Array Laser Source Layout for Mode-Hop-Free Frequency Tuning
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Solution Overview
Problem
Current continuous frequency-tuning laser diodes face challenges in maintaining frequency stability and efficiency, particularly in applications requiring high power, narrow linewidth, and wide frequency-tuning ranges for optical coherent tomography, automatic optical inspection, and LiDAR, often experiencing mode hopping issues.
Innovation Solution
A continuous frequency-tuning array light source is designed with a substrate having distinct regions for gain, phase modulation, and internal reflection, featuring a core layer with gratings, air holes, and varying thicknesses of layers to enhance frequency tuning efficiency without mode hopping, incorporating a dielectric layer and electrodes for improved heat management and modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional laser diode structure is used for frequency tuning, then the device complexity is low, but mode hopping occurs and frequency stability deteriorates
Solution Approach 1:
The laser diode is divided into distinct functional regions: a gain region for light amplification, a phase modulation region for frequency control, and an internal reflection region with a grating structure for wavelength selection. This segmentation allows each region to be optimized independently, preventing mode hopping while maintaining manageable device complexity through specialized zone design.
Solution Approach 2:
Different regions of the laser diode are assigned different structural properties: the gain region has a specific core layer thickness for optimal amplification, the phase modulation region has a different thickness for frequency control, and the internal reflection region contains a grating structure. This local differentiation of structural quality enables continuous frequency tuning without mode hopping.
2Measurement precision
If the frequency-tuning range is expanded for precise distance resolution, then the measurement precision improves, but the power output decreases
Solution Approach 1:
The patent introduces a vertical dimension to frequency tuning by varying the core layer thickness across different regions (gain region, phase modulation region, internal reflection region). This dimensional approach enables continuous wavelength control over a wide range (1260-1290 nm) while maintaining high power output through optimized gain region design, achieving both precise distance resolution and high power simultaneously.
3Productivity
If a uniform core layer thickness is used throughout the laser diode, then the manufacturing precision is high, but the frequency tuning efficiency is low
Solution Approach 1:
The core layer thickness is made dynamic rather than static, varying continuously across different regions of the laser diode. The gain region has one thickness for optimal amplification, the phase modulation region has a different thickness for frequency control, and the internal reflection region has yet another thickness for wavelength selection. This dynamic thickness profile enables efficient continuous frequency tuning while remaining manufacturable through standard semiconductor fabrication techniques.
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 continuous frequency tuning of laser light without mode hopping, increasing tuning efficiency and resolution, as demonstrated by the wavelength variation range and change ratio graphs, achieving a frequency-tuning range of about 116 GHz with improved power output and precision.
Implementation Method 1
a core layer extending in the first direction on the substrate and including a grating in the internal reflection region
Implementation Method 2
a phase modulation region... electrodes on the dielectric layer and the ohmic contact layer
Implementation Method 3
the substrate may include air holes in the phase modulation region and the internal reflection region
Implementation Method 4
the core layer may include a quantum well layer in the gain region
Data Source
AI summary
Provided is a continuous frequency-tuning array light source. The light source may include a substrate including a gain region, a phase modulation region, and an internal reflection region arranged in a first direction, a core layer extending in the first direction on the substrate and including a grating in the internal reflection region, an upper clad layer on the core layer and the substrate, external reflection coating on one side wall of the substrate adjacent to the gain region, the core layer, and the upper clad layer, a dielectric layer on the upper clad layer in the phase modulation region and the internal reflection region, an ohmic contact layer on the upper clad layer in the gain region, and electrodes on the dielectric layer and the ohmic contact layer.