Coherent Receiver Assembly Using Polarization Beam Splitter
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Solution Overview
Problem
The existing assembly methods for coherent receivers become complicated and costly when the wavelength range is extended, as they require a testing device with a tunable light source that can cover the new range, necessitating either extension or replacement of the light source, and the optical components need exclusive design for each band, leading to increased production complexity and costs.
Innovation Solution
The assembly method includes a polarization beam splitter with two wave ranges, one for the signal light beam and another out of this range, allowing the use of a test light beam from the second wave range to adjust the optical axes of optical components, eliminating the need for wavelength tunable light sources and enabling adjustment of components for both C-band and L-band using a common wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the wavelength range is extended to cover both C-band and L-band, then the adaptability of the coherent receiver is improved, but the device complexity increases due to requiring wavelength tunable light sources and exclusive design for each band
Solution Approach 1:
The patent makes the test light source universal by enabling it to operate at a common wavelength (1550 nm) that works for both C-band and L-band coherent receivers. The polarization beam splitter is designed with wide spectral coverage to handle both bands, eliminating the need for separate testing equipment for different wavelength ranges and simplifying the assembly process across multiple product variants.
Solution Approach 2:
The patent changes the operating parameter of the test light source from requiring wavelength tuning to using a fixed common wavelength (1550 nm). By adjusting the polarization state and using a polarization beam splitter with wide spectral coverage, the system achieves adaptability to different bands without changing the light source wavelength, thereby reducing complexity.
2Adaptability or versatility
If the polarization beam splitter is designed with wide spectral coverage to include both C-band and L-band, then the adaptability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates preliminary alignment features directly into the polarization beam splitter component, such as pre-positioned alignment marks and mechanical guides. These features enable operators to perform optical axis alignment more easily during assembly, reducing the actual precision required during the final adjustment stage while maintaining wide spectral coverage.
3Ease of operation
If a test light beam from the second wave range is used for adjustment, then the ease of operation is improved by eliminating wavelength tuning, but the measurement precision may be affected by the wavelength difference
Solution Approach 1:
The patent introduces the polarization beam splitter as an intermediary element that mediates between the test light beam at a common wavelength and the signal light beams at different wavelengths (C-band and L-band). The polarization beam splitter's wide spectral coverage ensures that alignment performed with the test light beam translates accurately to the actual operating wavelengths, maintaining measurement precision while simplifying operation.
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 approach reduces the complexity and cost of assembly by allowing the use of a common wavelength for adjusting optical axes across both C-band and L-band, narrowing the required tunable range of the test light source and simplifying production processes.
Implementation Method 1
a polarization beam splitter configured to divide the signal light beam into one of the polarized components and another of the polarized components
Implementation Method 2
inputting a test light beam included in the second wave range that is different from the wavelength range of the signal light beam from the signal light beam input port to the polarization beam splitter; and adjusting an optical axis of the at least one optical component based on the light intensity of the test light beam inputted to the signal receiving unit
Data Source
AI summary
A coherent receiver comprising: a signal port receiving the signal light that has two polarization components at right angles each other; a polarization dependent beam splitter (PBS) that splits the signal light into two portions depending on the polarizations contained in the signal light; a beam splitter (BS) that splits the local light into two portions; a multi-mode interference (MMI) device that interferes between one of the two portions of the signal light and one of the two portions of the local light; optical components provided between the PBS and the MMI device; and wherein the PBS splitting a first wavelength range of the signal light and a second wavelength range outside the first wavelength range.