Optical Burst Transmitter Scheduling for Wavelength Drift Control
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Solution Overview
Problem
Wavelength drift in optical transmitters during burst data transmission in optical communication networks, particularly in TWDM-PONs, is caused by thermal effects and rapid changes in burst allocation, leading to signal loss and crosstalk due to unstable wavelength emission.
Innovation Solution
Implementing a scheduling mechanism that gradually adjusts burst allocations over time to mitigate wavelength drift, using discrete or monotonically changing burst lengths to stabilize thermal equilibrium without additional hardware, assisted by heaters or heat pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If burst mode operation is used to transmit data in upstream TWDM-PONs, then data transmission efficiency is improved, but wavelength drift occurs due to thermal effects and current density changes
Solution Approach 1:
The patent applies preliminary action by implementing a warm-up period before actual data transmission. During this warm-up phase, the laser is activated with a reduced drive current or without data modulation, allowing the laser chip to reach thermal equilibrium before full-power data transmission begins. This preliminary thermal stabilization prevents wavelength drift during the actual data burst transmission.
Solution Approach 2:
The patent employs periodic action by implementing cyclic warm-up periods interspersed between data transmission bursts. The laser operates in alternating phases of warm-up (stabilization) and data transmission, creating a periodic operation pattern. This ensures that before each data burst, the laser has undergone sufficient warm-up to maintain wavelength stability, while still achieving high overall data transmission efficiency through the burst mode framework.
2Adaptability or versatility
If rapid changes in burst allocation are implemented to adapt to network demands, then network adaptability is improved, but wavelength drift increases due to thermal excursions
Solution Approach 1:
The patent applies preliminary action by implementing a warm-up period before actual data transmission. During this warm-up phase, the laser is activated with a reduced drive current or without data modulation, allowing the laser chip to reach thermal equilibrium before full-power data transmission begins. This preliminary thermal stabilization prevents wavelength drift during the actual data burst transmission.
Solution Approach 2:
The patent employs dynamics by making the warm-up period duration adaptive rather than fixed. The length of the warm-up period is dynamically adjusted based on network conditions, burst allocation requirements, and observed wavelength stability. This allows the system to maintain wavelength stability while adapting to varying network demands, as the warm-up duration can be extended when stability is critical or reduced when network throughput requirements are urgent.
3Stability of the object's composition
If thermoelectric coolers are used to stabilize wavelength, then wavelength stability is improved, but response time is too slow to counteract rapid thermal effects during bursts
Solution Approach 1:
The patent applies preliminary action by implementing a warm-up period before actual data transmission. During this warm-up phase, the laser is activated with a reduced drive current or without data modulation, allowing the laser chip to reach thermal equilibrium before full-power data transmission begins. This preliminary thermal stabilization prevents wavelength drift during the actual data burst transmission.
Solution Approach 2:
The patent employs periodic action by implementing cyclic warm-up periods interspersed between data transmission bursts. The laser operates in alternating phases of warm-up (stabilization) and data transmission, creating a periodic operation pattern. This ensures that before each data burst, the laser has undergone sufficient warm-up to maintain wavelength stability, while still achieving high overall data transmission efficiency through the burst mode framework.
4Stability of the object's composition
If counter-heating is implemented to maintain thermal equilibrium, then wavelength stability is improved, but device complexity increases due to additional heating elements
Solution Approach 1:
The patent applies self-service by utilizing the laser's own drive current structure to provide thermal management. During the warm-up period, the drive current is controlled to provide gentle heating that brings the laser to operational temperature. The same drive current circuitry that launches data bursts also serves the dual function of thermal management, eliminating the need for separate heating elements or counter-heating mechanisms.
Solution Approach 2:
The patent employs universality by making the drive current circuitry multi-functional. The same electrical circuit that modulates data onto the laser also controls the thermal state of the laser during warm-up periods. This eliminates the need for dedicated thermal management hardware, reducing device complexity while maintaining wavelength stability through intelligent control of the existing drive current.
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
Reduces wavelength drift and thermal excursions, preventing signal loss and crosstalk by stabilizing the optical frequency within channel filters, enhancing communication network performance.
Implementation Method 1
When the transmitter becomes active, i.e. during the burst-on time, a drive current with non-zero mean is applied to the transmitter laser, which emits data, drive current which in turn leads to heat dissipation on the internal resistance of the device. This results in heating of the laser chip by its own drive current, so-called self-heating, which continuously alters the optical emission frequency of the laser during the burst emission.
Implementation Method 2
a thermoelectric cooler or TEC is a standard element used to achieve tunability in DMLs to compensate for the wavelength drift
Data Source
Figure 1A
Figure 1B
Figure 1C~1E
AI summary
Example embodiments describe a device (1) comprising a scheduling means (100) configured to schedule an allocation (10) of bursts to drive an optical burst mode transmitter (2) in an optical communication network (3), wherein said scheduling means (100) is further configured to: - schedule a first allocation (11) of bursts for said optical burst mode transmitter (2); - schedule a second allocation (12) of bursts different from said first allocation (11) for said optical burst mode transmitter (2); and - gradually adjust said allocation (10) of bursts from said first allocation (11) to said second allocation (12) when said scheduling means (100) changes said allocation (10) of bursts from said first allocation (11) to said second allocation (12).