Pulsed Laser Using Birefringent Element for Dual Frequency Comb
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Solution Overview
Problem
Existing radiation sources for generating frequency combs, such as dual pulsed lasers, are expensive and complex, making them impractical for industrial applications due to the need for multiple optical components.
Innovation Solution
A radiation source with a laser gain element, a mode locker, and a birefringent element within a shared laser resonator, which generates two trains of pulses with slightly different repetition rates and spectral frequencies, reducing the complexity and cost by using a common gain element and optical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate pulsed lasers are used to generate frequency combs, then the required spectral properties and pulse repetition rates can be achieved, but the system becomes expensive and complex with lots of optical components
Solution Approach 1:
The patent combines two separate pulsed laser systems into a single laser resonator by introducing a birefringent element that spatially separates the intracavity radiation into two polarization states. This merging approach maintains the functionality of generating two frequency combs with slightly different pulse repetition rates while drastically reducing the number of optical components and system complexity
Solution Approach 2:
The birefringent element segments the single laser beam into two distinct polarization states (ordinary and extraordinary rays) that travel through the resonator with different optical path lengths. This segmentation enables the generation of two separate pulse trains with different repetition rates from a single laser gain element
2Reliability
If two separate pulsed lasers are used to generate frequency combs, then the required spectral properties and pulse repetition rates can be achieved, but the manufacturing and operating costs increase significantly
Solution Approach 1:
The patent merges two separate laser systems into one shared resonator configuration, allowing both frequency combs to be generated using a single gain element, shared pump arrangement, and common optical components. This significantly reduces manufacturing costs and operational expenses while maintaining the required dual-comb functionality
3Device complexity
If a single laser resonator is used with a birefringent element, then the system complexity and cost are reduced, but the generation of two distinct pulse trains with different repetition rates must be achieved
Solution Approach 1:
The birefringent element introduces local quality differences within the laser resonator by creating two distinct optical path lengths for the two polarization states. This local differentiation in optical path length enables the generation of two pulse trains with different repetition rates while using a single shared resonator structure
Solution Approach 2:
The patent changes the optical path length parameter for each polarization state within the resonator. By controlling the birefringence and resonator geometry, the optical path lengths for the ordinary and extraordinary rays are differentiated, resulting in different pulse repetition rates while maintaining a compact single-resonator 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
This setup allows for the generation of coherent frequency combs with a broad bandwidth, overcoming the cost and complexity issues of traditional dual laser systems, enabling applications like multi-heterodyne spectroscopy and asynchronous optical sampling with reduced operational expenses.
Implementation Method 1
The mode locker causes the radiation in the laser resonator (intracavity radiation) to be pulsed radiation. This ensures that output radiation has a certain spectral width making a plurality of peaks in the optical spectrum and consequently a frequency comb possible.
Implementation Method 2
The birefringent element causes portions of the intracavity radiation of different polarization states to be spatially separated. As a consequence, the optical path length of radiation may, and generally will, depend on the polarization.
Implementation Method 3
an optical arrangement defining a laser resonator and arranged to re-direct radiation emitted by the gain element along a beam path back onto the gain element
Implementation Method 4
an output coupler configured to couple a portion of the radiation in the laser resonator out of the laser resonator
Implementation Method 5
a pump arrangement configured to pump the laser gain element
Data Source
AI summary
An apparatus for emitting pulsed electromagnetic laser radiation includes a laser gain element; an optical arrangement defining a laser resonator and arranged to re-direct radiation emitted by the gain element along a beam path back onto the gain element, the optical arrangement comprising an output coupler configured to couple a portion of the radiation in the laser resonator out of the laser resonator; and, a pump arrangement configured to pump the laser gain element. The optical arrangement includes a mode locker placed in the laser resonator in the beam path, and a birefringent element placed in the laser resonator in the beam path.