Wavelength Locker Using Single Pilot Tone for DWDM Transmitters
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Solution Overview
Problem
Conventional wavelength division multiplexing (WDM) systems face challenges in efficiently and cost-effectively locking wavelengths of semiconductor lasers due to manufacturing variations, thermal changes, and spectral differences among individual transmitters, leading to complexity and increased costs with traditional wavelength locking methods.
Innovation Solution
An apparatus and method utilizing a single pilot tone and processor to detect amplitude and phase, calculating a quadrature term for wavelength locking, which determines the locking point based on the peak of the optical signal spectrum, minimizing the impact of spectral variations and thermal chirp, and allowing for centralized wavelength locking without the need for dedicated lockers for each transmitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wavelength locker is used for each laser in the array, then wavelength locking performance is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple wavelength locking functions into a single shared wavelength locker that serves multiple lasers in the array. This is achieved by time-division multiplexing the locking process, where the single locker sequentially locks each laser transmitter in turn, eliminating the need for dedicated lockers for each laser while maintaining locking performance for all transmitters.
Solution Approach 2:
The single wavelength locker is designed to perform multiple functions by locking different laser transmitters at different times. The locker is configured to accept multiple laser inputs and sequentially stabilize their wavelengths, making it a universal locking device that replaces multiple dedicated lockers while reducing overall system complexity.
2Reliability
If individual wavelength locking is implemented for each transmitter, then signal integrity is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges multiple wavelength locking operations into a single shared locker system, reducing the total number of components required. By time-division multiplexing the locking function across multiple lasers, the system achieves signal integrity through centralized control while lowering manufacturing costs due to reduced component count and simplified architecture.
3Stability of the object's composition
If conventional wavelength locking methods are used, then wavelength stability is achieved, but system complexity increases with number of transmitters
Solution Approach 1:
The patent implements periodic action by sequentially cycling through different laser transmitters in a time-division multiplexed manner. The single wavelength locker periodically switches between locking different lasers in a repeating cycle, allowing all transmitters to be stabilized using one locker while distributing the complexity over time rather than requiring simultaneous handling of all lasers.
Data Source
AI summary
An apparatus comprising a plurality of optical transmitters coupled to a fiber, a signal generator coupled to the optical transmitters and configured to provide a single pilot tone to the optical transmitters, and a processor positioned within a feedback loop between the fiber and the optical transmitters, the processor configured to adjust a wavelength for each of the optical transmitters to lock the wavelengths. An apparatus comprising at least one processor configured to implement a method comprising receiving an optical signal comprising a pilot tone, detecting an amplitude and a phase of the pilot tone, calculating a quadrature term using the amplitude and the phase, and wavelength locking the optical signal using the quadrature term.