Semiconductor Laser External Resonator 45-Degree Mirror Alignment
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Solution Overview
Problem
Existing semiconductor lasers struggle to meet the high monochromaticity and wavelength stability requirements for applications like DWDM due to difficulties in precisely aligning the optical axes of the laser diode chip, lens, and reflection mirror, which affects the feedback of the laser beam and the control of its wavelength.
Innovation Solution
The semiconductor laser employs a 45° reflection mirror to change the optical axis direction of the laser beam from horizontal to vertical, allowing the lens to be positioned on the x-y plane instead of the x-z plane, which simplifies the alignment and fixing process, and integrates a wavelength-selective filter to control the beam's feedback and wavelength, enabling more precise control over the beam's characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the optical axis of the lens is aligned with the optical axis of the laser diode chip and reflection mirror, then the laser beam feedback is achieved, but the alignment precision is difficult to control and the manufacturing complexity increases
Solution Approach 1:
The patent changes the alignment dimension by tilting the reflection mirror at 45 degrees relative to the laser diode chip. Instead of aligning optical axes in the same plane (x-z plane), the mirror tilt redirects the beam path to a different spatial dimension, allowing the lens to be positioned on the x-y plane. This dimensional change simplifies alignment because the lens optical axis can now be perpendicular to the package bottom plane without requiring precise co-alignment with the laser diode chip optical axis.
Solution Approach 2:
The tilted reflection mirror acts as an intermediary element that decouples the alignment requirements between the laser diode chip and the lens. By introducing this intermediate component with a fixed 45-degree tilt, the patent mediates the optical path between the two components, allowing them to be aligned independently along different reference planes, thus reducing the overall manufacturing complexity.
2Ease of manufacture
If the lens is positioned on the x-z plane with coincident optical axes, then the beam feedback path is established, but the alignment process becomes complex and costly
Solution Approach 1:
The patent repositions the lens from the x-z plane to the x-y plane by tilting the reflection mirror. This moves the lens alignment reference from the longitudinal axis to a transverse plane, where the lens optical axis can be simply perpendicular to the package bottom. This dimensional relocation dramatically simplifies the alignment process and reduces manufacturing costs.
Solution Approach 2:
Instead of making the lens optical axis coincide with the laser diode chip optical axis (traditional approach), the patent inverts the approach by making the reflection mirror tilt at 45 degrees and the lens optical axis perpendicular to the package bottom. This inverted alignment strategy simplifies the manufacturing process while achieving the same functional result of beam feedback.
3Ease of manufacture
If a 45° reflection mirror is used to change the optical axis direction, then the lens can be positioned on the x-y plane simplifying alignment, but additional optical components are required
Solution Approach 1:
The tilted reflection mirror serves multiple functions: it redirects the beam path at 45 degrees, enables the lens to be positioned on the x-y plane, and facilitates the feedback of the laser beam to the laser diode chip. By making this single component multi-functional, the patent reduces the need for additional separate alignment mechanisms, thereby offsetting the added component with functional consolidation.
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 allows for stable and precise control of the laser beam's wavelength and monochromaticity, reducing the complexity and cost of manufacturing while improving the alignment precision, enabling the production of external resonator type lasers with enhanced performance.
Implementation Method 1
a 45° reflection mirror to change the optical axis direction of the laser beam from horizontal to vertical
Implementation Method 2
a lens for collimating the emitted laser beam into a parallel beam
Implementation Method 3
a wavelength-selective filter for reflecting part of the laser beam which is incident through the lens so that the laser beam is fed back to the laser diode chip
Data Source
AI summary
A semiconductor laser using an external resonator. A laser diode chip emits a laser beam in a horizontal direction parallel to the bottom plane of a package, and the travel path of the laser beam is changed into a vertical direction by a reflective mirror next to a laser beam-emitting surface of the laser diode chip. As a result, the beam arrangement of the external cavity is available on a plane parallel to the bottom plane of the package through a lens installed on the vertical travel path of the laser beam. Consequently, the beam is easily arranged. Furthermore, an additional reflective mirror is installed above the lens which changes the vertical travel path into a horizontal travel path, which allows the beam traveling parallel to the bottom plane to be easily arranged through the lens. The production of the package can also be enabled in the configuration where various optical tools are arranged on the bottom of the package. Therefore, the semiconductor laser using an external cavity and having various characteristics can be easily manufactured.