Short Cavity DBR Laser Tuning Speed
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Solution Overview
Problem
Current DBR lasers face limitations in tuning speed due to material degradation from current injection and high power requirements, slow frequency response, and narrow tuning bands when using temperature tuning.
Innovation Solution
A DBR laser design with a short gain cavity and a DBR region having a kappa of at least 100 cm−1, tuned to operate on the long wavelength side of the Bragg peak using the detune loading effect, which enhances speed and reduces power consumption without degrading materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If current injection is used to tune the reflection peaks of the grating structures, then the tuning speed is improved, but the materials of the DBR section are degraded over time
Solution Approach 1:
The patent replaces the electrical current injection mechanism with a temperature-based tuning mechanism. By using temperature control to shift the Bragg peak wavelength, the system achieves tuning functionality without the material degradation caused by high current injection, thus resolving the contradiction between tuning speed and material durability.
Solution Approach 2:
The patent changes the tuning parameter from current to temperature. By controlling the temperature of the DBR section, the Bragg peak wavelength can be shifted to achieve frequency tuning without injecting high currents that would degrade the materials. This parameter substitution resolves the contradiction by maintaining tuning capability while improving reliability.
2Reliability
If temperature tuning is used to shift the reflection spectrum, then the material degradation is reduced, but the power requirements increase and frequency response slows down
Solution Approach 1:
The patent uses only a small portion of the DBR structure (a localized grating section) for temperature-based wavelength tuning, rather than heating the entire DBR structure. This partial action approach reduces the total power required for temperature tuning while still achieving the necessary Bragg peak shift, thus resolving the contradiction between reliability and power consumption.
3Reliability
If temperature tuning is used to shift the reflection spectrum, then the material degradation is reduced, but the frequency response becomes slow
Solution Approach 1:
The patent applies temperature tuning to only a localized portion of the DBR structure rather than the entire structure. This partial action reduces the thermal mass that needs to be heated, thereby improving the frequency response speed while maintaining the advantage of reduced material degradation compared to current injection.
4Reliability
If temperature tuning is used to shift the reflection spectrum, then the material degradation is reduced, but the tuning band becomes narrow
Solution Approach 1:
The patent segments the DBR structure into multiple sections with different grating characteristics. By temperature-tuning specific segments, the system can achieve broader overall tuning bandwidth while each individual segment operates within its optimal range, thus resolving the contradiction between reliability and tuning band width.
Solution Approach 2:
The patent employs a composite DBR structure combining multiple grating sections with different properties. This composite approach allows the system to achieve extended tuning bandwidth through coordinated temperature control of different segments, while each segment operates reliably within its designed parameters.
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 design achieves high-speed modulation bandwidth up to 25 GHz, low power consumption, and improved side mode suppression ratio, while maintaining the laser's material integrity and reducing power requirements.
Implementation Method 1
a distributed Bragg reflector (DBR) region having a grating with a kappa of at least about 100 cm−1
Implementation Method 2
a gain medium is in optical communication with one or more grating structures that define reflection peaks that control which wavelengths of light are reflected back into the gain section
Implementation Method 3
The lasing on long wavelength side of the Bragg peak can be obtained as a result from a detune loading effect
Implementation Method 4
a gain cavity having a length from about 10 microns to about 150 microns
Data Source
AI summary
A long wavelength, short cavity laser can include: an active region or gain cavity having a length from about 10 microns to about 150 microns; a gap region adjacent to the active region and having a gap length that is less than 30 microns or less than the length of the active region; and a distributed Bragg reflector (“DBR”) region having a grating with a kappa of at least about 200 cm−1, wherein the gap region is between the active region and the DBR region, and wherein the laser lases at a long wavelength side of a Bragg peak of the laser. The laser can have a second DBR region opposite of the first DBR region.