Semiconductor Laser Assembly for Subpicosecond Pulse Generation
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Solution Overview
Problem
Current semiconductor laser devices face challenges in generating ultrashort pulse laser light with subpicosecond pulse widths due to chirping effects, which are difficult to mitigate using existing dispersion compensation methods.
Innovation Solution
A semiconductor laser apparatus assembly incorporating a mode-locked semiconductor laser device with a current injection type and an external resonator featuring a dispersion compensation optical system that introduces negative group velocity dispersion and provides spectral filtering, allowing for self-modulation and optimal group velocity dispersion to achieve subpicosecond pulse generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If passive mode locking is used in a semiconductor laser device, then pulse time width can be reduced to several picoseconds or less, but chirping effects prevent achieving subpicosecond pulse widths
Solution Approach 1:
A dispersion compensation optical system is introduced as an intermediary component between the semiconductor laser device and the output. This system includes a first dispersion compensation optical system with negative group velocity dispersion and a second dispersion compensation optical system with positive group velocity dispersion. The intermediary systems compensate for the chirping effects by introducing opposite dispersion, thereby enabling subpicosecond pulse width achievement while maintaining phase alignment stability.
Solution Approach 2:
The invention changes the dispersion parameter of the optical system by introducing compensation systems with specific group velocity dispersion values. The first dispersion compensation optical system provides negative group velocity dispersion to counteract positive chirping, while the second provides positive group velocity dispersion to counteract negative chirping. This parameter change enables the system to achieve subpicosecond pulse widths by balancing the dispersion effects.
2Duration of action of moving object
If dispersion compensation optical systems are introduced to reduce pulse time width, then subpicosecond pulses can be generated, but the device complexity increases
Solution Approach 1:
The dispersion compensation optical systems are designed to perform multiple functions: they compensate for chirping effects, enable subpicosecond pulse generation, and can be adjusted to handle different chirping conditions (positive and negative). The system's ability to address multiple dispersion scenarios with a unified approach reduces the need for multiple specialized components, thereby managing complexity while achieving the desired pulse width reduction.
3Duration of action of moving object
If mode locking method is used in semiconductor laser devices, then ultrashort pulse generation is achieved, but energy efficiency remains lower compared to other laser types
Solution Approach 1:
The semiconductor laser device utilizes self-phase modulation, a nonlinear optical effect inherent to the laser medium itself, to generate the mode-locked pulses. This self-service mechanism eliminates the need for external modulators or additional energy-intensive components, thereby improving energy efficiency while achieving ultrashort pulse generation. The laser medium's own nonlinear response is harnessed to create the necessary phase modulation for pulse formation.
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 reduces pulse time width to subpicosecond levels, enhances energy efficiency, and stabilizes the laser output, overcoming chirping issues and achieving reliable generation of ultrashort pulses.
Implementation Method 1
configured to generate self modulation
Implementation Method 2
a saturable absorber showing a nonlinear optical response is provided in the semiconductor laser device
Implementation Method 3
to introduce a negative group velocity dispersion into the external resonator
Implementation Method 4
chirping given to the light pulses according to the generation of the pulses
Implementation Method 5
to provide spectral filtering after the external resonator
Implementation Method 6
a carrier density in an active layer (gain portion) varies temporally according to the pulse generation
Implementation Method 7
a refractive index of the active layer varies
Data Source
AI summary
A semiconductor laser apparatus is provided. The semiconductor laser apparatus includes a mode-locked semiconductor laser device and an external resonator including a dispersion compensation system, wherein the semiconductor laser apparatus is configured to generate self modulation, to introduce a negative group velocity dispersion into the external resonator, and to provide spectral filtering after the external resonator.