The mid-infrared (MIR) system presented in the thesis is based on a sub-100-fs erbium-doped fiber laser operating at 1.55 µm. The output of the laser is split in two, each arm
seeding an erbium-doped fiber amplifier. The output of the first amplifier is sent to a
grating-based stretcher to be stretched to 50 ps before seeding the optical parametric
chirped-pulse amplifier (OPCPA). The output of the second amplifier is coupled to a
highly nonlinear fiber to generate the 1 µm needed to seed the a neodymium-doped
yttrium lithium fluoride (Nd:YLF) system. This work represents the first time this
synchronization scheme is used, and the timing jitter between the two arms at the OPCPA
is reduced to 333 fs.
The pump laser for the OPCPA is a regenerative amplifier producing 1.6 W followed
by a double-pass amplifier, for a final output power of 2.5 W at 1 kHz. Etalons were
inserted into the cavity of the regenerative amplifier to stretch the pulses to 50 ps
The OPCPA consists of two potassium titanyl arsenate crystals in a noncollinear
configuration. With three passes, the gain is 3.8 · 10
6
. Using a grating compressor, the
pulse duration is reduced to 140 fs, with a power of 300 mW. Because of the reduction of
the timing jitter, the amplitude stability is 1 %, which is a great improvement compare
to existing systems.
To generate ultrafast light in the MIR, an optical parametric amplifier is used, pumped
ii
by the output of the OPCPA and seeded with its 3-µm idler. Two crystals were tested,
both in a single-pass configuration. For the first crystal, a 4-mm thick silver thiogallate,
an efficiency of 7.4 % was reached, with 8.76 mW in the signal and 7.2 mW in the idler.
For the second crystal, a 2-mm thick lithium gallium selenide, the efficiency was higher,
reaching 10.8 %. The power for the signal was 11.5 mW, and for the idler, 11.11 mW.
Using this new scheme, energies on par with current systems are achieved with much
higher efficiencies.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/35927 |
| Date | 09 August 2013 |
| Creators | Pelletier, Etienne |
| Contributors | Miller, R. J. Dwayne |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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