Optical Transceiver Step-Wise Power Control for WDM Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In WDM systems, the transition of optical transceivers between ON and OFF states causes excessive or insufficient optical gain in amplifiers due to the slower time constant of the amplifier to adjust power, leading to signal level variations and noise or error rate issues, especially in long-reach systems.
Innovation Solution
An optical transceiver with a semiconductor laser diode, auto-power-controller circuit, and control unit that gradually varies output power in step-wise fashion based on a reference table, allowing synchronized adjustments with host controller commands to maintain target power levels, thereby synchronizing with the amplifier's gain adjustment time constants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the optical transceiver quickly transitions between ON and OFF states, then the response speed is improved, but the optical amplifier gain becomes excessive or insufficient during transition, causing signal level variations
Solution Approach 1:
The patent segments the power transition process into multiple discrete steps by using a reference table with multiple power levels. Instead of a single abrupt transition, the system progresses through intermediate power states (e.g., 100% -> 50% -> 25% -> 10% -> 0%), which allows the optical amplifier gain to adapt gradually between each step, preventing gain excess or deficiency while maintaining overall fast response.
Solution Approach 2:
The patent implements dynamic power adjustment by making the transition process adaptive rather than static. The control unit dynamically selects power levels from the reference table based on the current state and target state, allowing the transition path to change according to system conditions. This dynamic approach ensures the amplifier gain remains appropriate throughout the transition while maintaining speed.
2Reliability
If the optical amplifier adjusts gain quickly to match transceiver state changes, then the signal level stability is improved, but the amplifier response time is slower than the transceiver transition time
Solution Approach 1:
The patent applies preliminary action by having the transceiver reduce its output power to intermediate levels before fully transitioning to the OFF state. This preliminary power reduction creates a buffer period during which the amplifier can begin adjusting its gain in advance, rather than reacting after the transceiver has already completed its transition. The reference table provides pre-planned power levels that enable this anticipatory adjustment.
3Length of moving object
If multiple optical amplifiers are used in long-reach systems, then the transmission distance is improved, but the accumulation of optical level variations increases noise and error rates
Solution Approach 1:
The patent introduces an intermediary control mechanism in the form of a reference table with multiple power levels and a control unit that manages the transition process. This intermediary system coordinates the power adjustment between transceiver and amplifier, ensuring that each amplifier in the chain operates with appropriate gain settings during transitions. By controlling the transition through intermediate steps rather than abrupt changes, the intermediary mechanism prevents variations from accumulating across multiple amplifiers, thereby reducing noise and error rates in long-reach systems.
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 approach stabilizes optical signal levels across channels by matching the power adjustment rate with the amplifier's response, reducing noise and error rates, and is particularly effective in long-reach WDM systems by ensuring consistent power levels during transitions.
Implementation Method 1
The optical transceiver according to the present invention that communicates with a host controller comprises a semiconductor laser diode, an auto-power-controller circuit and a control unit. The laser diode outputs an optical signal.
Data Source
AI summary
The present invention provides an optical transmitter applicable to the WDM communication system. The optical transmitter includes a light-emitting device, an APC circuit and a processing unit. The processing unit, responding to a command TX_DISABL, which is sent from the control unit that communicates with the host controller, stops the optical output power of the transmitter by decreasing the reference to a preset value in step wise. Moreover, the processing unit, responding to a command ENABLE that is also sent from the control unit, starts the optical output by increasing the reference to another preset value in step wise.