Burst-Mode Tunable EML Biasing for Wavelength Drift Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wavelength drift in burst-mode tunable EML transmitters causes channel crosstalk and increased Bit-Error-Rate due to self-heating effects during burst operations, which are not effectively managed by existing temperature control methods.
Innovation Solution
A method and circuit for biasing a tunable laser during burst-on and burst-off states, using differential bias currents and a laser driving circuit to maintain a consistent total current flow, minimizing thermal fluctuations and reducing wavelength drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If TEC control is used to maintain temperature, then wavelength stability is improved at static states, but self-heating effects during burst operations cause large wavelength drifts
Solution Approach 1:
The patent applies preliminary action by pre-heating the laser device before burst-mode operation using a heating current. This anticipates the self-heating effect that occurs during burst operations and compensates for it in advance, thereby maintaining wavelength stability despite temperature fluctuations during actual operation.
Solution Approach 2:
The patent changes the electrical parameters by applying different currents to different sections of the laser device. Specifically, it adjusts the injection current to the DBR section and the heating current to the heater section based on the operational state (burst-mode vs. non-burst-mode), thereby dynamically controlling the wavelength to compensate for temperature-induced drift.
2Productivity
If burst-mode operation is used to increase bandwidth, then system productivity is improved, but self-heating effects cause wavelength drift and channel crosstalk
Solution Approach 1:
The patent applies preliminary action by pre-heating the laser device before burst-mode operation using a heating current. This anticipates the self-heating effect that occurs during burst operations and compensates for it in advance, thereby maintaining wavelength stability despite temperature fluctuations during actual operation.
Solution Approach 2:
The patent changes the electrical parameters by applying different currents to different sections of the laser device. Specifically, it adjusts the injection current to the DBR section and the heating current to the heater section based on the operational state (burst-mode vs. non-burst-mode), thereby dynamically controlling the wavelength to compensate for temperature-induced drift.
3Productivity
If fast burst time is used to reduce overhead, then system productivity is improved, but wavelength drift increases due to insufficient thermal stabilization
Solution Approach 1:
The patent applies preliminary action by pre-heating the laser device before burst-mode operation using a heating current. This anticipates the self-heating effect that occurs during burst operations and compensates for it in advance, thereby maintaining wavelength stability despite temperature fluctuations during actual operation.
Solution Approach 2:
The patent changes the electrical parameters by applying different currents to different sections of the laser device. Specifically, it adjusts the injection current to the DBR section and the heating current to the heater section based on the operational state (burst-mode vs. non-burst-mode), thereby dynamically controlling the wavelength to compensate for temperature-induced drift.
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 solution effectively suppresses wavelength drift, ensuring stable transmission and reducing Bit-Error-Rate by maintaining consistent current flow through the laser, thus enhancing the performance of burst-mode operations.
Implementation Method 1
delivering, by the laser driving circuit, a second bias current to an anode of a phase-section diode disposed on a shared substrate of the tunable laser
Implementation Method 2
the self-heating effects, introduced by burst-operations, can cause large wavelength drifts
Implementation Method 3
temperature by Thermoelectric Cooling (TEC) control
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A method (700) of biasing a tunable laser (310) during burst-on and burst-off states includes receiving a burst mode signal (514) indicative of the burst-on state or the burst-off state, and when the burst mode signal is indicative of the burst-on state: delivering a first bias current (IGAIN) to an anode of a gain-section diode (590a) disposed on a shared substrate of the tunable laser; and delivering a second bias current (IPH) to an anode of a phase-section diode (590b) disposed on the shared substrate. The second bias current is less than the first bias current. When the burst mode signal transitions to be indicative of the burst-off state, the method also includes: delivering the first bias current to the anode of the gain-section diode; and delivering the second bias current to the anode of the phase-section diode, wherein the first bias current is less than the second bias current.