Single-Wavelength Bi-Directional Optical Transceiver Crosstalk Reduction

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Solution Overview

Problem

Single wavelength bi-directional optical transceivers experience optical crosstalk issues due to signal reflection, leading to poor signal sensitivity in communication systems, where 50% of the optical signal is reflected back into the receiver, affecting forward signals.

Innovation Solution

The implementation of a single wavelength bi-directional optical transceiver design that includes an isolator, an optical filter, and an absorber or AR coating to minimize signal reflection, with adjusted incidence and tilt angles to prevent optical crosstalk by ensuring the optical transmit signal is obliquely incident into the optical fiber and using an absorber to redirect reflected signals away from the receiver.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a 50:50 optical filter is used to separate signals in single wavelength bi-directional transmission, then the system can transmit data through the same optical fiber with easy installation and low maintenance costs, but 50% of the optical signal is reflected back into the receiver causing optical crosstalk and poor signal sensitivity

Engineering Contradiction:

Improveease of installationVSAvoidoptical crosstalk

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

An optical isolator is introduced as an intermediary component between the transmitter and optical filter. The isolator allows optical signals to pass through in the forward direction while blocking reflected signals from reaching the receiver, thereby eliminating optical crosstalk without affecting the ease of installation or data transmission capability of the single wavelength bi-directional system

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The optical isolator converts the harmful reflected signals into a beneficial effect by blocking them from reaching the receiver. The isolator utilizes the reflected light from the optical filter and directs it away from the receiver through its isolating property, transforming the potential crosstalk problem into a signal protection mechanism

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Ease of manufacture

If the optical transmit signal is directly coupled to the optical fiber, then the signal transmission is straightforward, but signal reflection occurs at the fiber interface causing optical crosstalk

Engineering Contradiction:

Improvesignal coupling simplicityVSAvoidsignal reflection

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The optical fiber is tilted at a specific angle (e.g., 7 degrees) relative to the optical axis, changing the geometric parameter of signal coupling. This angular adjustment ensures that reflected signals are directed away from the receiver while maintaining efficient forward signal transmission, thereby reducing optical crosstalk without complicating the manufacturing process

Inventive Principle:

Principle #35Parameter changes

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 design effectively reduces optical crosstalk, enhancing signal sensitivity by minimizing signal reflection and ensuring that the optical receive signal is vertically incident, thereby improving communication system performance.

Implementation Method 1

an optical filter reflecting some of the optical transmit signal and transmitting the remainder of the optical transmit signal

Methodology Applied

Scientific EffectOptical reflection: Reflection

Implementation Method 2

an optical filter reflecting some of the optical transmit signal and transmitting the remainder of the optical transmit signal

Methodology Applied

Scientific EffectOptical transmission: Refraction

Implementation Method 3

using an absorber to redirect reflected signals away from the receiver

Methodology Applied

Scientific EffectOptical absorption: Absorption (EM radiation)

Implementation Method 4

with adjusted incidence and tilt angles to prevent optical crosstalk by ensuring the optical transmit signal is obliquely incident into the optical fiber and using an absorber to redirect reflected signals away from the receiver

Methodology Applied

Scientific EffectAnti-reflective coating: Anti-Reflective Coating

Data Source

PatentUS8550726B2Optical transceiver using single-wavelength communication

Publication Date: 2013.10.08 OPTO ELECTRONICS SOLUTIONS CO LTD

AI summary

Disclosed herein is a single wavelength bi-directional optical transceiver for transmitting/receiving optical signals having the same wavelength through an optical communication system. The optical transceiver includes a transmitter including an isolator and converting an external input signal into an optical transmit signal, an optical filter reflecting some of the optical transmit signal and transmitting the other of the optical transmit signal, an optical fiber transmitting the optical transmit signal transmitted by the optical filter to a counterpart optical transceiver, a receiver receiving an optical receive signal from the counterpart optical transceiver via the optical fiber, and a body enclosing a portion of the transmitter, the optical filter, a portion of the optical fiber and a portion of the receiver. An incidence angle (θ2) formed between a central axis of the transmitter and a central axis of the optical fiber is adjusted to allow the optical transmit signal to be obliquely incident into the optical fiber in order to reduce reflection of the optical transmit signal by the optical fiber without coupling with the optical fiber when the transmitter transmits the optical transmit signal to the optical fiber.