Coherent Beam Combining for Fast Laser Modulation Without Power Loss
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Solution Overview
Problem
Current methods for manipulating high power laser beams are slow and can damage components due to inefficient power manipulation and mismatched optical and mechanical alignment in fiber laser systems, leading to energy loss and susceptibility to parasitic processes like stimulated Brillouin scattering.
Innovation Solution
A method involving a coherent beam combining system with phase modulators and control circuitry to actively control laser beam interference, allowing for rapid activation and deactivation of laser beams without power reduction, and a hybrid fiber-coupled diode pump laser module to reduce fusion points and energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If power manipulation methods are used to activate/deactivate laser beams, then the laser beam can be controlled, but the manipulation speed is slow (1-5 KHz) and components may be damaged
Solution Approach 1:
The system segments the laser beam into multiple individual beams, allowing independent control of each beam through separate phase modulators. This enables fast on/off switching at the individual beam level without requiring power manipulation of the entire laser system, thus achieving high-speed control (10 GHz) while preventing component damage.
Solution Approach 2:
The patent replaces mechanical/power-based beam control with phase modulation control. Instead of manipulating laser power to activate/deactivate beams, the system uses phase modulators to control the interference conditions, substituting a non-mechanical, non-power-intensive control mechanism that operates at much higher speeds without damaging components.
2Manufacturing precision
If tapered fiber bundle is used to match fiber diameters, then coupling is achieved, but numerical aperture increases and mode field diameter changes causing misalignment
Solution Approach 1:
The patent introduces a mode field adapter as an intermediary component between the tapered fiber bundle and the output pigtail fiber. This adapter serves as a transition element that gradually transforms the mode field diameter and numerical aperture, reducing abrupt changes and minimizing misalignment issues while maintaining effective fiber coupling.
Solution Approach 2:
The system employs parameter changes by using a mode field adapter that gradually transforms optical parameters (mode field diameter and numerical aperture) between the tapered fiber bundle and output fiber. This gradual parameter transformation reduces abrupt mismatches, improving alignment precision while managing the complexity of optical matching.
3Loss of energy
If signal fiber is tapered down with pump fibers, then coupling is improved, but core diameter becomes small causing mismatch with large mode area double clad fibers
Solution Approach 1:
The patent segments the fiber coupling process into distinct stages: first tapering the pump fibers and signal fiber together for initial coupling, then introducing a separate mode field adapter section that specifically addresses the core diameter mismatch between the tapered signal fiber and the large mode area double clad fiber. This segmented approach allows optimization of each coupling stage independently.
Solution Approach 2:
A mode field adapter acts as an intermediary section between the tapered signal fiber and the large mode area double clad fiber. This adapter gradually transforms the core diameter from small to large, reducing abrupt mismatches and minimizing signal insertion loss while maintaining manufacturing feasibility.
4Speed
If fast modulation is implemented to achieve high frequency control, then beam activation/deactivation speed increases, but system complexity increases
Solution Approach 1:
The patent merges the control functions by using a single phase modulator that simultaneously controls multiple parameters (beam activation, deactivation, and intensity modulation) through unified phase modulation. This consolidation achieves high-frequency control (10 GHz) while reducing the number of separate control components compared to traditional power manipulation systems.
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 high-frequency modulation of laser beams up to 10 GHz without damaging components, reducing energy loss and improving beam quality by maintaining system power during modulation.
Implementation Method 1
plurality of phase modulators configured in (direct or indirect) optical connections with: the seed beam, plurality of optical amplifiers, at least one beam splitter, and optionally at least one beam combiner; all arranged to enable constructive or destructive beam interference
Implementation Method 2
all arranged to enable constructive or destructive beam interference, at a CBC point
Implementation Method 3
A common method to couple a pump and/or a signal light with a doped fiber is via a fused coupler, which is a fiber combiner or a fused tapered fiber bundle (TFB), based on end face pumping technique
Implementation Method 4
In order to match the diameter of the fiber bundle to the diameter of the output pigtail fiber, the bundle is slowly melted and tapered
Implementation Method 5
High power fiber lasers and fiber amplifiers require high brightness pump source and efficient techniques to be coupled with a doped fiber, in order to excite the ions and initiate a lasing process
Implementation Method 6
Their susceptibility to parasitic non-linear processes, primarily stimulated Brillouin scattering (SBS), which occurs when the laser signal has a line-width narrower than a few tens of megahertz
Data Source
AI summary
Methods and apparatuses for manipulating and modulating of laser beams. The methods and apparatuses enable activating and deactivating of laser beams, while the laser systems maintain their operating power. Further, a hybrid pump module configured to be coupled to an optical fiber having a core and at least one clad, comprising: at least one focusing lens in optical with the optical fiber; plurality of diode modules, each configured to output a multi-mode beam in optical path with the clad; and at least one core associated module, in optical path with the core, configured to provide selected functions. Further, apparatus and methods configured for frequency doubling of optical radiation.