Pump Laser Phase Modulation for SBS Noise Suppression
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Solution Overview
Problem
Optical communication networks face challenges in suppressing signal noise on optical fibers, particularly due to limitations in stimulated Brillouin scattering (SBS) thresholds and pump amplitude fluctuations, which affect the reliability and capacity of data transmission.
Innovation Solution
A method and system that utilize a phase modulator to increase the SBS threshold of a pump laser from 15 dBm to 22 dBm, allowing the pump laser to operate at a higher power level and generate back scattering power, thereby limiting the output power signal and compensating for pump amplitude fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the pump laser power is increased to improve signal transmission, then the transmission capacity is improved, but stimulated Brillouin scattering (SBS) increases causing signal noise
Solution Approach 1:
The patent applies periodic phase modulation to the pump laser using a phase modulator, which periodically varies the phase of the pump laser at a specific frequency. This periodic action broadens the spectral width of the pump laser, thereby increasing the SBS threshold and allowing higher pump power to be transmitted without excessive SBS noise
Solution Approach 2:
The patent changes the physical parameters of the pump laser by modulating its phase, which transforms the narrow-linewidth pump laser into a broadened-linewidth signal. This parameter change increases the SBS threshold from typically around 5 dBm to above 22 dBm, enabling higher power operation
2Object-generated harmful factors
If phase modulation is applied to increase SBS threshold, then the SBS noise is suppressed, but pump amplitude fluctuation occurs
Solution Approach 1:
The patent employs a feedback mechanism where the phase-modulated pump laser signal is monitored and the output power is regulated. The system detects amplitude fluctuations caused by phase modulation and applies compensatory control to maintain stable output power, thereby suppressing SBS noise while maintaining pump amplitude stability
3Power
If the SBS threshold is increased to allow higher pump power, then the transmission capacity is improved, but the system complexity increases
Solution Approach 1:
The patent introduces a phase modulator as an intermediary device between the pump laser source and the optical fiber. This relatively simple component achieves the complex function of increasing SBS threshold through phase modulation, avoiding the need for more complex systems such as multi-wavelength laser arrays or sophisticated signal processing equipment
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 effectively suppresses SBS and stabilizes the output power signal, enhancing the reliability and capacity of optical communication networks by increasing the SBS threshold and managing pump amplitude fluctuations.
Implementation Method 1
modulating, by a phase modulator, a phase of the pump laser
Implementation Method 2
generating, at the pump laser, a back scattering power based on the power of the pump laser being greater than the increased SBS threshold
Data Source
AI summary
An optical system for suppressing signal noise on an optical fiber, including an input power signal; a pump laser configured to receive the input power signal; a phase modulator coupled to the pump laser configured to modulate, in response to the input power signal, a phase of the pump laser to increase a stimulated Brillouin scattering (SBS) threshold of the pump laser, wherein the pump laser is further configured to: increase a power at the pump laser to be greater than the SBS threshold; generate a back scattering power based on the power of the pump laser being greater than the increased SBS threshold; and limit an output power signal of the pump laser based on the generated back scattering power.