Phase-Shifted External Cavity Laser for Compact Wavelength Tuning
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Solution Overview
Problem
Existing external cavity lasers require a relatively large area, making them less compact and potentially less efficient.
Innovation Solution
The improved external cavity laser incorporates a phase shifted Bragg grating (FBG) with a discontinuity that acts as both a reflector and a filter, enabling a compact design and simplified wavelength control through control of the discontinuity and cavity length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional external cavity laser designs are used, then the laser provides stable operation, but the device occupies a relatively large area
Solution Approach 1:
The patent merges the reflector and filter functions into a single phase-shifted Bragg grating structure. The Bragg grating simultaneously provides optical feedback (reflector function) and wavelength selection (filter function), eliminating the need for separate components and reducing the overall device area while maintaining stable laser operation
Solution Approach 2:
The phase-shifted Bragg grating serves multiple functions: it acts as a reflector to provide optical feedback to the cavity, a filter to select the laser wavelength, and a wavelength-tuning element through controlled phase shift. This multi-functionality reduces the number of components needed and compact the device
2Device complexity
If multiple separate components are used for reflection and filtering, then each component can be optimized independently, but the device complexity increases
Solution Approach 1:
The patent combines multiple optical functions (reflection, filtering, wavelength tuning) into a single integrated phase-shifted Bragg grating structure, reducing the number of discrete components and simplifying the overall device architecture while maintaining the ability to optimize performance through phase shift control
3Ease of operation
If conventional wavelength control methods are used, then wavelength tuning is possible, but the control operation becomes complex
Solution Approach 1:
The patent enables wavelength tuning by changing the phase shift parameter of the Bragg grating. By controlling the phase shift (e.g., through thermal or electro-optic effects), the laser wavelength can be tuned across a range, providing simple and direct wavelength control without complex mechanical adjustments
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
This configuration achieves a more efficient and compact external cavity laser with improved optical feedback and filtering, allowing for higher reflected and transmitted radiation power and simplified wavelength tuning.
Implementation Method 1
The phase shifted Bragg grating, FBG, serves both as a reflector for providing optical feedback to the cavity as well as a filter to transmit laser radiation with a narrow linewidth
Implementation Method 2
The heat generated near the discontinuity causes the length thereof to change. Therewith the wavelength for which a predetermined phase-shift (e.g. a phase shift π) is achieved between the forward and backward travelling waves can be tuned by appropriately heating the discontinuity
Data Source
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AI summary
An improved external cavity laser (1) is provided herein that comprises a gain section (2) and an external cavity passive chip (3) with a first end (31) that is optically coupled to the gain section (2) and with a second end (35) providing a laser output, the external cavity passive chip (3) having a cavity (33) between the first end (31) and a phase shifted Bragg grating, FBG (34).