Compact External Cavity Laser Using Planar Lightwave Circuit
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Solution Overview
Problem
Existing external cavity lasers are either too large and power-consuming or sensitive to environmental variations, lacking a compact, low-noise, and cost-effective solution for applications requiring high stability and narrow linewidth.
Innovation Solution
A compact external cavity laser is developed using a planar lightwave circuit (PLC) with a gain chip butt-coupled to a waveguide featuring a planar Bragg grating, optimized for single polarization and low differential gain, and equipped with anti-reflection and high-reflection coatings, allowing thermal, electrical, or thermo-electrical tuning of the operating wavelength to reduce phase noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional bulk-optics-based external cavity lasers are used, then narrow linewidth and low phase noise are achieved, but the device size becomes prohibitively large
Solution Approach 1:
The patent replaces traditional bulk-optics mechanical components with integrated planar lightwave circuit technology, achieving the same optical functions (narrow linewidth, low phase noise) in a compact planar format that fits within standard semiconductor packages
Solution Approach 2:
The invention integrates multiple functional components (laser diode, Bragg grating, waveguide, isolator) into a single compact planar lightwave circuit module, nesting these elements together to achieve a small footprint while maintaining the external cavity laser's performance characteristics
2Area of stationary object
If semiconductor-based external cavity lasers are used, then smaller size and lower power consumption are achieved, but phase noise increases compared to bulk-optics solutions
Solution Approach 1:
The patent replaces conventional semiconductor laser cavities with a planar lightwave circuit implementation that uses integrated Bragg gratings and waveguides, achieving low phase noise performance comparable to bulk-optics systems while maintaining the compact size advantage of semiconductor devices
3Manufacturing precision
If fiber Bragg grating based external cavity lasers are used, then narrow linewidth is achieved, but sensitivity to vibrations increases and manufacturing cost increases
Solution Approach 1:
The patent replaces flexible fiber optic components with rigid planar lightwave circuit structures, eliminating vibration sensitivity while maintaining narrow linewidth performance through integrated Bragg gratings that are mechanically stable in standard semiconductor packages
Solution Approach 2:
The invention combines the laser diode, Bragg grating, and waveguide into a single integrated planar device, eliminating the separate fiber components that cause vibration sensitivity and reducing manufacturing complexity and cost
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 achieves a compact, low-power, high-stability external cavity laser with reduced phase noise and sensitivity to vibrations, offering improved reliability and frequency stability compared to traditional designs.
Implementation Method 1
The PLC device has a planar Bragg grating (PBG) integrated onto a rectangular waveguide
Implementation Method 2
The PLC device has anti-reflection coatings (ARC) on its input facet and output facet
Implementation Method 3
The gain chip has high-reflection coating (HRC) on a back facet
Implementation Method 4
The operating wavelength may be tuned thermally, electrically, or thermo-electrically
Data Source
AI summary
The present invention relates to external cavity laser (ECL) apparatuses and manufacturing processes, and more particularly to implementing low noise narrow bandwidth ECLs on planar lightwave circuit (PLC) platforms for harnessing high-performance, high-stability operation from a compact-footprint, low-power packaged device. An ECL device with narrow linewidth and low noise is disclosed, the device comprising a PLC device and a gain chip butt-coupled to each other. The PLC device has a planar Bragg grating (PBG) integrated onto a rectangular waveguide. The PLC device has anti-reflection coatings (ARC) on its input facet and output facet. The waveguide is designed to be selective of a single polarization. The gain chip has high-reflection coating (HRC) on a back facet and an ARC on a front facet. An operating wavelength of the ECL is aligned to a longer wavelength red slope of a reflectivity spectrum of the PBG. The operating wavelength may be tuned thermally, electrically, or thermo-electrically.