Semiconductor laser device and method for manufacturing the same
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Solution Overview
Problem
Conventional uncooled type modulator-integrated semiconductor lasers require complicated electric wiring to switch modulated signals between electro-absorption modulators and suffer from unstable laser oscillation and deteriorating modulation waveforms due to temperature changes, especially at high speeds.
Innovation Solution
A semiconductor laser device with a monolithically integrated electro-absorption modulator and optical attenuator, controlled by a control unit that adjusts the DC bias voltage of the optical attenuator to compensate for temperature changes, maintaining consistent average light output without reducing the DC bias current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the DC bias current of the semiconductor laser is significantly reduced on the low temperature side to keep average light output constant, then the light output stability is improved, but the laser oscillation becomes unstable and modulation waveform deteriorates at high-speed modulation
Solution Approach 1:
The patent introduces an optical attenuator as an intermediary component between the semiconductor laser and the electro-absorption modulator. This optical attenuator compensates for temperature-induced light output variations without requiring changes to the laser's DC bias current, thereby maintaining both light output stability and laser oscillation stability during high-speed modulation.
Solution Approach 2:
The patent replaces the electrical control method (adjusting DC bias current) with an optical control method (using an optical attenuator to adjust light intensity). This substitution allows for stable light output control without the harmful side effects of reducing DC bias current, preserving laser oscillation stability and modulation performance.
2Adaptability or versatility
If two electro-absorption modulators with different absorption end wavelengths are integrated in series to achieve wide temperature range modulation, then the temperature adaptability is improved, but complicated electric wiring is required to switch modulated signals
Solution Approach 1:
The patent merges the functions of multiple electro-absorption modulators into a single electro-absorption modulator that operates effectively across a wide temperature range. This consolidation eliminates the need for switching mechanisms and complex electric wiring while maintaining the ability to modulate laser light across different temperatures.
Solution Approach 2:
The patent designs a single electro-absorption modulator that performs multiple functions across different temperature ranges, replacing the need for multiple specialized modulators. This universal component handles modulation tasks throughout the entire operating temperature range without requiring complex switching wiring.
3Device complexity
If a single electro-absorption modulator is used instead of multiple modulators, then the device complexity is reduced, but the ability to modulate across wide temperature range is compromised
Solution Approach 1:
The patent utilizes parameter changes in the electro-absorption modulator's characteristics across different temperatures. By designing the modulator to operate effectively across a wide wavelength range and combining it with optical attenuator control, the system achieves wide temperature range modulation capability with a single modulator, eliminating the need for multiple modulators and complex wiring.
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
Enables high-speed modulation in a wide temperature range without complicated electric wiring, ensuring stable modulation waveforms by maintaining constant light output through temperature adjustments.
Implementation Method 1
an electro-absorption modulator and an optical attenuator that are connected in series in a stage succeeding the semiconductor laser
Data Source
AI summary
A modulator-integrated semiconductor laser (100) includes a semiconductor laser (101), an electro-absorption modulator (102), and an optical attenuator (103) that are monolithically integrated. The electro-absorption modulator (102) and the optical attenuator (103) are connected in series in a stage succeeding the semiconductor laser (101). A control unit (44) controls the DC bias voltage to be applied to the optical attenuator (103) to increase as temperature of the modulator-integrated semiconductor laser (100) rises.