Optical Modulator Module With Segmented Electrodes
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Solution Overview
Problem
Current optical modulators face limitations in generating multilevel optical modulation signals at high speeds and low driving voltages, particularly due to attenuation of modulation electric signals, which affects modulation bandwidth and reliability, especially in high-frequency regions exceeding 40 Gb/s.
Innovation Solution
A compact optical modulator module with cascaded individual driving circuits and phase shift circuits that amplify digital input signals and apply delays to achieve phase velocity matching and impedance matching, allowing for longer effective optical modulator lengths and reduced driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional single-stage optical modulator is used, then the device structure is simple, but the modulation bandwidth is limited and driving voltage is high at frequencies over 1 GHz
Solution Approach 1:
The optical modulator is divided into multiple stages (first stage, second stage, etc.), each with its own phase modulator and drive circuit. This segmentation allows each stage to operate at lower individual bandwidth requirements while achieving higher overall modulation bandwidth through cascaded operation, resolving the contradiction between structural simplicity and high-speed performance.
Solution Approach 2:
The patent implements dynamic phase velocity matching between optical signals and electrical signals in each stage by adjusting electrode configurations and impedance values. This dynamic optimization enables each stage to operate efficiently at high frequencies, achieving broadband operation while maintaining reasonable structural complexity.
2Length of moving object
If the electrode length is increased to improve phase velocity matching, then the interaction length with optical signal increases, but the modulation electric signal attenuates significantly at high frequencies
Solution Approach 1:
The total electrode length is divided into multiple shorter electrode segments across different stages. Each segment interacts with the optical signal over a shorter distance, reducing attenuation of the modulation electric signal at high frequencies, while the cascaded stages collectively provide sufficient total interaction length for effective modulation.
Solution Approach 2:
The patent dynamically optimizes the length and impedance of each electrode segment to match the phase velocity of the optical signal at each stage. This dynamic phase velocity matching maximizes the effective interaction length without excessive attenuation, as each stage is optimized for its specific operating conditions.
3Volume of moving object
If a single-stage design is used, then the device is compact, but high driving voltage is required to achieve sufficient modulation depth
Solution Approach 1:
The modulation function is segmented across multiple stages, each contributing a portion of the total modulation depth. This allows the use of lower driving voltages at each stage while achieving the same overall modulation depth as a single high-voltage stage, reducing total power consumption while maintaining compact size through integrated cascaded structure.
Solution Approach 2:
Multiple modulation stages are merged into a single cascaded device where the modulation effects combine multiplicatively. This merging allows the system to achieve high modulation depth with lower individual stage voltages, reducing overall power consumption while maintaining a compact integrated form factor.
4Speed
If the optical modulator length is extended to improve modulation performance, then the bandwidth is enhanced, but the module size increases significantly
Solution Approach 1:
The optical modulator is segmented into multiple compact stages arranged in a cascaded configuration. Each stage provides a portion of the total bandwidth enhancement, allowing the system to achieve high overall bandwidth without requiring a single excessively long modulator structure, thus controlling the total module length.
Solution Approach 2:
Instead of extending the modulator in a single dimension to increase length, the patent uses a cascaded multi-stage configuration that achieves bandwidth enhancement through temporal sequencing of modulation events. This dimensional transformation allows bandwidth scaling without proportional increases in physical length.
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 enables the generation of multilevel optical modulation signals with improved bandwidth and reduced driving voltage, enhancing the reliability and efficiency of high-speed optical modulation, particularly in next-generation optical fiber communication systems.
Implementation Method 1
waveguide-type optical phase modulator regions... in which the refractive index of an optical waveguide is changed by applying an electric field
Data Source
AI summary
The present invention provides a compact, broad-band, and low-drive-voltage optical modulator module capable of generating any multilevel optical modulation. The optical modulator module according to an exemplary aspect of the present invention includes a digital segmented electrode structure optical modulator and m individual driving circuits. The digital segmented electrode structure optical modulator includes semiconductor optical waveguides and at least m waveguide-type optical phase modulator regions. An i-th individual driving circuit includes a driving circuit and a phase shift circuit. The driving circuit amplifies a digital input signal in synchronization with a clock signal and outputs the signal to an i-th waveguide-type optical phase modulator region. The phase shift circuit applies a delay to a signal branched from the clock signal. A j-th individual driving circuit receives an output signal from the phase shift circuit of a (j−1)-th individual driving circuit as a clock signal.