Phase-stabilized Ultrashort Laser Systems for Spectroscopy

Table of Contents

1 Introduction

1.1 Time-resolved spectroscopy

1.2 Optical frequency metrology with frequency combs

2 Ultra-broadband oscillators

2.1 Few-cycle Kerr-lens mode-locked Ti:sapphire oscillator

2.2 Chirped mirror technology for dispersion control

2.3 The carrier-envelope phase of a mode-locked oscillator

2.3.1 Measurement of the frequency comb parameters

2.3.2 CE phase stabilization by difference frequency generation

2.3.3 Control of the frequency comb parameters

2.3.4 CE phase stability characterization

2.4 Long-cavity chirped-pulse oscillators

2.4.1 Double-pass post-amplifier

2.5 Conclusions

3 Few-cycle chirped-pulse amplifier systems

3.1 CE phase-stabilized chirped-pulse amplifier system

3.1.1 Origins of CE phase noise of amplified pulses

3.2 Conclusions

4 Femtosecond enhancement cavities

4.1 Passive optical resonators for femtosecond pulses

4.1.1 Dispersion control

4.1.2 Electronic feedback techniques

4.2 Vacuum enhancement cavity at 10 MHz repetition rate

4.3 Conclusions

5 Applications

5.1 Spectroscopy experiments with frequency combs

5.2 High-order harmonic generation

5.2.1 High harmonic generation from surfaces

5.2.2 High-order harmonic generation in an enhancement cavity

5.3 Above-threshold ionization

5.4 Conclusions

6 Outlook

A Appendix

A.1 Origin of the frequency comb

A.2 Offset frequency dependence on group and phase velocity

Research Objectives and Core Topics

The work aims to develop and refine ultrafast laser sources capable of generating few-cycle pulses with a precisely controlled electric field waveform. This control is crucial for probing and manipulating fundamental light-matter interaction processes at the sub-femtosecond and attosecond timescales, enabling high-precision spectroscopy and the investigation of strong-field phenomena.

• Stabilization of carrier-envelope (CE) phase in ultra-broadband oscillators using monolithic difference frequency generation.
• Integration of phase-stabilized oscillators into chirped-pulse amplifier (CPA) systems to maintain phase control for high-energy pulses.
• Development of femtosecond enhancement cavities for high-repetition-rate nonlinear frequency conversion.
• Application of these laser sources to high-order harmonic generation (HHG) from surfaces and gas targets.
• Experimental study of above-threshold ionization (ATI) to demonstrate CE phase-dependent electron dynamics.

Excerpt from the Book

Summary of Chapters

1 Introduction: Provides an overview of light-matter interactions and introduces the motivation for phase-stabilized ultrashort laser systems in spectroscopy and metrology.

2 Ultra-broadband oscillators: Details the design of Kerr-lens mode-locked Ti:sapphire oscillators and presents a monolithic technique for CE phase stabilization via difference frequency generation.

3 Few-cycle chirped-pulse amplifier systems: Discusses the integration of phase-stabilized oscillators into amplifier chains and analyzes the noise sources that impact phase stability during amplification.

4 Femtosecond enhancement cavities: Explores the use of passive optical resonators to increase pulse energy and average power for applications like high-order harmonic generation at high repetition rates.

5 Applications: Examines practical implementations of the developed laser sources, including frequency comb spectroscopy, high-order harmonic generation from surfaces, and above-threshold ionization experiments.

6 Outlook: Summarizes the technological progress and discusses future potential for scaling pulse energy and extending spectroscopic capabilities to new spectral ranges.

Keywords

Ultrafast laser, Few-cycle pulses, Carrier-envelope phase, CE phase stabilization, Ti:sapphire oscillator, Frequency comb, Chirped-pulse amplification, Enhancement cavities, High-order harmonic generation, Above-threshold ionization, Dispersion control, Nonlinear optics, Spectroscopy, Attosecond physics, Femtochemistry.

Frequently Asked Questions

What is the primary objective of this research?

The research focuses on the generation and stabilization of few-cycle ultrashort laser pulses with a controlled carrier-envelope (CE) phase to enable high-precision time-resolved spectroscopy and strong-field physics.

Which laser system serves as the foundation for these experiments?

The work primarily utilizes mode-locked Ti:sapphire laser oscillators, which are known for their broad spectral bandwidth and suitability for generating ultrashort pulses.

What is the importance of the carrier-envelope (CE) phase?

In ultrashort pulses, the CE phase determines the exact position of the electric field oscillations relative to the pulse envelope, which is critical for steering and observing processes on sub-femtosecond timescales.

How is the CE phase stabilized?

The author introduces a monolithic approach using difference frequency generation (DFG) in a nonlinear crystal, which avoids the complexities and instability issues of traditional fiber-based f-to-2f interferometers.

What is the role of enhancement cavities?

Enhancement cavities are used to increase the pulse energy and peak intensity of the laser pulses while maintaining a high repetition rate, which is necessary for high-efficiency nonlinear processes like high-order harmonic generation.

What are the key themes of the application chapter?

The applications focus on high-resolution frequency comb spectroscopy, the generation of extreme ultraviolet (XUV) light through high-order harmonic generation, and the study of photoelectron dynamics via above-threshold ionization.

Why are solid surfaces explored for high-order harmonic generation (HHG)?

Solid targets offer higher particle density compared to gases, holding the potential for increased conversion efficiency and lower vacuum requirements in the experiment.

How does the author characterize the quality of the CE phase stabilization?

Stability is characterized through both "in-loop" and "out-of-loop" measurements, using techniques such as the Allan variance to determine the long-term drift and timing jitter of the pulses.