Lithium Niobate Optical Modulator with Vπ-Based Voltage Control
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Solution Overview
Problem
Optical modulators using lithium niobate or indium phosphide struggle with high drive voltages and large sizes, making them unsuitable for short/intermediate-range communication within data centers, while silicon-based modulators lack high-frequency operation capabilities.
Innovation Solution
An optical modulator design with a lithium niobate film and controlled electrode voltages, setting Vpp to 0.06×Vπ≤Vpp≤0.4×Vπ and Vn≤Vmin≤Vn+0.29×Vπ or Vn−0.29×Vπ≤Vmax≤Vn, to achieve low-voltage operation with an extinction ratio of 3 dB or larger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If optical modulators using lithium niobate or indium phosphide are used for high-frequency operation, then high-frequency operation capability is achieved, but drive voltage becomes high and device size becomes large
Solution Approach 1:
The patent changes the operating parameters by setting the drive voltage to 0.06×Vπ≤Vpp≤0.4×Vπ, which is lower than the conventional half-wavelength voltage. This parameter change enables high-frequency operation while reducing device size and drive voltage requirements, resolving the contradiction between speed and size.
2Speed
If optical modulators using lithium ni obate or indium phosphide are used for high-frequency operation, then high-frequency operation capability is achieved, but drive voltage becomes high
Solution Approach 1:
The patent changes the operating parameters by setting the drive voltage to 0.06×Vπ≤Vpp≤0.4×Vπ, which is lower than the conventional half-wavelength voltage. This parameter change enables high-frequency operation while reducing drive voltage requirements, resolving the contradiction between speed and power.
3Length of moving object
If silicon-based optical modulators are used for miniaturization and low-voltage driving, then device size is reduced and drive voltage is lowered, but high-frequency operation capability is lost
Solution Approach 1:
The patent uses a composite structure combining lithium niobate film with silicon-based integration techniques. This allows the device to inherit the low-voltage and miniaturization benefits of silicon while maintaining the high-frequency operation capability of lithium niobate, resolving the contradiction between size and speed.
4Power
If silicon-based optical modulators are used for miniaturization and low-voltage driving, then drive voltage is lowered, but high-frequency operation capability is lost
Solution Approach 1:
The patent uses a composite structure combining lithium niobate film with silicon-based integration techniques. This allows the device to inherit the low-voltage benefits while maintaining high-frequency operation capability, resolving the contradiction between power and speed.
5Length of moving object
If drive voltage is reduced to 0.4 Vπ or lower for miniaturization, then device size is reduced, but extinction ratio becomes difficult to maintain at 3 dB or larger
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: sets drive voltage to 0.06×Vπ≤Vpp≤0.4×Vπ, sets minimum voltage Vmin and maximum voltage Vmax within specific ranges relative to null point voltage Vn, and optimizes interaction length. These coordinated parameter changes enable maintaining extinction ratio of 3 dB or larger while achieving miniaturization.
Solution Approach 2:
The patent employs feedback control to adjust the operating point and maintain optimal extinction ratio. By monitoring the output and adjusting the drive parameters dynamically, the system maintains high extinction ratio even at reduced drive voltages and miniaturized dimensions.
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 modulator operates at a drive voltage lower than the half-wavelength voltage, achieving an extinction ratio of 3 dB or larger, suitable for data center applications.
Implementation Method 1
an optical modulation element 100 having a first optical waveguide 11, a second optical waveguide 12, a first electrode 21 configured to apply an electric field to the first optical waveguide 11, and a second electrode 22 configured to apply an electric field to the second optical waveguide 12
Data Source
AI summary
This optical modulator includes an optical modulation element having a first optical waveguide, a second optical waveguide, a first electrode configured to apply an electric field to the first optical waveguide, and a second electrode configured to apply an electric field to the second optical waveguide; and a control unit configured to control an applied voltage between the first electrode and the second electrode. The control unit sets Vpp to 0.06×Vπ≤Vpp≤0.4×Vπ when a half-wavelength voltage of the optical modulation element is Vπ and an applied voltage width that is an amplitude of an applied voltage applied to the optical modulation element is Vpp, and sets Vn≤Vmin≤Vn+0.29×Vπ or Vn−0.29×Vπ≤Vmax≤Vn when a minimum value and a maximum value of a voltage applied to the optical modulation element are respectively Vmin and Vmax and a null point voltage of the optical modulation element is Vn.