Integrated Optical Isolator Wedge Prism TOSA Design
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Solution Overview
Problem
Conventional optical transceivers in TOSAs are bulky and costly due to the use of multiple individual components for spot size conversion, isolation, and beam splitting, which complicates assembly and increases material costs, and results in extra light loss from complex waveguide structures.
Innovation Solution
An integrated and compact multifunctional optical isolator is developed, combining the functions of a splitter, isolator, and spot-size converter using a single wedge prism with a partially reflective coating and Faraday rotator, which refracts and rotates light to prevent back-reflection while optimizing beam size and polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple individual components (spot size converter, isolator, beam splitter) are used in TOSA, then each component can perform its specific function, but the device becomes bulky, costly, and complex to assemble
Solution Approach 1:
The patent combines the spot size converter, isolator, and beam splitter into a single integrated optical component. The device uses a single optical element with multiple functional zones: a first portion for spot size conversion, a second portion for isolation with Faraday rotator, and a third portion for beam splitting. This merging eliminates the need for multiple separate components and their associated mounts and alignment mechanisms.
Solution Approach 2:
The integrated optical component performs multiple functions simultaneously: it converts spot sizes to match laser output to fiber input, provides optical isolation to prevent back-reflection, and splits the beam for monitoring purposes. This multi-functional design replaces three specialized components with one universal element.
2Adaptability or versatility
If waveguide-based spot size converter is integrated with laser chip, then integration is achieved, but the waveguide structure becomes more complex with complicated fabrication process
Solution Approach 1:
The patent extracts the spot size conversion function from the laser chip integration and implements it as a separate optical component. Instead of modifying the laser chip with complex waveguides, the spot size conversion is performed by a dedicated optical element in the optical path, simplifying both the chip design and the overall fabrication process.
3Manufacturing precision
If waveguide-based spot size converter is used, then spot size conversion is achieved, but extra light loss occurs due to transmission mode mismatch
Solution Approach 1:
The patent uses a lens-based optical system to replicate the mode transformation function of complex waveguides. By using carefully designed lens combinations, the system achieves mode matching between laser output and fiber input without the transmission losses associated with waveguide interfaces and mode conversions.
4Manufacturing precision
If collimating/focusing lenses or anamorphic prisms are used for beam shaping, then spot size conversion is achieved, but the device becomes bulky
Solution Approach 1:
The patent merges the beam shaping optics into a compact integrated assembly. By combining the spot size conversion optics with the isolator and beam splitter in a single integrated component, the overall size is reduced compared to separate lens or prism assemblies while maintaining the beam shaping capability.
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 solution reduces the number of components, simplifies assembly, minimizes light loss, and achieves a compact, cost-effective design for TOSAs by integrating spot-size conversion, isolation, and beam splitting into a single unit, enhancing the aspect ratio of the laser beam and preventing back-reflection efficiently.
Implementation Method 1
a non-reciprocal rotator optically disposed between the first polarizer and the second polarizer for rotating the polarization of light transmitted therethrough
Implementation Method 2
a non-reciprocal rotator optically disposed between the input optics and the second polarizer for rotating the polarization of light transmitted therethrough
Implementation Method 3
the input optics include a wedge having a partially reflective coating disposed on a first face thereof, the partially reflective coating for reflecting a first portion of the input beam of light away from the wedge and allowing a second portion of the input beam of light to pass into the wedge
Data Source
AI summary
An integrated and compact multifunctional optical isolator (i.e., a combined splitter, isolator, and spot-size converter), which is suitable for use in a TOSA, includes input optics including a first polarizer, a Faraday rotator, and a second polarizer. The input optics include a wedge having a partially reflective coating disposed on a first face thereof. The input beam is incident on the first face at a non-normal angle of incidence such light passing through the wedge is refracted to a second face of the wedge, which is tilted relative to the first face by a predetermined wedge angle. At least one of the non-normal angle of incidence and the predetermined wedge angle is determined dependence upon a refractive index of the wedge material and a target anamorphic magnification of the input beam of light.