Curved Waveguide Laser with Anamorphic Lens for Linear Output
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Solution Overview
Problem
Conventional semiconductor laser devices with longer cavities are susceptible to unwanted ripple in optical power versus current characteristics due to residual reflections and feedback from optical path reflectors, leading to sensitivity issues and suboptimal performance.
Innovation Solution
A semiconductor laser device design featuring a curved waveguide with a non-orthogonal front facet and an anamorphic fiber lens that minimizes feedback by directing optical radiation at an angle, combined with a wavelength-selective reflector within the optical fiber to form a laser cavity, ensuring stable wavelength locking and reduced gain ripple effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional semiconductor laser device with a longer cavity is used to produce high gain, then the output power is improved, but unwanted ripple appears in the optical power versus current characteristics due to residual reflections and feedback
Solution Approach 1:
The patent extracts and eliminates the harmful feedback path by removing the front facet reflector and replacing it with a curved waveguide structure. This extraction of the problematic reflection source allows high gain operation without the destabilizing feedback that causes ripple in the optical power characteristics.
Solution Approach 2:
The patent applies curvature to the waveguide structure, using a curved waveguide instead of a straight one. This curvature redirects the optical path so that reflections from the rear facet do not couple back into the waveguide, thereby eliminating the Fabry-Perot cavity effects that cause optical power ripple while maintaining high gain.
2Object-affected harmful factors
If a curved waveguide with tilt angle is used to suppress back reflections, then feedback is reduced, but the device complexity increases
Solution Approach 1:
The patent merges the functions of the waveguide and the reflector suppression mechanism into a single integrated structure. The curved waveguide simultaneously performs optical guidance and feedback suppression, eliminating the need for separate components and reducing overall device complexity despite the curved geometry.
Solution Approach 2:
The curved waveguide structure uses geometric curvature to redirect optical paths. By designing the waveguide with a specific radius of curvature, the patent achieves automatic suppression of back reflections without requiring additional optical elements, thereby managing complexity through elegant geometric design.
3Reliability
If a wavelength selective reflector is added to stabilize the laser wavelength, then wavelength locking is improved, but the device complexity increases
Solution Approach 1:
The patent employs the laser's own emitted light to create the wavelength selective feedback. By using the rear facet reflection and the curved waveguide geometry, the system self-regulates the wavelength without requiring external wavelength selective components, thereby achieving wavelength stability without increasing device complexity.
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 design achieves highly linear laser emission with suppressed gain ripple effects, enabling high output power and improved stability, particularly suitable for applications like erbium-doped fiber amplifiers.
Implementation Method 1
a wavelength-selective reflector arranged within the optical fiber to form a laser cavity between the rear facet and the wavelength-selective reflector
Implementation Method 2
an optical fiber waveguide with a fiber lens coupling radiation between the optical fiber and the front facet of the semiconductor waveguide
Implementation Method 3
a curved waveguide with a non-orthogonal front facet and an anamorphic fiber lens that minimizes feedback by directing optical radiation at an angle
Data Source
AI summary
A laser device having a semiconductor gain element (12) optically coupled to an optical fiber (14) by using an angled anamorphic fiber lens (28) and including a wavelength-selective front reflector (26). The laser device possesses improved output characteristics such as a highly linear laser emission output, even when the amplification section produces a high amount of gain. Such a laser source can also be used in various applications such as pump lasers for fiber amplifiers or frequency doubling systems. The semiconductor gain element (12) has a curved waveguide with the intracavity facet (18) and the inclined fiber lens tip (30) being substantially parallel to prevent wavelength and intensity instabilities of the external cavity LD.