Monolithic Dual-Laser Injection Locking for Bandwidth
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Solution Overview
Problem
Conventional directly modulated semiconductor lasers suffer from high distortion near resonance frequency, limiting their bandwidth and modulation response, which is addressed by optical injection locking (OIL) but requires complex and temperature-sensitive discrete components that are difficult to implement effectively.
Innovation Solution
A semiconductor light-emitting device with monolithically integrated first and second laser sections on a common substrate, allowing for optical feedback and independent tuning of resonance frequency through phase sections and distributed Bragg reflector structures, enabling mutual injection locking and increased bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If optical injection locking is used to increase bandwidth and reduce distortion, then modulation response is improved, but device complexity increases due to requirement of discrete master and slave lasers with optical isolation components
Solution Approach 1:
The patent merges the master laser and slave laser into a single monolithically integrated laser device with two coupled laser sections. This integration eliminates the need for separate discrete lasers and external optical isolation components (such as optical isolators and circulators), thereby reducing device complexity while maintaining the optical injection locking mechanism for improved modulation bandwidth and reduced distortion.
Solution Approach 2:
The patent introduces a shared distributed Bragg reflector (DBR) structure as an intermediary element that couples the two laser sections optically. This shared DBR serves as the injection locking mechanism between the master and slave sections, replacing the need for external optical isolation components and simplifying the overall device architecture while enabling the desired modulation performance.
2Adaptability or versatility
If discrete components are used for optical injection locking, then frequency detuning control is possible, but temperature sensitivity and implementation difficulty increase
Solution Approach 1:
By integrating both laser sections and the frequency detuning control mechanism onto a single monolithic substrate, the patent eliminates the temperature sensitivity associated with discrete components and external optical paths. The unified structure ensures thermal equilibrium between the master and slave sections, stabilizing the frequency detuning control against temperature variations.
Solution Approach 2:
The patent implements independent phase control sections in both laser sections that allow electronic tuning of the optical frequencies. This parameter control mechanism enables precise frequency detuning adjustment while maintaining stability, as the control is integrated into the laser structure itself rather than relying on external discrete components susceptible to temperature drift.
3Object-generated harmful factors
If laser resonance frequency is set to exceed highest desired RF frequency, then distortion near resonance is reduced, but bandwidth is limited by relaxation resonance frequency
Solution Approach 1:
The patent employs optical feedback through the shared distributed Bragg reflector, where the slave laser section receives feedback from the master laser section. This feedback mechanism enables optical injection locking that increases the effective relaxation resonance frequency, thereby expanding the bandwidth while maintaining the ability to operate at resonance frequencies that exceed the highest desired RF frequency, thus reducing nonlinear distortion.
Solution Approach 2:
By combining two laser sections with a shared DBR into a monolithically integrated device, the patent creates a system where the master section operates at a frequency that exceeds the highest desired RF frequency (reducing distortion) while the coupled slave section, through optical feedback, extends the effective bandwidth beyond what a single directly modulated laser could achieve.
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 achieves a significantly increased resonance frequency and bandwidth, reducing nonlinear distortion and frequency chirp, while simplifying the implementation by integrating components on a single chip, enhancing mechanical robustness and compatibility with photonic integrated circuits.
Implementation Method 1
Each laser section has a phase section, a gain section and at least one distributed Bragg reflector (DBR) structure
Implementation Method 2
The first laser section and the second laser section are optically coupled to permit optical feedback therebetween
Data Source
AI summary
Semiconductor light-emitting devices; methods of forming semi-conductor light emitting devices, and methods of operating semi-conductor light emitting devices are provided. A semiconductor light-emitting device includes a first laser section monolithically integrated with a second laser section on a common substrate. Each laser section has a phase section, a gain section and at least one distributed Bragg reflector (DBR) structure. The first laser section and the second laser section are optically coupled to permit optical feedback therebetween. Each phase section is configured to independently tune a respective one of the first laser section and second laser section relative to each other.