Interferometric autocorrelation in the ultraviolet utilizing spontaneous parametric down-conversion inside an...

Area of Science:

• Quantum Optics
• Ultrafast Laser Science
• Nonlinear Optics

Background:

• Autocorrelation is crucial for measuring ultrashort laser pulse durations.
• Existing methods like second-harmonic generation are difficult for ultraviolet (UV) pulses due to material absorption.
• A new approach is needed to characterize ultrashort UV laser pulses effectively.

Purpose of the Study:

• To develop a novel method for measuring ultrashort UV laser pulse durations.
• To overcome the limitations of traditional autocorrelation techniques in the UV regime.
• To demonstrate the first direct measurement of ultrashort UV pulses within a UV enhancement cavity.

Main Methods:

• Utilizing spontaneous parametric down-conversion (SPDC) to generate an autocorrelation signal in the infrared (IR).
• Leveraging nth-order emission from SPDC, which is proportional to the nth power of the UV intensity.
• Counting 2n down-converted photons to directly obtain the nth-order autocorrelation.

Main Results:

• Successfully generated an IR autocorrelation signal for UV pulses using SPDC.
• Demonstrated that counting down-converted photons directly yields the nth-order autocorrelation.
• Achieved the first direct measurement of ultrashort UV pulses circulating inside a UV enhancement cavity using this method.

Conclusions:

• Spontaneous parametric down-conversion provides a viable alternative for ultrashort UV pulse characterization.
• The developed method overcomes significant challenges associated with UV nonlinear optics.
• This technique opens new possibilities for studying and controlling ultrafast UV laser systems.