Semiconductor Laser Diode with Integrated Bragg Reflector
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Solution Overview
Problem
High-power semiconductor laser diodes with wide emission spectra degrade beam quality when power is increased through space multiplexing, making them unsuitable for direct material processing applications, and existing stabilization methods are complex, costly, and require external components.
Innovation Solution
A semiconductor laser diode with a Bragg reflector mirror integrated directly into the chip, using etched terminal facets and a passivation layer to reduce residual reflectivity and stabilize the emission wavelength, eliminating the need for external stabilizers and allowing efficient wavelength multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If space multiplexing is used to increase power output, then power is improved, but beam quality deteriorates
Solution Approach 1:
The patent transitions from spatial multiplexing to spectral multiplexing by introducing wavelength-selective distributed Bragg reflectors (DBRs) with different spectral characteristics. Each laser diode emits at a slightly different wavelength, and the DBRs are designed to reflect specific wavelength ranges, enabling power combination in the spectral domain while maintaining beam quality through precise wavelength control
2Stability of the object's composition
If external volumetric stabilizers are used to stabilize emission wavelength, then wavelength stability is improved, but device complexity increases
Solution Approach 1:
The patent merges the wavelength stabilization function directly into the laser diode chip by integrating distributed Bragg reflectors (DBRs) as the cavity mirrors. This monolithic integration eliminates the need for separate external stabilizers such as gratings or etalons, reducing mechanical complexity while maintaining narrow spectral emission through the wavelength-selective DBR design
Solution Approach 2:
The laser diode structure itself provides wavelength stabilization through the inherent wavelength-selective properties of the distributed Bragg reflectors. The DBRs are designed with specific periodic structures that automatically select and stabilize the emission wavelength without requiring external control mechanisms or additional stabilization components
3Manufacturing precision
If external mirrors and Bragg reflectors are used for cavity formation, then wavelength selectivity is improved, but device complexity increases
Solution Approach 1:
The patent combines the cavity mirror functions and wavelength-selective Bragg reflector functions into a single integrated structure. The distributed Bragg reflectors are formed directly within the laser diode chip layers, serving simultaneously as cavity mirrors and wavelength-selective filters, thereby eliminating the need for separate external optical components
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 provides a stable, narrow emission spectrum that maintains low Beam Parameter Product (BPP) even when power is increased, enabling high-power laser diodes for direct material processing without the need for external stabilization, reducing production costs and complexity.
Implementation Method 1
The cavity mirrors are formed by distributed Bragg reflectors (DBRs) with different spectral characteristics
Implementation Method 2
etched terminal facets and a passivation layer to reduce residual reflectivity
Data Source
Figure 1~2
AI summary
Laser-diode device comprising: - a substrate; - at least one first cladding layer placed on the substrate; - an active layer placed on the first cladding layer and arranged to emit a radiation; - at least one second cladding layer placed on the active layer, said cladding layers being adapted to form a heterojunction, thereby allowing an efficient injection of current into the active layer and the optical confinement; - a first terminal facet and a second terminal facet placed transversally relative to the cladding layers and to the active layer, and formed within said layers by means of dry or wet etchings techniques and/or combinations thereof; - a periodic structure, placed in proximity to the second terminal facet and within the second cladding layer, and belonging to an optical cavity, wherein the first terminal facet represents the output mirror from which the radiation generated by the active layer exits, and the second terminal facet, integrated by the periodic structure, represents a second mirror having high reflectivity, so that the radiation produced by the active layer exits almost totally through the first mirror.