Optical Waveguide Mode Filtering for Low-Loss Bidirectional Transmission
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Solution Overview
Problem
Conventional optical devices face challenges in effectively removing higher-order modes generated by reflection in optical fibers, leading to increased waveguide length and coupling loss, which hinders long-distance and high-bit-rate transmissions.
Innovation Solution
Incorporation of a mode filter within the optical waveguide circuit that utilizes a wavelength combiner and splitter to separate and remove higher-order modes, while minimizing coupling loss by guiding received light through a curved or rib waveguide structure, thereby improving reception sensitivity and reducing optical loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the waveguide length is decreased to extend transmission distance, then transmission distance is improved, but coupling loss increases due to higher-order mode generation
Solution Approach 1:
The patent extracts and removes the harmful higher-order modes from the optical signal using a mode filter. The mode filter selectively filters out higher-order modes while allowing fundamental modes to pass, thereby reducing coupling loss without requiring increased waveguide length
Solution Approach 2:
The patent introduces a wavelength combiner and splitter as an intermediary component between the optical transmitter and the optical fiber. This intermediary device converts higher-order modes to fundamental modes before transmission, reducing coupling loss while maintaining short waveguide length
2Device complexity
If the waveguide length is decreased to reduce device size, then device complexity is reduced, but reception sensitivity deteriorates due to increased coupling loss
Solution Approach 1:
The mode filter extracts and removes higher-order modes that cause coupling loss, thereby maintaining reception sensitivity even with reduced waveguide length and smaller device size
Solution Approach 2:
The wavelength combiner and splitter act as intermediaries to convert higher-order modes to fundamental modes, preserving signal quality and reception sensitivity in compact device configurations
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 a compact, low-loss single-fiber bidirectional optical device capable of long-distance and high-bit-rate transmissions by effectively removing higher-order modes, enhancing reception sensitivity and reducing overall optical loss.
Implementation Method 1
a mode filter that removes a higher-order mode of the received light by use of the wavelength combiner and splitter and includes a third port that outputs the received light having the higher-order mode removed from the received light
Implementation Method 2
The wavelength filter 132 is arranged in the optical waveguide 131, transmits the transmitted light from the optical input port 131A therethrough, outputs the transmitted light that has been transmitted therethrough, to the transmission line port 131C, and reflects the received light from the transmission line port 131C to the optical output port 131B
Implementation Method 3
The preamplifier 122 is an optical amplifier that optically amplifies the received light condensed by the condenser lens 121
Implementation Method 4
The condenser lens 112 is a lens that condenses the transmitted light from the light emitting element 111
Data Source
AI summary
An optical device has a waveguide circuit, a transmitter that transmits transmitted light to the waveguide circuit, and a receiver that receives received light from the waveguide circuit. The waveguide circuit has an optical waveguide, a wavelength combiner and splitter, and a mode filter. The optical waveguide includes a first port where the transmitted light output from the transmitter is input to and a second port where the transmitted light is output from, guides the transmitted light, and guides the received light input from the second port. The wavelength combiner and splitter is arranged in the optical waveguide between the first port and the second port. The mode filter removes a higher-order mode of the received light input by use of the wavelength combiner and splitter and includes a third port that outputs the received light having the higher-order mode removed from the received light, to the receiver.