Wideband Interferometer Polarization Beam Combiner
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Solution Overview
Problem
Conventional interferometer type polarization beam combiners and splitters are limited to a narrow wavelength range and are sensitive to manufacturing errors, which affects their performance in polarized light combining and splitting operations.
Innovation Solution
A wideband interferometer type polarization beam combiner and splitter is designed using a Mach-Zehnder interferometer with optical path length difference imparting units that generate differential birefringence and refractive index dispersion, allowing for equal rate of change of transmittance with wavelength, thereby suppressing wavelength dependency and expanding the operating wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional interferometer type polarization beam combiner and splitter is used with fixed optical path length difference, then polarization beam splitting can be achieved at a specific wavelength, but the operating wavelength range is limited to a narrow band
Solution Approach 1:
The patent applies parameter changes by making the optical path length difference variable rather than fixed. The optical path length difference is changed according to the wavelength of input light, allowing the device to maintain proper polarization beam splitting performance across a wide wavelength range. This is achieved by adjusting the optical path length difference to compensate for wavelength-dependent phase differences, thereby expanding the operating bandwidth while maintaining reliability.
2Ease of manufacture
If conventional interferometer design is used, then device structure is simple, but the device is highly sensitive to manufacturing errors in waveguide dimensions and birefringence
Solution Approach 1:
The patent applies dynamics by introducing a variable optical path length difference mechanism that can be adjusted after manufacturing. This dynamic adjustment capability allows compensation for manufacturing tolerances in waveguide dimensions and birefringence values. The system transitions from a static, fixed optical path design to a dynamic, adjustable one, enabling fine-tuning to achieve optimal performance despite variations in manufacturing precision.
3Measurement precision
If optical path length difference is set to achieve polarization splitting at center wavelength, then polarization extinction ratio is optimized at that wavelength, but wavelength dependency increases and performance degrades away from center wavelength
Solution Approach 1:
The patent applies parameter changes by making the optical path length difference a variable parameter that depends on the wavelength of input light. Instead of fixing the optical path length difference for a single center wavelength, the system adjusts this parameter across the wavelength range to maintain optimal polarization extinction ratio. This compensates for wavelength-dependent phase differences and reduces overall wavelength dependency, achieving both high polarization extinction ratio and wide wavelength independence.
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 enables high-performance polarization beam combining and splitting across a wide wavelength range with improved polarization extinction ratio and reduced wavelength dependency, effectively addressing the limitations of conventional devices.
Implementation Method 1
optical path length difference imparting units that generate differential birefringence
Implementation Method 2
interferometer type polarization beam combiner and splitter that splits, or combines, polarized light
Data Source
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AI summary
A interferometer type polarization beam combiner and splitter, which can combine or split polarized light over a wide band, is provided. The interferometer type polarization beam combiner and splitter includes: an optical splitter; an optical coupler; an optical path length difference imparting unit, which includes a plurality of optical waveguides arranged between the optical splitting unit and the optical coupling unit; one or two input/output ports connected to the optical splitter; and two input/output ports connected to the optical coupler. A half-integer of a wavelength of λc is set as a normalized phase difference, for the optical path length difference imparting unit, between two polarization states, and means for generating a difference in refractive index dispersion is provided between the optical waveguides of the optical path length difference imparting unit, so that the change rate of the transmittance with respect to wavelength is suppressed for the two polarization states.