DBR Master Laser Injection-Locked Microring for 200 GHz Bandwidth
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Solution Overview
Problem
Current semiconductor lasers face limitations in achieving high modulation bandwidths beyond 100 GHz due to constraints in design, such as optical damage, excessive heating, and poor stability of materials, particularly in edge-emitting lasers and VCSELs, which hinder their application in high-speed optical communication systems.
Innovation Solution
A novel injection-locking scheme using a DBR master laser monolithically integrated with a whistle-geometry microring laser, combined with photon-lifetime modulation, to enhance resonance frequency and modulation bandwidth, overcoming the limitations of edge-emitting lasers and VCSELs by allowing strong optical injection and reducing low-frequency roll-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If increased injection currents are used to achieve higher photon density and shorter photon lifetime for enhanced modulation bandwidth, then the relaxation-oscillation frequency increases, but optical damage to laser facets and excessive heating occur
Solution Approach 1:
An external master laser serves as an intermediary to inject locked photons into the slave laser cavity, enabling modulation bandwidth enhancement without requiring increased injection currents that would cause optical damage and heating. The master laser acts as a mediator that transfers the modulation signal while avoiding the harmful effects of direct current modulation.
Solution Approach 2:
The patent replaces direct electrical current modulation (mechanical/electrical system) with optical injection locking (optical system). Instead of modulating the slave laser current directly, the modulation is achieved through optical injection from the master laser, substituting the electrical modulation mechanism with an optical one that avoids the associated heating and damage problems.
2Speed
If shorter laser cavities are used to achieve smaller photon lifetime for enhanced modulation bandwidth, then the relaxation-oscillation frequency increases, but higher injection current densities are required which limit the modulation bandwidth
Solution Approach 1:
The master laser serves as an intermediary that enables the slave laser to achieve high modulation bandwidth without requiring high injection current densities. The optical injection mechanism allows the slave laser to respond to modulation signals through photon injection rather than direct current modulation, circumventing the current density limitations.
3Speed
If Ti:LiNbO3 electro-optic modulators are used to achieve high modulation frequency and broadband performance, then the modulation bandwidth exceeds 70 GHz, but the half-wave voltage Vπ becomes excessively high exceeding 10 V
Solution Approach 1:
The patent merges the master laser and slave laser into a single injection-locked system where the slave laser inherits the modulation capabilities of the master laser. This combination allows the system to achieve high modulation bandwidth without requiring the high voltages needed by separate electro-optic modulators, as the optical injection mechanism provides efficient coupling between the modulation signal and the optical output.
4Speed
If polymer electro-optic modulators are used to achieve 145 GHz modulation bandwidth, then the modulation bandwidth is enhanced, but the technology remains immature with poor stability against temperature and optical power
Solution Approach 1:
The patent uses homogeneous semiconductor materials for both the master and slave lasers, ensuring consistent thermal and optical properties throughout the system. This material homogeneity provides stable operation against temperature and optical power variations, avoiding the stability problems associated with polymer materials that have heterogeneous properties and poor thermal stability.
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
This approach achieves a 3-dB modulation bandwidth of up to 200 GHz, providing a low-cost, ultrafast, and stable optical transmitter suitable for high-speed optical communication, addressing the limitations of existing technologies and enabling broadband applications.
Implementation Method 1
The photon-lifetime modulation for the light circulating in the WRL mode is implemented through an electroabsorption (EA) modulator monolithically integrated on the same semiconductor substrate
Implementation Method 2
A novel injection-locking scheme using a DBR master laser monolithically integrated with a whistle-geometry microring laser, combined with photon-lifetime modulation, to enhance resonance frequency and modulation bandwidth
Data Source
AI summary
The invention provides a semiconductor light-emitting device having a monolithically integrated master laser, such as a distributed-Bragg-reflector (DBR) master laser, and injection-locked ring slave laser with modulated photon lifetime for optical communication beyond 100 GHz.