All Fiber Pulse Generator for Non-Linear Converter Pumping

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Solution Overview

Problem

Fiber lasers and amplifiers require significant pumping power to produce high power output and have inefficiencies due to extensive opto-mechanical architectures, which are costly and difficult to align and maintain, and also limit the efficiency of non-linear converters like optical parametric oscillators.

Innovation Solution

A fiber laser and amplifier system with few or no opto-mechanical elements, utilizing Thulium-doped silica fibers and narrow spectral bandwidth Bragg gratings to achieve high efficiency and ease of alignment, with all-fiber implementation and diode laser pumps to generate and amplify mid-IR wavelengths, eliminating free space coupling until output to a nonlinear converter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If fiber lasers and amplifiers use extensive opto-mechanical architectures with crystal lasers, lenses, and mechanical mounts, then they can achieve high power output, but the systems become complex, costly, and difficult to align and maintain

Engineering Contradiction:

Improvehigh power outputVSAvoidcomplexity of opto-mechanical architecture

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent replaces traditional opto-mechanical architectures (crystal lasers, lenses, mechanical mounts) with an all-fiber architecture where fiber lasers and amplifiers directly generate and amplify laser beams. This eliminates the need for complex mechanical alignment and mounting systems while maintaining high power output capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent combines the laser generation and amplification functions into an integrated all-fiber system. The fiber amplifier is directly coupled to the fiber laser, merging multiple optical components into a unified fiber-based architecture that reduces complexity while preserving power output.

Inventive Principle:

Principle #5Merging (Combining)

2Productivity

If fiber lasers use wide spectral bandwidth, then they can operate efficiently, but the efficiency of non-linear converters like optical parametric oscillators decreases

Engineering Contradiction:

Improveoperational efficiency of fiber laserVSAvoidefficiency of non-linear converter

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent applies different spectral bandwidth characteristics to different parts of the system. The fiber laser operates with a broader spectral bandwidth for high efficiency, while the non-linear converter is designed to handle and optimize the specific spectral characteristics of the pumped beam, creating local optimization throughout the system.

Inventive Principle:

Principle #3Local quality

3Power

If fiber lasers require significant pumping power to produce high power output, then they can achieve high power levels, but the overall system efficiency decreases

Engineering Contradiction:

Improvehigh power outputVSAvoidpumping power requirement

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The patent employs a fiber amplifier that continuously amplifies the laser beam generated by the fiber laser. This continuous amplification process efficiently converts pump energy into output power, maintaining high overall system efficiency while achieving high power output levels.

Inventive Principle:

Principle #20Continuity of useful action

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 average power pulse amplification with improved beam quality and efficiency for non-linear converters, reducing costs and complexity while enhancing the operation of non-linear converters like optical parametric oscillators.

Implementation Method 1

Thulium-doped silica fibers and narrow spectral bandwidth Bragg gratings to achieve high efficiency and ease of alignment

Methodology Applied

Scientific EffectStimulated emission: Laser

Implementation Method 2

The fiber lasers utilize Bragg gratings to create a resonant cavity

Methodology Applied

Scientific EffectBragg diffraction: Bragg Diffraction

Data Source

PatentUS8194310B1All fiber pulse generator for pumping a non-linear converter

Publication Date: 2012.06.05 BAE SYSTEMS INFORMATION ANDELECTRONIC SYSTEMS INTEGRATION INC

AI summary

An all fiber mid-IR pulse generator is disclosed that may be used to drive an external non-linear converter. The generator comprises fiber laser oscillator and fiber amplifier elements wherein diode lasers are used to cladding pump the different fiber elements depending on different configurations of the pulse generator. Gain switching of the fiber lasers precludes the need for discrete devices such as Q-switches to generate pulses. The fiber laser and fiber amplifier elements are all fused together, along with fiber isolators and reflective gratings, so there is no free space coupling, and there are no optical elements except as may be needed to couple the output of the generator to a non-linear converter. The all fiber implementation has a single transverse mode at the lowest order mode of operation which results in a nearly diffraction limited output which causes non-linear converters to operate more efficiently. To further increase the efficiency of the non-linear converters the fiber laser oscillator has Bragg gratings with a narrow spectral bandwidth of less than 0.5 nanometers.