Optical Module WDM Filter Tilt Angle Optimization
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Solution Overview
Problem
Bidirectional optical modules face challenges in achieving high light coupling efficiency and reception sensitivity due to filter losses and optical crosstalk when using beam splitters for wavelength separation, especially with narrow wavelength differences between transmission and reception signals.
Innovation Solution
The optical module incorporates a wavelength division multiplexing (WDM) filter with a tilt angle of less than 20 degrees, a parallel light lens system, and an isolator to enhance light coupling and reduce crosstalk, converting light into parallel beams for uniform transmittance properties and improved signal separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a beam splitter is used to separate transmission and reception wavelengths, then wavelength separation is achieved, but light coupling efficiency deteriorates due to 3 dB filter loss
Solution Approach 1:
The patent changes the tilt angle parameter of the optical filter from the conventional 45 degrees to a smaller angle (10-30 degrees). This parameter change allows the filter to achieve adequate wavelength separation while reducing the polarization mode dispersion and associated light loss, thereby improving light coupling efficiency without sacrificing wavelength separation performance.
2Reliability
If a beam splitter is used for wavelength separation, then transmission and reception signals are separated, but reception sensitivity deteriorates due to filter loss
Solution Approach 1:
By optimizing the optical filter tilt angle to a smaller range (10-30 degrees) rather than the conventional 45 degrees, the patent reduces the polarization mode dispersion induced loss. This parameter optimization ensures that sufficient light reaches the photo diode while maintaining effective wavelength separation, thereby improving reception sensitivity.
3Ease of operation
If a 45-degree optical filter is used for signal separation, then transmission and reception signals are divided, but optical crosstalk increases when wavelength separation is narrow
Solution Approach 1:
The patent changes the tilt angle parameter from the fixed 45 degrees to an optimized range (10-30 degrees). This parameter change improves the filter's wavelength selectivity, enabling adequate signal separation even when the wavelength difference between transmission and reception signals is small (several nanometers), thereby reducing optical crosstalk.
4Productivity
If wavelength separation between transmission and reception signals is several nanometers, then narrow band transmission is achieved, but wavelength separation becomes difficult using conventional optical filters
Solution Approach 1:
The patent optimizes the optical filter tilt angle to a smaller range (10-30 degrees) which enhances the filter's wavelength resolution. This parameter change enables effective wavelength separation even when the separation between transmission and reception wavelengths is narrow (several nanometers), thereby maintaining high transmission efficiency while achieving reliable signal separation.
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 increases light coupling efficiency, enhances reception sensitivity, and reduces optical crosstalk, enabling effective long-distance transmission with improved communication quality.
Implementation Method 1
a first optical filter disposed between the optical transmitter and the holder to transmit the first optical signal and reflect the second optical signal
Implementation Method 2
a first parallel light lens disposed between the first optical filter and the optical transmitter, and a second parallel light lens disposed between the first optical filter and the holder
Implementation Method 3
an isolator disposed between the first parallel light lens and the optical transmitter
Data Source
AI summary
Disclosed is an optical module including an optical transmitter which is configured to output a first optical signal, an optical receiver which is configured to receive a second optical signal, a holder which is configured to include an optical fiber on which the first optical signal is incident and from which the second optical signal is emitted. The optical module further includes a first optical filter disposed between the optical transmitter and the holder to transmit the first optical signal and reflect the second optical signal, a first parallel light lens disposed between the first optical filter and the optical transmitter, and a second parallel light lens disposed between the first optical filter and the holder.