Semiconductor Laser Temperature Control for Green Laser Modules
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current green laser modules using second harmonic generation (SHG) face challenges in achieving low power consumption and high wall-plug efficiency due to thermal crosstalk and temperature-dependent wavelength mismatches between semiconductor lasers and SHG elements, leading to waveform distortions and degraded output characteristics.
Innovation Solution
A light emitting device with a semiconductor laser, a first heater for temperature control, a gain unit, a second heater for the gain unit, and a second harmonic generation element, along with a temperature monitor to adjust drive signals for the heaters to match oscillation wavelengths and compensate temperature changes, ensuring optimal wavelength alignment and reduced thermal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermoelectric cooler (TEC) is used for wavelength control, then the oscillation wavelength can be precisely controlled to match the QPM wavelength, but the power consumption increases to several watts
Solution Approach 1:
The patent changes the temperature control approach by replacing the TEC with simple heaters that provide thermal compensation. The heaters adjust the temperature of the semiconductor laser to compensate for wavelength drift caused by temperature changes, achieving wavelength control without the high power consumption of TEC devices.
Solution Approach 2:
The patent extracts and removes the TEC component from the system, eliminating the high power consumption source. Instead of using active cooling, the system relies on passive thermal management with heaters that only compensate for temperature drift when needed, significantly reducing overall power consumption.
2Power
If the drive current of the semiconductor laser is modulated to control output intensity, then the output intensity can be adjusted, but the oscillation wavelength drifts from the QPM wavelength
Solution Approach 1:
The patent implements a feedback control system where the temperature of the semiconductor laser is continuously monitored and adjusted using heaters. This feedback mechanism compensates for wavelength drift that occurs during intensity modulation, maintaining wavelength stability while allowing output intensity to be controlled through drive current modulation.
3Stability of the object's composition
If the MOPA structure with SOA is used to suppress wavelength fluctuation, then the oscillation wavelength stability is improved, but thermal crosstalk between the DFB laser and SOA causes waveform distortions
Solution Approach 1:
The patent segments the thermal management of the DFB laser and SOA by providing separate heater control for each component. This allows independent temperature adjustment of the DFB laser to optimize its wavelength stability without being affected by thermal crosstalk from the SOA, thereby preventing waveform distortions while maintaining wavelength stability.
4Reliability
If the detuning between oscillation wavelength and gain peak wavelength is optimized for high temperature operation, then the output characteristics are improved at high temperature, but the detuning becomes too large at low temperature causing Fabry-Perot modes to oscillate
Solution Approach 1:
The patent makes the temperature compensation dynamic by using heaters that can actively adjust the DFB laser temperature based on operating conditions. This dynamic adjustment allows the system to optimize the detuning for high-temperature operation while preventing excessive detuning at low temperatures, thereby maintaining reliable output characteristics across a wide temperature range and preventing Fabry-Perot mode oscillation.
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 solution effectively suppresses waveform distortions and maintains optimal output characteristics across varying environmental temperatures, improving wall-plug efficiency and reducing power consumption by precise temperature control of the semiconductor laser and gain unit.
Implementation Method 1
a first heater, which controls a temperature of the semiconductor laser, provided near the semiconductor laser
Implementation Method 2
a second heater, which controls a temperature of the gain unit, provided near the gain unit
Implementation Method 3
a second harmonic generation element, which converts the amplified beam outputted from the gain unit to a second harmonic light and outputs the second harmonic light
Data Source
AI summary
A light emitting device includes a semiconductor laser, which oscillates in a single longitudinal mode, formed above a semiconductor substrate, a first heater, which controls a temperature of the semiconductor laser, provided near the semiconductor laser, a gain unit, which amplifies a beam outputted from the semiconductor laser and outputs an amplified beam, formed above the semiconductor substrate, a second heater, which controls a temperature of the gain unit, provided near the gain unit, and a second harmonic generation element, which converts the amplified beam outputted from the gain unit to a second harmonic light and outputs the second harmonic light.