Picosecond Optical Parametric Generator Seed Amplification

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Solution Overview

Problem

Current tunable picosecond lasers with low-repetition-rate optical parametric generators face limitations in parametric gain due to short interaction times, resulting in low-output pulse energy and broad spectral width, and are sensitive to mechanical disturbances, making them unreliable for high-resolution spectroscopic applications.

Innovation Solution

A picosecond optical parametric generator system with a spatial filter and a pulsed dye amplifier stage, using a high-power seed laser and a β-BBO crystal, which significantly increases output beam quality and allows for enhanced coarse and fine wavelength tuning, enabling higher energy output and robust operation at 10 Hz repetition rate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a low-repetition-rate picosecond optical parametric generator is used, then the interaction time is short, but this results in limited parametric gain and low output pulse energy

Engineering Contradiction:

Improveinteraction timeVSAvoidoutput pulse energy

Core Design Contradiction:

SpeedVSQuantity of substance

Solution Approach 1:

The patent uses a high-energy seed laser to pre-amplify the signal before it enters the optical parametric generator. This preliminary action of seed amplification allows the subsequent single-pass interaction to produce higher output energy despite the short interaction time inherent in low-repetition-rate picosecond operation.

Inventive Principle:

Principle #10Preliminary action

2Speed

If a low-repetition-rate picosecond optical parametric generator is used, then the interaction time is short, but this results in broad spectral width

Engineering Contradiction:

Improveinteraction timeVSAvoidspectral width

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The high-energy seed laser provides a narrow spectral width before the parametric generation process. This preliminary spectral definition is preserved through the single-pass interaction, allowing the system to achieve narrow spectral width despite the short interaction time.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If a distributed-feedback dye laser is used to provide nearly transform-limited pulses, then the pulse quality is high, but the system becomes overly sensitive to mechanical disturbances

Engineering Contradiction:

Improvepulse qualityVSAvoidsensitivity to mechanical disturbances

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent replaces the mechanically sensitive distributed-feedback dye laser with a more robust seed laser system that is less sensitive to mechanical disturbances. This substitution maintains the ability to produce nearly transform-limited pulses while significantly improving system reliability and reducing sensitivity to vibration and temperature changes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Device complexity

If prior art tunable picosecond optical parametric amplifiers are used, then the system is simpler, but the output pulse energy is low

Engineering Contradiction:

Improvesystem complexityVSAvoidoutput pulse energy

Core Design Contradiction:

Device complexityVSQuantity of substance

Solution Approach 1:

The patent introduces a preliminary amplification stage using a high-energy seed laser before the optical parametric generation. This additional step, while increasing system complexity, enables significantly higher output pulse energy by ensuring that the parametric process operates with amplified input energy from the outset.

Inventive Principle:

Principle #10Preliminary 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 produces nearly transform-limited picosecond pulses with higher output energy and improved beam quality, enabling more robust and versatile applications in spectroscopy, including high-resolution molecular analysis and efficient nonlinear processes.

Implementation Method 1

A picosecond optical parametric generator system with a spatial filter and a pulsed dye amplifier stage, using a high-power seed laser and a β-BBO crystal

Methodology Applied

Scientific EffectOptical parametric amplification:

Implementation Method 2

A picosecond optical parametric generator system with a spatial filter and a pulsed dye amplifier stage

Methodology Applied

Scientific EffectSpatial filtering: Spatial Filter

Implementation Method 3

a pulsed dye amplifier stage having an input and first and second dye cells

Methodology Applied

Scientific EffectOptical amplification:

Data Source

PatentUS11177622B1Nearly transform-limited, low-repetition-rate, picosecond optical parametric generator

Publication Date: 2021.11.16 THE GOVERNMENT OF THE UNITED STATES AS REPRESENTED BY THE SECRETARY OF THE AIR FORCE

AI summary

A low-repetition-rate (10-Hz), picosecond (ps) optical parametric generator (OPG) system produces higher energy output levels in a more robust and reliable system than previously available. A picosecond OPG stage is seeded at an idler wavelength with a high-power diode laser and its output at ˜566 nm is amplified in a pulsed dye amplifier (PDA) stage having two dye cells, resulting in signal enhancement by more than three orders of magnitude. The nearly transform-limited beam at ˜566 nm has a pulse width of ˜170 ps with an overall output of ˜2.3 mJ/pulse. A spatial filter between the OPG and PDA stages and a pinhole between the two dye cells improve high output beam quality and enhances coarse and fine wavelength tuning capability.