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Carrier-envelope-phase insensitivity in high-order harmonic generation driven by few-cycle laser pulses
Optics Express
|September 15, 2015
Summary
High-order harmonic generation shows self-stabilization of spectral phase, making it insensitive to driving laser intensity variations. This stability enables robust attosecond pulse generation, crucial for advanced ultrafast science applications.
Area of Science:
- * Quantum Optics and Attosecond Science
- * Nonlinear Optics and Laser Physics
Background:
- * High-order harmonic generation (HHG) is a key process for producing extreme ultraviolet (XUV) and soft X-ray radiation.
- * The spectral phase of HHG is critical for attosecond pulse generation but is typically sensitive to driving laser parameters.
- * Controlling the carrier-envelope phase (CEP) of ultrashort driving lasers is challenging yet vital for precise HHG control.
Purpose of the Study:
- * To investigate the self-stabilization of the relative spectral phase in high-order harmonic emission.
- * To demonstrate the robustness of harmonic spectra against driving field intensity and CEP variations.
- * To confirm phase locking in attosecond pulse trains generated under these conditions.
Main Methods:
- * Experimental generation of high-order harmonics using sub-two-cycle and few-cycle driving laser fields.
- * Theoretical modeling to analyze phase matching in macroscopic media and the intensity dependence of intrinsic harmonic phases.
- * Spectroscopic analysis of harmonic emission and characterization of attosecond pulse trains.
Main Results:
- * Evidence of self-stabilization of the relative spectral phase of high-order harmonic emission.
- * Demonstration that phase matching near the laser focus compensates for intensity-dependent intrinsic phase variations.
- * Experimental and theoretical confirmation of insensitivity of harmonic spectra to driving field intensity and CEP fluctuations.
- * Observation of phase locking in associated attosecond pulse trains against CEP changes.
Conclusions:
- * Macroscopic phase matching near the laser focus enables self-stabilization of the spectral phase of high-order harmonics.
- * This self-stabilization leads to robust harmonic generation insensitive to driving laser intensity and CEP variations.
- * The findings pave the way for reliable generation of attosecond pulses for ultrafast science applications.
