Asymmetric DFB Laser Design for Enhanced Optical Efficiency
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Summary
Problems
DFB laser architectures in photonic integrated circuits (PICs) face issues such as symmetric output, which wastes light, and spatial hole burning (SHB), degrading performance over temperature and output power due to asymmetric photon and electric field distribution, making them less effective for optical systems.
Innovation solutions
A monolithic asymmetric DFB laser diode is developed with varying grating strengths along its length, using a higher grating strength at one end and a lower at the other, along with an apodized grating section to flatten photon density, reducing SHB effects and enhancing asymmetric output.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If a symmetric DFB laser architecture is used, then the laser structure is simple and manufacturable, but the output is symmetric causing light waste and reduced system efficiency
Why choose this principle:
The patent applies asymmetry by creating a DFB laser with non-uniform grating structure where the first grating section has a different grating strength than the second grating section. This asymmetric design causes the laser to emit light preferentially in one direction (asymmetric output), improving light output efficiency by directing more light toward the optical system coupling end while maintaining manufacturability through standard semiconductor fabrication processes.
Principle concept:
If a conventional DFB laser with uniform grating is used, then the device is simple to manufacture, but spatial hole burning degrades performance over temperature and output power
Why choose this principle:
The patent applies local quality by dividing the grating into multiple sections with different characteristics. The first grating section has a stronger grating strength to provide stable feedback in the gain region, while the second grating section has a weaker grating strength to reduce spatial hole burning effects. This localized differentiation improves performance stability over temperature and output power while remaining compatible with standard fabrication processes.
Application Domain
Data Source
AI summary:
A monolithic asymmetric DFB laser diode is developed with varying grating strengths along its length, using a higher grating strength at one end and a lower at the other, along with an apodized grating section to flatten photon density, reducing SHB effects and enhancing asymmetric output.
Abstract
Monolithic asymmetric optical waveguide grating resonators including an asymmetric resonant grating are disposed in a waveguide. A first grating strength is provided along a first grating length, and a second grating strength, higher than the first grating strength, is provided along a second grating length. In advantageous embodiments, the effective refractive index along first grating length is substantially matched to the effective refractive index along second grating length through proper design of waveguide and grating parameters. A well-matched effective index of refraction may permit the resonant grating to operate in a highly asymmetric single longitudinal mode (SLM). In further embodiments, an asymmetric monolithic DFB laser diode includes front and back grating sections having waveguide and grating parameters for highly asymmetric operation.