Giving to CREOL
CREOL, The College of Optics & Photonics

Final Examination of Nathan Bodnar for the Degree of Master of Science in Optics

Tuesday, November 13, 2012 1:00 PM to 3:00 PM
CREOL Room 102

Dissertation Title:
Phase-locking stability of a quasi-single-cycle pulse

There is increasing interest in the generation of very short laser pulses, even down to attosecond (10-18 s) durations. Laser systems with femtosecond pulse durations are needed for these applications. For many of these applications, positioning of the maximum electric field within the pulse envelope can affect the outcome. The peak of the electric field relative to the peak of the pulse is called the Carrier Envelope Phase (CEP). Controlling the position of the electric field becomes more important when pulse duration approaches single-cycle.

This thesis focuses on the stabilization of a quasi-single-cycle laser facility. Improvements to this already-established laser facility, HERACLES (High Energy, Repetition rate Adjustable, Carrier-Locked-to-Envelope System) described in this thesis include a stabilized pump line and the improvement in CEP stabilization electronics.
HERACLES is built upon an Optical Parametric Chirped Pulse Amplification (OPCPA) architecture. This architecture uses Optical Parametric Amplification (OPA) as the gain material to increase the output energy of the system. OPA relies on a nonlinear process to generate high gain (106) with ultra-wide bandwidth. Instabilities in the OPA driving pump energy can create dynamically fluctuations in the final OPCPA output energy. To reduce these fluctuations two key upgrades were implemented on the pump beam. Both were major improvements in the stability. Firstly, an improved regenerative amplifier design reduced beam pointing fluctuations. Secondly, the addition of a pump monitoring system with feedback-control eliminated long-term power drifts. Both enhanced the OPA pulse-to-pulse and long-term stability.

To improve the stability in measuring CEP drifts, modification of the feedback electronics was needed. The modification consisted of integrating noise reduction electronics. This novel noise reducer uses a similar process to a super-heterodyne receiver. The noise reducer resulted in 60 dB reduction of out-of-band noise. This led to increased signal quality with cleaner amplification of weaker signals. The enhanced signal quality led to more reliable long-term locking. The synthetically increased signal-to-noise ratio allows locking of the CEP frequency below the typically requirements. This integration allows relaxed constraints on the laser systems.

The optics and electronics of a high-power, quasi-single cycle laser facility were improved. This thesis included the stabilization of the pump line and the stabilization of the CEP. This work allows for new long-duration experiments.

Major:  Optics

Educational Career:
BS: 2010,  University of Central Florida
Committee in Charge:
Dr. Martin Richardson (Chair)
Dr. Zhenghu Chang
Dr. Peter Delfyett

Approved for distribution by Dr. Martin Richardson, Committee Chair, on 11/06/2012.
The public is welcome to attend.

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