Wavelength Tunable Laser Phase Control via Negative Bias
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Solution Overview
Problem
Conventional wavelength tunable laser apparatuses face challenges in achieving sufficient wavelength shift with minimal optical loss and power consumption, leading to increased costs and reduced reliability due to the need for higher current densities and larger device sizes.
Innovation Solution
A method utilizing a negative bias applied to the phase control region, in conjunction with a current source, to shift wavelengths through the Franz-Keldysh effect, allowing for a larger wavelength shift with lower optical absorptivity and reduced power consumption, thereby enabling a smaller, more efficient device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the amount of current is increased to increase wavelength shift, then the wavelength shift increases, but the optical absorptivity increases and optical output deteriorates
Solution Approach 1:
The patent changes the operating parameters of the phase control region by applying negative bias voltage instead of increasing positive current. This parameter change allows achieving the desired wavelength shift while maintaining low optical absorptivity and high optical output, resolving the contradiction between wavelength shift and optical loss
2Ease of operation
If the length of the phase control region is elongated to increase wavelength shift, then the wavelength shift increases, but the device size increases
Solution Approach 1:
The patent achieves increased wavelength shift by changing the electrical parameter (applying negative bias) rather than increasing the physical dimension (length). This allows achieving the desired wavelength shift capability while maintaining a compact phase control region length, resolving the contradiction between wavelength shift and device size
3Ease of operation
If higher current density is used to achieve sufficient wavelength shift, then the wavelength shift increases, but power consumption increases and reliability decreases
Solution Approach 1:
The patent changes the current application mode from high positive current density to negative bias voltage, which achieves the desired wavelength shift while significantly reducing power consumption and improving device reliability. This parameter change resolves the contradiction between wavelength shift and reliability
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 enables a wavelength tunable laser apparatus with enhanced performance, increased yields, and reduced costs, facilitating higher capacity and longer-distance optical communication systems while maintaining low optical loss.
Implementation Method 1
A method utilizing a negative bias applied to the phase control region, in conjunction with a current source, to shift wavelengths through the Franz-Keldysh effect
Data Source
AI summary
Included are: a gain chip having a gain unit and a phase control region; a current supply for causing a positive current to flow to the phase control region; a voltage supply for applying a bias voltage to the phase control region; and a control unit for selectively driving the current supply or the voltage supply depending on a direction of the wavelength shift. The control unit drives the current supply when a laser wavelength is to be shifted to a shorter wavelength side from a wavelength with the current supply and the voltage supply being turned off, and drives the voltage supply when the laser wavelength is to be shifted to a longer wavelength side from a wavelength with the current supply and the voltage supply being turned off.