Integrated Electro-Optic Modulator for Low-Power Distance Measurement
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Solution Overview
Problem
Current Fizeau-principle based distance-measuring devices using bulk electro-optic modulators require high voltages and power consumption, limiting measurement rate due to mechanical tuning needs and unsuitability of single-pass modulators for bidirectional light passage.
Innovation Solution
An integrated optics modulator with a nonlinear optical material and traveling wave electrodes, providing symmetrical electro-optic response for forward and backward light directions, reducing voltage requirements and power consumption, and enabling high-frequency modulation with minimal mechanical tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bulk electro-optic modulators are used in Fizeau-principle based distance-measuring devices, then distance measurement function is achieved, but high voltage and power consumption are required
Solution Approach 1:
The patent replaces bulk electro-optic modulators with integrated optics modulators, substituting a mechanical/optical system with an integrated photonic system. This integration reduces the physical size and eliminates the need for high-voltage electrical fields, thereby reducing power consumption while maintaining distance measurement functionality through optical interference principles.
Solution Approach 2:
The invention changes the operating parameters from high-voltage electrical modulation to low-power optical modulation. By using integrated waveguide structures with embedded phase modulators, the system achieves the same electro-optic modulation effect with significantly reduced voltage and power requirements, transforming the operational regime from high-power electrical to low-power optical domain.
2Measurement precision
If bulk electro-optic modulators with mechanical tuning are used, then distance measurement is achieved, but measurement rate is limited
Solution Approach 1:
The patent eliminates mechanical tuning components by using integrated optics modulators with electronic or optical control mechanisms. The phase modulation is achieved through integrated waveguide phase shifters controlled by low-power electrical signals or optical pumping, replacing mechanical resonator tuning with solid-state phase control, thereby enabling high-speed measurement rates without mechanical movement limitations.
3Device complexity
If single-pass modulators are used, then simple structure is achieved, but bidirectional light passage is unsuitable
Solution Approach 1:
The patent employs symmetrical bidirectional modulator designs where the optical path and phase modulation characteristics are identical for both forward and backward propagating light. This symmetry ensures that the interferometric measurement works correctly regardless of light propagation direction, enabling the Fizeau principle to function with integrated optics modulators while maintaining structural simplicity through uniform waveguide and modulator placement.
Solution Approach 2:
The integrated optics modulator is designed to serve multiple functions: it acts as both the modulation element and the reference path element in the interferometric setup. The same waveguide structure handles both the measurement light and reference light, providing universal functionality that simplifies the overall device architecture while enabling bidirectional operation through proper coupling scheme design.
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-accuracy, high-rate distance measurements with low power consumption and eliminates the need for external resonators and mechanical tuning, allowing for efficient operation in applications requiring GHz frequency modulation.
Implementation Method 1
An integrated electro-optic modulator is provided comprising an optical waveguide of a nonlinear optical material and travelling wave electrodes arranged to generate an electrical field in a modulating region of the waveguide when a voltage is applied to the electrodes, thereby modulating the phase of light passing through the waveguide
Data Source
Figure 1~3b
Figure 2a~4
AI summary
A distance measuring device comprises a light source (101) emitting light, and such an integrated electro-optic modulator (21, 22, 23) arranged such that the emitted light passes through an optical waveguide of the electro-optic modulator (21, 22, 23) in a first direction before being emitted from the distance measuring device, and after being reflected from a target passes through the electro-optic modulator (21, 22, 23) in a second direction which is opposite to the first direction, The forward electro-optic response of a modulating region (17) of the electro-optic modulator (21, 22, 23) is the same as the backward electro-optic response, and a centre of gravity of the modulation is independent of modulation frequency.