Optical Level Control Apparatus for GE-PON Surge Elimination
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Solution Overview
Problem
In Gigabit Ethernet Passive Optical Network (GE-PON) systems, the optical surge superposed on the head field of optical burst signals causes faults and deterioration in the Avalanche Photo Diode (APD) at the Optical Line Terminal (OLT), due to the gain-saturated state of optical fiber amplifiers when continuous light is inputted.
Innovation Solution
An optical level control apparatus that includes an input port, an output port, an optical device for amplifying or attenuating light, a detector for intensity measurement, and a control unit to eliminate the optical surge by controlling the optical device to output the optical burst signal only after a predetermined time period equal to or shorter than the laser ON time period, thus preventing the surge from affecting the OLT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If an optical fiber amplifier is provided midway of the optical fiber to enable long distance transmission, then transmission distance is improved, but optical surge is superposed on the head field of the optical burst signal causing faults and deterioration in the OLT
Solution Approach 1:
The harmful head field portion of the optical burst signal is extracted and removed by the optical level control apparatus before the signal reaches the OLT. The apparatus detects the head field and separates it from the useful signal portion, allowing only the clean burst signal to be transmitted to the receiver.
Solution Approach 2:
The optical level control apparatus performs preliminary processing of the optical burst signal by removing the head field before transmission to the OLT. This preventive action eliminates the optical surge problem before it can cause damage to the Avalanche Photo Diode in the OLT.
2Power
If the optical fiber amplifier operates in gain-saturated state with continuous light input, then amplification efficiency is improved, but optical surge is generated when light input ceases
Solution Approach 1:
The optical level control apparatus converts the harmful optical surge generated by the amplifier into a detectable signal characteristic. By detecting the presence and duration of the head field, the apparatus identifies the surge condition and removes only the necessary portion of the signal, transforming the harmful surge into a controllable parameter.
3Ease of manufacture
If optical burst signal is transmitted with TDMA technology, then system cost is reduced by using optical couplers, but optical surge cannot be eliminated
Solution Approach 1:
The optical level control apparatus serves as an intermediary device between the optical burst signal source and the OLT receiver. It mediates the signal transmission by detecting and removing the head field portion that causes optical surge, while allowing the useful signal to pass through to the receiver.
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 optical level control apparatus effectively eliminates the optical surge from the optical burst signal, preventing faults and deterioration in the OLT and enabling reliable long-distance transmission in GE-PON systems by ensuring the optical burst signal is processed without the adverse effects of the surge, thereby maintaining system integrity and performance.
Implementation Method 1
an optical device for amplifying or attenuating light
Implementation Method 2
a detector for intensity measurement
Data Source
AI summary
An optical level control apparatus includes an input port, an output port, an optical device to assume a state of outputting light inputted to the input port from the output port and a state of not outputting the light inputted to the input port from the output port; a detector to detect an intensity of the light inputted to the input port, and a control unit to detect an input of an optical burst signal to the input port on the basis of a result of detecting the intensity of the light and to control the optical device so that the signal, in which to eliminate a field extending up to an elapse of a period of first time equal to or shorter than laser ON time period of the signal from a head of the signal with its input being detected, is output from the output port.