Optical Receiver Module Assembly with Small-Angle WDM Filtering
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Solution Overview
Problem
High-speed optical communication systems face challenges in maintaining wavelength selective function of wavelength division multiplexing (WDM) filters at larger incident angles, leading to reduced transmittance and signal mixing, while also struggling with optical coupling efficiency due to quasi-collimated beams and varying optical paths.
Innovation Solution
The process involves assembling an optical receiver module with a wavelength selective filter (WSF), a prism, and optical de-multiplexers (o-DeMuxes) on a carrier, where the WSF transmits and reflects wavelength multiplexed signals to stabilize the incident angle and ensure equal optical paths for de-multiplexing, enhancing wavelength discrimination and coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the incident angle of the WSF is increased to achieve wavelength division multiplexing, then the optical signals can be separated into different wavelengths, but the wavelength selective function degrades and transmittance decreases
Solution Approach 1:
The patent changes the incident angle parameter from the conventional large angle (45°) to a small angle (less than 20°, preferably less than 15°). This parameter change maintains the wavelength selective function while avoiding the degradation and transmittance loss that occur at larger incident angles. The small incident angle ensures that optical signals are properly separated without mixing between neighboring channels.
2Reliability
If the number of layers in the multi-layered filter is increased to maintain wavelength selective function at larger incident angles, then the wavelength discrimination improves, but the transmittance decreases
Solution Approach 1:
Instead of increasing the number of layers to compensate for large incident angle effects, the patent changes the fundamental parameter of incident angle itself. By operating at small incident angles (less than 20°), the system achieves wavelength selective function with the original layer configuration, avoiding the transmittance penalty that would result from adding more layers.
3Ease of manufacture
If the optical paths of de-multiplexed signals are made different to accommodate component layout, then the assembly becomes simpler, but the coupling efficiency at optical detectors varies and degrades
Solution Approach 1:
The patent creates equipotential optical paths by ensuring that all de-multiplexed optical signals travel equal distances from the WSF to their respective optical detectors. This is achieved by carefully positioning the optical detectors at equal optical path lengths, ensuring uniform coupling efficiency across all channels despite the different physical locations of the detectors.
4Area of stationary object
If an optical module implements multiple semiconductor optical devices within a single housing to save footprint, then the physical dimensions are reduced, but the complexity of maintaining wavelength selective function increases
Solution Approach 1:
The patent merges multiple semiconductor optical devices and their associated optical paths into a single integrated housing. The key to managing the complexity is the use of a WSF positioned at a small incident angle, which simplifies the optical path configuration and enables all devices to coexist in a compact arrangement without requiring complex alignment or isolation mechanisms.
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 maintains wavelength selective performance at smaller incident angles, reduces signal mixing, and improves coupling efficiency by stabilizing optical paths, effectively addressing the limitations of existing WDM systems.
Implementation Method 1
a wavelength selective filter (WSF) that divides eight (8) optical signals multiplexed in a wavelength multiplexed signal into two portions
Implementation Method 2
The prism includes a first surface and a second surface, where the first surface reflects the wavelength multiplexed signal toward the WSF
Implementation Method 3
The mirror reflects the first wavelength multiplexed signal transmitting through the WSF
Data Source
AI summary
A process of assembling an optical receiver module that receives a wavelength multiplexed signal is disclosed. The process includes a step of sequentially mounting a wavelength selective filter (WSF), a prism, a mirror, and first and second optical de-multiplexers (o-DeMuxes) each on the carrier. The WSF transmits a first wavelength multiplexed signal but reflects a second wavelength multiplexed signal. The prism includes first and second surfaces, where the first surface reflects the wavelength multiplexed signal toward the WSF, while the second surface receives a second wavelength multiplexed signal coming from the WSF. The mirror reflects the first wavelength multiplexed signal transmitting through the WSF. The first and second o-DeMuxes de-multiplex the first and second wavelength multiplexed signals.