Fiber Waveform Multiplexing for High-Power Beam Combining
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Solution Overview
Problem
Conventional fiber amplifiers face limitations in achieving high-power output due to factors like Stimulated Raman Scattering, thermal lensing, and pump power limits, restricting the maximum optical power that can be achieved in a single output waveform, which is particularly challenging for applications such as directed energy weapons that require higher power levels.
Innovation Solution
The method involves generating and co-amplifying input optical waveforms with different polarization states and wavelengths within a single fiber amplifier, followed by combining the amplified waveforms to increase the output power of the combined beam, while using adaptive optical elements to adjust properties like phase, amplitude, and polarization before amplification to avoid thermal and refractive damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single fiber amplifier is used to amplify optical waveforms, then the system structure is simple, but the maximum output power is limited to a few kilowatts due to Stimulated Raman Scattering, thermal lensing, and pump power limits
Solution Approach 1:
The patent divides a single high-power amplification task into multiple lower-power amplification channels. Multiple fiber amplifiers, each operating at moderate power levels below damage thresholds, amplify separate waveforms that are subsequently combined. This segmentation allows the system to achieve high total output power (e.g., tens of kilowatts) while avoiding the nonlinear effects and thermal damage that limit single-fiber amplifiers.
Solution Approach 2:
The patent combines multiple amplified waveforms from separate fiber amplifiers into a single high-power output beam. The waveforms are coherently or incoherently combined after amplification, merging their energies to achieve total output power levels that exceed what any single amplifier could produce. This combining approach resolves the power limitation while distributing the thermal and nonlinear stress across multiple amplifiers.
2Power
If multiple fiber amplifiers are used to achieve high-power output, then the output power increases, but the system size and weight increase
Solution Approach 1:
The patent employs multiple fiber amplifiers that can be configured to amplify different waveforms (different wavelengths, polarizations, or temporal profiles) using the same basic amplifier architecture. This multi-functionality allows a single amplifier design to handle multiple amplification tasks, reducing the need for specialized heavy-duty components and enabling modular scaling of system power output without linearly increasing system weight.
3Adaptability or versatility
If adaptive optical elements are placed before the fiber amplifier, then the optical properties can be adjusted, but the elements are exposed to high power densities that cause thermal and refractive damage
Solution Approach 1:
The patent performs all adaptive optical adjustments (phase modulation, polarization control, beam shaping) on the input waveforms at low power levels before they enter the fiber amplifiers. The adaptive optical elements operate on unamplified or minimally amplified beams, avoiding exposure to the high power densities that would cause thermal damage. After amplification, the already-adjusted waveforms are combined and delivered to the target, eliminating the need for high-power adaptive optics.
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 effectively increases the output power of the combined beam, reduces the number of required fiber amplifiers, and minimizes the size and weight of the system, while also improving compensation for atmospheric turbulence and reducing maintenance costs by avoiding high-power exposure to adaptive optical components.
Implementation Method 1
an amplifier configured to amplify the input optical waveforms to generate an output waveform
Implementation Method 2
CBC can yield a smaller focused spot at the plane of the target or location. Different methods for CBC typically adjust the optical phases, path lengths, and polarizations of waveforms that are generated by a common master oscillator (MO). The waveforms can be amplified by separate fiber amplifiers to provide several kilowatts of output power in each waveform prior to combining the waveforms.
Implementation Method 3
The waveforms are then projected to a common spot in the far field to form a coherently combined output waveform.
Implementation Method 4
at least two of the input optical waveforms have different polarizations
Data Source
AI summary
Systems and methods include a radiation source configured to generate a first waveform, a first separator configured to separate the first waveform into linearly polarized second and third waveforms, a first modulator configured to modulate at least one of a phase and a polarization of the second waveform to generate a fourth waveform, a second modulator configured to modulate at least one of a phase and a polarization of the third waveform to generate a fifth waveform, a first combiner configured to combine the fourth and fifth waveforms to generate a sixth waveform, an amplifier configured to amplify the sixth waveform to generate a seventh waveform, a second separator configured to separate the seventh waveform into a plurality of amplified waveforms, and beam directing optics configured to direct the plurality of amplified waveforms to form an output waveform at a target location.