Optical Modulator Asymmetric Termination Resistor Impedance
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Solution Overview
Problem
Existing optical modulators that drive LN optical modulation elements using differential signals from semiconductor drive circuit elements can experience operational destabilization and inefficient power consumption due to signal reflection and unnecessary power output.
Innovation Solution
An optical modulator configuration that includes an optical waveguide element with a signal electrode, a drive circuit outputting two high-frequency signals, and two terminating resistors, where one high-frequency signal is terminated by a first resistor and the other by a second resistor with a greater resistance value, optimizing impedance matching and power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a drive circuit element outputting differential signals is used to drive an LN optical modulation element requiring only one signal, then the existing semiconductor optical modulation module can be utilized, but signal reflection occurs causing operational destabilization
Solution Approach 1:
A terminating resistor is introduced as an intermediary component connected to the unused output terminal of the differential drive circuit. This resistor absorbs the unused high-frequency signal, preventing it from reflecting back into the circuit and causing instability, while allowing the drive circuit to remain compatible with the single-signal LN optical modulation element
Solution Approach 2:
The unused output terminal, which originally caused harmful signal reflections and operational instability, is converted into a beneficial configuration by connecting a terminating resistor. This transforms the potential source of instability into a controlled impedance termination that stabilizes the entire drive circuit system
2Device complexity
If the unused output terminal of the drive circuit is left connected to circuit components, then the circuit is complete, but unnecessary signal power is consumed reducing power efficiency
Solution Approach 1:
The unnecessary signal power output from the unused terminal is extracted and dissipated as heat through the terminating resistor, rather than being circulated uselessly through the circuit. This removes the waste energy path while maintaining circuit completeness
Solution Approach 2:
By changing the impedance parameter of the unused terminal through the terminating resistor, the circuit transforms from a state that circulates unnecessary power to one that efficiently dissipates it, optimizing the power consumption characteristics of the drive circuit
Data Source
AI summary
An optical modulator includes: an optical waveguide element including an optical waveguide formed on a substrate and a signal electrode for controlling a light wave propagating through the optical waveguide; a drive circuit for outputting two high-frequency signals; and two terminating resistors for respectively terminating outputs of the two high-frequency signals from the drive circuit. The output of one of the high-frequency signals of the drive circuit propagates through the signal electrode of the optical waveguide element and is terminated by a first terminating resistor which is one of the terminating resistors. The output of the other of the high-frequency signals of the drive circuit is terminated by a second terminating resistor which is the other of the terminating resistors. A resistance value of the second terminating resistor is greater than a resistance value of the first terminating resistor.