Keywords

Chirped Pulse Amplifier, Fe:ZnSe, Optics, Laser, Optical Parametric Amplifier, MWIR, Infrared

Abstract

This dissertation details the development of the world’s first cryogenically cooled Fe:ZnSe-based chirped pulse amplifier, a mid-wave infrared source for strong-field physics experimentation. The long upper-state lifetime provided by cryogenically cooling the Fe:ZnSe gain medium allows free-running, diode-pumped Er:YAG lasers to be used as pump lasers. The amplifier is seeded by a novel two-stage optical parametric amplifier pumped at 1 μm, which is potentially carrier-envelope phase-stable. The system is capable of producing 247-fs pulses at 333 Hz and 4.6 mJ with a center wavelength of 4.07 μm, although exact characteristics vary for different repetition rates and arrangements. The spectral bandwidth avoids strong atmospheric CO2 absorption centered around 4.3 μm, allowing operation in ambient air with good beam quality. The laser is simple, stable, reliable, and boasts a high repetition rate and average power compared to other systems. By focusing the 18-GW beam in air, harmonics up to the ninth order were observed indicating its potential for use in strong-field experimentation. Few-cycle pulses were generated by passing the beam, at a repetition rate of 400 Hz, through a large-diameter gas-filled hollow-core fiber followed by dispersion compensating bulk CaF2. A krypton-filled fiber at 370 kPa yielded 1.14-mJ, 42-fs pulses centered at 4.07-μm, while an oxygen-filled fiber at 310 kPa delivered 0.78-mJ, 39-fs pulses spanning 3 to 5.5 μm. This work is a step toward a high repetition rate mid-wave infrared driver of isolated attosecond, keV-level, X-ray pulses. Fe:ZnSe is a unique gain medium with potential to become a disruptive technology across a variety of fields, especially in strong-field science, in which many physical phenomena are enhanced at longer wavelengths.

Completion Date

2024

Semester

Summer

Committee Chair

Chang, Zenghu

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Physics

Degree Program

Physics Ph.D.

Format

application/pdf

Release Date

8-15-2024

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

Campus Location

Orlando (Main) Campus

Accessibility Status

Meets minimum standards for ETDs/HUTs

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