Optical Fiber Amplifier Intermediate Stage Switching
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Solution Overview
Problem
Conventional optical fiber lasers and amplifiers face challenges in achieving fast rise and fall times due to difficulties in coordinating the switching of pump diodes across multiple amplification stages, leading to insufficient amplification speed and unacceptable leakage power when in an 'off' state.
Innovation Solution
An optical fiber amplifying system with an intermediate active optical fiber that acts as an optical switch, allowing the final pump sources to switch between low and high power states to control the system's output, while maintaining the optical source at a high power state to minimize leakage power and optimize amplification speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple amplification stages are used to achieve high power output, then the power output is improved, but the rise and fall times deteriorate due to coordination difficulties in switching pump diodes
Solution Approach 1:
The system segments the amplification function into two distinct stages: an intermediate amplification stage and a final amplification stage. Each stage has its own pump diodes and active optical fiber, allowing independent optimization of switching control for fast rise/fall times while maintaining high power output through cascaded amplification.
Solution Approach 2:
The intermediate amplification stage performs preliminary amplification of the optical signal before it reaches the final amplification stage. This preliminary action reduces the burden on the final stage's pump diodes to switch rapidly, as the signal is already amplified to a higher power level entering the final stage, thereby improving overall rise and fall times.
2Speed
If pump diodes are switched off rapidly to improve fall time, then the fall time is improved, but leakage power increases in previous amplification stages
Solution Approach 1:
The segmentation of amplification stages allows the final stage to be switched off rapidly for fast fall time, while the intermediate stage remains active at a reduced power level, preventing leakage power issues that would occur if all stages were switched off simultaneously.
Solution Approach 2:
The system dynamically adjusts the operating state of different amplification stages independently. The final stage can be rapidly switched between on and off states for fast modulation, while the intermediate stage maintains a dynamic equilibrium state that prevents excessive leakage power without requiring rapid switching.
3Speed
If simmer current is used in pump diodes during off state to improve rise/fall time, then the rise and fall times are improved, but the system complexity increases due to coordinated switching algorithms
Solution Approach 1:
By segmenting the control of pump diodes into stage-specific control circuits, the system simplifies the switching coordination problem. Each stage's pump diodes are controlled independently based on simple on/off or simmer current logic, avoiding the need for complex algorithms to coordinate switching across all stages simultaneously.
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 system achieves low leakage power and fast rise/fall times by using the intermediate active optical fiber as a switch, allowing for precise control of the amplification process without the need to switch off earlier stages, resulting in efficient amplification with reduced leakage.
Implementation Method 1
the optical radiation is substantially absorbed by the intermediate active optical fiber when the one or more final optical pump sources are together in a low power state
Implementation Method 2
one or more final optical pump sources together operatively coupled to the final active optical fiber and the intermediate active optical fiber and configured to output radiation of the first pump wavelength
Data Source
Figure 1
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Figure 3~4
AI summary
The present disclosure relates to methods and apparatuses for providing optical radiation having improved rise/fall times and improved levels of leakage. One method for amplifying optical radiation includes an intermediate stage (220) having an intermediate active optical fiber (222), the intermediate active optical fiber and a final amplifying stage (230) including a final active optical fiber (232), and providing optical radiation to the input of the intermediate active optical fiber, wherein one or more final optical pump sources (235) are together in a low power state such that the optical radiation is substantially absorbed by the intermediate active optical fiber and such that substantially no optical radiation of the amplified wavelength is transmitted by the intermediate stage. The intermediate active optical fiber (222) can then be switched to a transmissive state by switching the final optical pump source(s) (235) to a high power state. The input to the intermediate stage may comprise a seed laser (205) and plural first amplifier stages (210) having each a first active optical fiber (212). A filter (260) between the intermediate stage (220) and the final amplifying stage (230) prevents ASE and pump light from the intermediate stage to reach the final amplifying stage.