity distribution toward n-type cladding layer
Solution Approach 1:
The patent employs parameter changes by adjusting the impurity concentration in the window region to modify the energy band gap and refractive index characteristics. By carefully controlling the impurity concentration (e.g., using Zn diffusion with specific doses), the window region achieves both reduced light absorption and modified refractive index to suppress higher order modes, thereby simultaneously addressing both benefits while mitigating the adverse effect on vertical divergence angle stability.
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 stabilizes the vertical divergence angle characteristic and reduces variation in optical output power, improving the reliability and performance of the semiconductor laser element by minimizing waveguide loss and higher order mode oscillation.
Implementation Method 1
the energy band gap is increased by diffusing an impurity
Implementation Method 2
a resonator in which laser light resonates in a first direction between a front-side end face and a rear-side end face
Implementation Method 3
a technique of forming a window region in the vicinity of an end face from which light is emitted
Data Source
AI summary
A semiconductor laser element includes: a first conductivity-type cladding layer; a first guide layer disposed above the first conductivity-type cladding layer; an active layer disposed above the first guide layer; and a second conductivity-type cladding layer disposed above the active layer. A window region is formed in a region of the active layer including part of at least one of the front-side end face or the rear-side end face, the first conductivity-type cladding layer consists of (AlxGa1-x)0.5In0.5P, the first guide layer consists of (AlyGa1-y)0.5In0.5P, and the second conductivity-type cladding layer consists of (AlzGa1-z)0.5In0.5P, where x, y, and z each denote an Al composition ratio, 0<x−y<z−y is satisfied, and D/L>0.03 is satisfied, where L denotes a length of the resonator and D denotes a length of the window region in the first direction.