Semipolar GaN Laser Diode Polarization and Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing laser technologies, particularly those producing blue and green light, face inefficiencies, large size, high cost, and fragility due to the use of gas lasers and early solid-state lasers, which limit their broader deployment beyond scientific and medical applications.
Innovation Solution
The development of laser devices using semipolar oriented gallium and nitrogen containing substrates, such as GaN, with specific orientations and configurations, including laser stripe regions and cladding layers, to achieve high polarization ratios and efficient light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If gas laser designs (Ar-ion laser) are used to produce blue and green light, then highly directional and focusable light with narrow spectral output is achieved, but wall plug efficiency is poor and device size is large
Solution Approach 1:
The patent changes the fundamental operating parameters by transitioning from gas laser medium to semiconductor laser diode medium, operating in the infrared range (780-1064 nm) and using nonlinear optical crystals for frequency conversion. This parameter change enables wall plug efficiency improvement from <1% to >5% while maintaining directional beam quality
Solution Approach 2:
The patent introduces nonlinear optical crystals (frequency conversion crystals) as intermediary elements that convert infrared laser light to visible blue and green wavelengths. This intermediary approach allows the semiconductor laser diode to achieve visible light output while maintaining the efficiency benefits of direct diode pumping
2Use of energy by moving object
If lamp pumped solid state lasers with second harmonic generation are used, then wall plug efficiency improves to ~1%, but device size increases and cost increases
Solution Approach 1:
The patent extracts and eliminates the lamp pumping stage and energy storage crystal from the laser system, transitioning directly to diode pumping of the solid state gain medium. This extraction removes the bulky lamp housing and associated thermal management requirements, reducing overall device size while maintaining efficiency
Solution Approach 2:
The patent replaces the mechanical lamp pumping system with an electrical diode pumping system, substituting a compact semiconductor device for a bulky optical pumping arrangement. This substitution dramatically reduces device size and improves electrical-to-optical conversion efficiency
3Use of energy by moving object
If diode pumped solid state lasers with SHG are used, then wall plug efficiency improves to 5-10%, but system cost increases and temperature control requirements increase complexity
Solution Approach 1:
The patent changes the operating temperature parameters by designing the semiconductor laser diode and nonlinear optical crystals to operate at elevated temperatures (up to 80°C or higher), eliminating the need for complex active temperature control systems while maintaining laser performance and frequency conversion efficiency
4Volume of stationary object
If directly doubled diode lasers are used, then efficiency and size are improved, but severe sensitivity to temperature limits application
Solution Approach 1:
The patent changes the temperature operating parameters by designing the laser diode and frequency conversion crystal assembly to operate stably at elevated temperatures (up to 80°C or higher), fundamentally altering the temperature sensitivity profile and enabling reliable operation without active temperature control
Solution Approach 2:
The patent uses temperature-insensitive laser diode designs and frequency conversion crystal selections that replicate the performance characteristics of temperature-controlled systems without requiring the control infrastructure, effectively copying the desired temperature stability through material and design selection rather than active control
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
These devices offer improved efficiency, reduced size, and increased deployment possibilities by enhancing material quality and design flexibility, enabling more effective and compact high-power laser diodes with enhanced gain properties.
Implementation Method 1
laser stripe region is formed overlying a portion of the semipolar surface. The laser stripe region is characterized by a cavity orientation substantially parallel to the projection of the c-direction
Implementation Method 2
the polarization of the emitted radiation is determined by the birefringent properties of the laser stripe waveguide
Data Source
AI summary
Laser devices formed on a semipolar surface region of a gallium and nitrogen containing material are disclosed. The laser devices have a laser stripe configured to emit a laser beam having a cross-polarized emission state.