Ultra-short Pulse Mid-wave Infrared Laser via 2 μm Pump
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Solution Overview
Problem
Conventional ultra-short pulse lasers for mid wave infrared applications face challenges in achieving high energy per pulse and average power due to low efficiency in nonlinear optical conversion processes and limitations of NLO crystals, resulting in cumbersome and delicate systems with low energy output.
Innovation Solution
An ultra-short pulse infrared laser system utilizing a 2 μm laser source with a stretcher, amplifier stages, nonlinear frequency conversion, and optical parametric chirped-pulse amplification to generate mid and long wave IR beams, achieving high peak power and controllable pulse duration through a compressor, with a ZGP crystal amplifying beams in the 3-8 μm range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional Ti:sapphire or fiber lasers operating at 1 μm are frequency converted to mid wave IR, then ultra-short pulse generation is achieved, but conversion efficiency is low due to high quantum defect and low nonlinear coefficient
Solution Approach 1:
The patent changes the pump laser wavelength parameter from 1 μm to 2 μm, which fundamentally alters the quantum defect and nonlinear optical interaction characteristics. This parameter change enables efficient frequency conversion to mid-wave and long-wave IR regions while maintaining ultra-short pulse duration, directly resolving the low conversion efficiency problem of conventional 1 μm-based systems
Solution Approach 2:
The patent introduces a 2 μm laser source as an intermediary between the pump source and the final mid/long-wave IR output. This intermediary wavelength serves as an optimal bridge that enables efficient nonlinear optical conversion to longer wavelengths while avoiding the limitations of direct 1 μm to mid-IR conversion, thereby achieving high energy per pulse with acceptable efficiency
2Power
If NLO crystals such as GaSe or AgGaSe are used for converting 1 μm sources to mid wave IR, then frequency conversion is achieved, but parasitic effects such as 2 and 3-photon absorption occur at high pump power
Solution Approach 1:
The patent changes the pump wavelength parameter from 1 μm to 2 μm, which shifts the operating regime of the NLO crystals away from the parasitic absorption bands. This parameter change allows the use of the same crystal materials (GaSe, AgGaSe) at higher pump powers without suffering from 2-photon and 3-photon absorption effects, as these parasitic processes are wavelength-dependent and suppressed at the 2 μm pump wavelength
3Power
If multiple amplification stages are added to increase energy per pulse to mJ range, then high energy output is achieved, but system becomes cumbersome and delicate
Solution Approach 1:
The patent changes the pump wavelength to 2 μm, which enables single-stage or reduced-stage amplification to achieve mJ energy per pulse. This parameter change increases the efficiency of each amplification stage, allowing the system to reach high energy output with fewer stages, thereby reducing overall system complexity and eliminating the need for multiple delicate amplification components
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
The system achieves high energy per pulse in the 10s of mJ range with a pulse duration of 100 fs, enabling high peak power and compact, efficient operation capable of creating atmospheric or material effects at km range, with improved conversion efficiencies and reduced dispersion.
Implementation Method 1
an optical parametric chirped-pulse amplification stage for amplification of the mid wave IR or long wave IR beams
Implementation Method 2
a nonlinear frequency conversion stage for generation of mid wave IR or long wave IR seed beams
Implementation Method 3
the non-linear optical element comprises a ZGP crystal and amplifies a beam in the range 3-8 μm
Implementation Method 4
a compressor for controlling and compressing a resulting pulse duration in the mid wave IR or long wave IR beams
Data Source
AI summary
The system and method of using an ultra-short pulse mid and long wave infrared laser. The system is seeded with a 2 μm laser source having a pulse duration in the femtosecond range. The beam is stretched, to increase the pulse duration, and the beam is amplified, to increase an energy level of the laser beam. Both mid wave IR and long wave IR seed beams are first generated, and then amplified via one or more optical parametric chirped-pulse amplification stages. A compressor may be used to compress one or more of the output beams to achieve high peak power and controllable pulse duration in the output beams. The output beams may then be used to create atmospheric or material effects at km range.