Laser Resonator Phase Shifter for Offset Frequency Control
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Solution Overview
Problem
Conventional methods for adjusting the offset frequency of a frequency comb in laser devices can only achieve precise control over a limited frequency range, restricting the flexibility and accuracy in generating or fine-tuning short or ultrashort laser pulses.
Innovation Solution
The introduction of a phase shifter that imparts a geometric phase to the carrier wave of the laser pulse within the resonator, allowing for independent adjustment of the offset frequency without altering the group circulation time or mode distance, using adjustable birefringent or polarizing elements to vary the geometric phase and thus control the offset frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to adjust the offset frequency of a frequency comb, then the offset frequency can be controlled, but the adjustment range is limited and the mode distance is affected
Solution Approach 1:
The patent segments the control of frequency comb parameters by introducing a dedicated phase shifter that independently controls the offset frequency, separating this control function from the mode distance control. This allows the offset frequency to be adjusted without affecting the mode distance, thereby expanding the adjustment range while maintaining precision.
Solution Approach 2:
The patent changes the physical parameter being controlled by introducing a phase shifter that directly modifies the phase of the carrier wave. By controlling the phase shift parameter, the offset frequency can be independently adjusted across a wider range without the limitations of conventional methods that simultaneously affected both mode distance and offset frequency.
2Ease of operation
If the offset frequency is adjusted using conventional methods, then some frequency control is achieved, but the mode distance and group circulation time are also altered
Solution Approach 1:
The patent extracts the offset frequency control function from the overall frequency comb adjustment process by introducing a dedicated phase shifter. This separate component specifically targets the offset frequency parameter, allowing it to be adjusted independently without disturbing the mode distance and group circulation time, thus maintaining system stability while improving operational ease.
Solution Approach 2:
The phase shifter acts as an intermediary element between the control system and the frequency comb parameters. It mediates the adjustment process by selectively modifying only the offset frequency through phase modulation, while leaving other critical parameters like mode distance unchanged, thereby resolving the contradiction between ease of adjustment and parameter stability.
3Adaptability or versatility
If a phase shifter is introduced to independently control offset frequency, then wide-range adjustment is achieved, but the device complexity increases
Solution Approach 1:
The phase shifter is designed with multi-functionality, serving both to expand the offset frequency adjustment range and to maintain compatibility with existing resonator configurations. By making the phase shifter a universal component that can be integrated into various resonator arrangements without requiring fundamental system redesign, the patent minimizes the increase in device complexity while achieving enhanced adaptability.
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 precise and wide-range adjustment of the offset frequency of frequency combs, maintaining the mode distance and group circulation time stability, thereby enhancing the control and flexibility in generating and fine-tuning laser pulses.
Implementation Method 1
varying a geometric phase which imparts a phase lag in comparison to the unvaried state to the carrier wave (12) of the laser pulse (10) per circulation in the resonator (1)
Implementation Method 2
at least one birefringent or polarizing element (7) being variable in its orientation
Data Source
AI summary
A method for operating a laser device, including providing a laser pulse in a resonator so that the laser pulse circulates in the resonator, the laser pulse having a carrier wave; determining an offset frequency (f0) of the frequency comb corresponding to the laser pulse, the frequency comb having a plurality of laser modes (fm) at a distance (frep) from one another, the frequencies of which can be described by the formula: fm=m*frep+f0, m being a natural number, and varying the offset frequency (f0) by varying a geometric phase (Δφ) that is imparted to the carrier wave of the laser pulse per resonator circulation.