Dual OPA System for Broad Visible to Infrared Spectrum Generation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical amplifier arrangements struggle to generate a broad visible to infrared spectrum of coherent ultra-short light pulses efficiently, particularly at lower pulse energies and longer pulse durations, and face challenges in tunability and stability, especially when conditions deviate from the optimal Ti:Sa laser parameters.
Innovation Solution
The use of a dual optical parametric amplifier system with intermediate non-linear spectral broadening, where the first optical parametric amplifier generates a red-shifted pulse from a white light continuum, which is then used to seed the second optical parametric amplifier, allowing for continuous tunability across a wide wavelength range through harmonic generation and frequency doubling, using a pump laser with wavelengths above 950 nm and pulse durations up to several hundred femtoseconds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single optical parametric amplifier is used with standard Ti:Sa laser pumping, then high pulse energy and short pulse duration can be achieved, but the spectral bandwidth and tunability range are limited
Solution Approach 1:
The system divides the amplification process into two separate optical parametric amplifiers (OPA1 and OPA2) with different pumping schemes. OPA1 uses second harmonic pumping for generating the blue-shifted continuum, while OPA2 uses fundamental pumping for generating the final broad spectrum. This segmentation allows each amplifier to be optimized for its specific function, achieving extended spectral bandwidth without excessive complexity in a single stage.
Solution Approach 2:
The invention extends the spectral coverage by utilizing two different pump wavelengths (fundamental and second harmonic) to excite the OPAs. This adds a dimensional aspect to the spectral generation, where each pump wavelength contributes to a different portion of the output spectrum, ultimately achieving a broad continuous spectrum from 500 nm to 5 μm that cannot be obtained with a single pump wavelength.
2Reliability
If pump laser wavelength is increased above 950 nm with longer pulse durations, then efficiency and stability improve, but the achievable spectral bandwidth decreases
Solution Approach 1:
The system employs two different pump wavelengths (fundamental >950 nm and second harmonic) to excite the two OPAs. By changing the pump wavelength parameter for each stage, the system achieves both high stability (from fundamental pumping in OPA2) and broad spectral bandwidth (through the combined output of both stages). Each OPA is optimized for its specific pump wavelength to maintain stability while extending the overall spectral coverage.
3Adaptability or versatility
If dual OPA system with different pump wavelengths is implemented, then broad tunable spectrum is achieved, but system complexity and alignment requirements increase
Solution Approach 1:
The blue-shifted continuum generated by OPA1 serves as an intermediary seed source for OPA2. This intermediary spectrum acts as the input for the second amplifier, allowing the system to achieve broad spectral tunability through a cascaded configuration. The intermediary stage bridges the gap between the two pump wavelengths, enabling versatile spectral output while managing the complexity through a systematic multi-stage approach.
4Productivity
If second harmonic pumping is used for spectral broadening, then white light generation efficiency improves, but pulse energy requirements increase
Solution Approach 1:
The system segments the white light generation process into two stages with different pumping schemes. OPA1 uses second harmonic pumping for efficient white light generation in the visible-NIR range, while OPA2 uses fundamental pumping to extend the spectrum to mid-IR. This segmentation allows each stage to operate at optimized energy levels, achieving high overall productivity without requiring excessive pulse energy at a single stage.
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 approach enables the generation of a gapless, tunable broad visible to infrared spectrum of coherent ultra-short light pulses with improved stability and coherence, covering wavelengths from 500 nm to 5 μm, even under less favorable conditions, and allows for efficient use of pump energy across a range of pulse lengths and energies.
Implementation Method 1
at least a first optical parametric amplifier (OPA1) and a second optical parametric amplifier (OPA2) pumped and seeded at different wavelengths; i. H. at the input with input pulses (seed pulses) are applied, which are amplified by means of a conversion process with temporal and spatial overlapping of a seed pulse with a pump pulse in a non-linear medium, such as a non-linear crystal or the like, in the OPA
Implementation Method 2
This red-shifted pulse is then used to generate a gapless, comparatively extremely wide continuum of light of relatively lower intensity. This happens through a further non-linear interaction in a medium, preferably solid, where a strong spectral broadening takes place - this is also referred to in its broad meaning as white light generation. (WLC2). The processes that play a role in white light generation (WLC, in particular WLC1 and WLC2) are known in English under the terms 'self phase modulation’, 'filamentation’, 'supercontinuum generation' and 'white light generation'.
Implementation Method 3
the second of the system's two optical parametric amplifiers is seeded with stretched pulses directly from the first optical parametric amplifier for amplification with the second harmonic pump pulses of the pulses from the amplifier in the second of the system's two optical parametric amplifiers
Implementation Method 4
harmonic generation optically coupled such that in use the first optical parametric amplifier is seeded by the first white light generation and the second optical parametric amplifier is seeded by the second white light generation, and wherein in use the first white light generation and the first optical parametric amplifier and the harmonic generation are pumped by a fundamental of a laser
Data Source
Figure 1A~1B
Figure 2
Figure 3A
AI summary
The invention relates to an optical amplifier arrangement comprising optical parametric amplifiers and white light generation and harmonic generation, in particular frequency doubling, for generating a broad visible to infrared, or at least near-infrared, spectrum of coherent ultra-short light pulses, in particular with a pump laser, and a method for generating a broad visible to infrared, or at least near-infrared, spectrum of coherent ultra-short light pulses with an optical amplifier arrangement.According to the invention, it is provided that in operation the fundamental lies in a wavelength range above 950 nm, and the second signal light and the second idler light of the second optical parametric amplifier together cover a tuning range of wavelengths between 500 nm and 5 µm, in particular between 550 nm and 3 µm, wherein continuous tuning between wavelengths in the tuning range is possible, namely continuous tuning through the degeneration range of the second optical parametric amplifier (OPA2) at the fundamental of the pump laser.