Optical Resonator Amplitude Modulation via Feedback
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Solution Overview
Problem
Current methods for modulating high-frequency light pulses, particularly in the femtosecond range, are limited by mechanical choppers, electro-optical modulators, and directly modulated diodes, which require expensive power electronics and are technically demanding, failing to achieve efficient and cost-effective modulation.
Innovation Solution
An optical system with an optical resonator and optically non-linear frequency conversion medium that converts pump light pulses into two conversion light pulses and a residual pump light pulse, using a feedback arm with an optically non-linear feedback medium for passive amplitude modulation, eliminating the need for expensive power electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If mechanical choppers are used to modulate light pulses, then the modulation can be achieved, but the modulation frequency is limited to only a few 10 kHz
Solution Approach 1:
The patent replaces mechanical choppers with an optical resonator system that uses optical feedback and non-linear frequency conversion to achieve high-frequency modulation. The mechanical moving parts are eliminated in favor of an all-optical modulation mechanism that operates at frequencies up to the gigahertz range.
Solution Approach 2:
The patent employs periodic feedback of light pulses through the optical resonator, where the feedback arm reflects a portion of the pulses back into the resonator at controlled intervals. This periodic optical action enables high-frequency modulation without mechanical components.
2Speed
If electro-optical modulators or acousto-optical modulators are used, then modulation can be achieved, but they are limited to a maximum modulation range of approximately 50 MHz and require expensive power electronics
Solution Approach 1:
The patent substitutes electro-optical and acousto-optical modulators with a purely optical feedback mechanism. The modulation is achieved through optical interference and non-linear frequency conversion within the resonator, eliminating the need for expensive power electronics and control systems.
Solution Approach 2:
The optical resonator system is self-modulating through its own feedback mechanism. The system uses a portion of its output light to modulate itself via the feedback arm, eliminating the need for external power electronics and control systems that would otherwise be required.
3Duration of action of moving object
If directly modulated diodes are used, then modulation can be achieved, but they are limited to modulating pulses with a maximum length of a few 100 picoseconds or nanoseconds and cannot modulate pulses in the femtosecond range
Solution Approach 1:
The patent uses periodic feedback of ultra-short light pulses through the optical resonator. The feedback mechanism maintains the short duration of femtosecond pulses while enabling high-frequency modulation, as the optical feedback occurs on timescales compatible with ultra-short pulse durations.
Solution Approach 2:
The patent changes the operational parameters of the optical system by using non-linear frequency conversion and optical feedback, which enables the system to handle and modulate femtosecond-scale pulses that would be impossible to modulate with conventional diode-based systems.
4Reliability
If conventional modulation methods are used, then modulation can be achieved, but the costs are high due to expensive power electronics and control electronics
Solution Approach 1:
The optical resonator system modulates itself using its own output light reflected through the feedback arm. This self-service mechanism eliminates the need for external power electronics and control electronics, significantly reducing system cost while maintaining reliable high-frequency modulation capability.
Solution Approach 2:
The patent replaces expensive electronic control systems with a purely optical feedback mechanism. The modulation is achieved through optical interference and non-linear frequency conversion, eliminating the need for costly power electronics and control electronics while maintaining reliable modulation performance.
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-frequency modulation of light pulses up to the gigahertz range with reduced costs and complexity, achieving stable amplitude modulation suitable for various applications, including Raman microscopy.
Implementation Method 1
An optically non-linear frequency conversion medium for converting the pump light pulses into two conversion light pulses and one residual pump light pulse is arranged in the resonator
Implementation Method 2
An optically non-linear feedback medium for optical modulation of the at least one conversion light pulse and/or the residual pump light pulse, for which the feedback arm is designed and provided, is arranged in the feedback arm
Data Source
Figure 1~2b
Figure 3~4
Figure 5
AI summary
Optical system and method for providing at least one high-frequency modulated light pulse (30; 31), comprising a pump light source (55) for providing high-frequency pump light pulses (10); an optical resonator (20) with an input coupling element (21) for coupling the pump light pulses (10) into the resonator (20) and an output coupling element (22) for coupling the at least one high-frequency modulated light pulse (30; 31) out of the resonator (20) and an optically nonlinear frequency conversion medium (25) arranged in the resonator (20) for converting the pump light pulses (10) into two conversion light pulses and one residual pump light pulse (31). The resonator (20) has a feedback arm (24) for at least one of the two conversion light pulses and/or the residual pump light pulse (31), in which an optically nonlinear feedback medium (26) is arranged for optical modulation of the at least one conversion light pulse and/or the residual pump light pulse (31).