726 research outputs found
Synchronization and Characterization of an Ultra-Short Laser for Photoemission and Electron-Beam Diagnostics Studies at a Radio Frequency Photoinjector
A commercially-available titanium-sapphire laser system has recently been
installed at the Fermilab A0 photoinjector laboratory in support of
photoemission and electron beam diagnostics studies. The laser system is
synchronized to both the 1.3-GHz master oscillator and a 1-Hz signal use to
trigger the radiofrequency system and instrumentation acquisition. The
synchronization scheme and performance are detailed. Long-term temporal and
intensity drifts are identified and actively suppressed to within 1 ps and
1.5%, respectively. Measurement and optimization of the laser's temporal
profile are accomplished using frequency-resolved optical gating.Comment: 16 pages, 17 figures, Preprint submitted to Elsevie
Ultra-Low Noise Microwave Extraction from Fiber-Based Optical Frequency Comb
In this letter, we report on all-optical fiber approach to the generation of
ultra-low noise microwave signals. We make use of two erbium fiber mode-locked
lasers phase locked to a common ultra-stable laser source to generate an 11.55
GHz signal with an unprecedented relative phase noise of -111 dBc/Hz at 1 Hz
from the carrier.The residual frequency instability of the microwave signals
derived from the two optical frequency combs is below 2.3 10^(-16) at 1s and
about 4 10^(-19) at 6.5 10^(4)s (in 5 Hz bandwidth, three days continuous
operation).Comment: 12 pages, 3 figure
Low Noise, High Repetition Rate Semiconductor-based Mode-locked Lasers For Signal Processing And Coherent Communications
This dissertation details work on high repetition rate semiconductor mode-locked lasers. The qualities of stable pulse trains and stable optical frequency content are the focus of the work performed. First, applications of such lasers are reviewed with particular attention to applications only realizable with laser performance such as presented in this dissertation. Sources of timing jitter are also reviewed, as are techniques by which the timing jitter of a 10 GHz optical pulse train may be measured. Experimental results begin with an exploration of the consequences on the timing and amplitude jitter of the phase noise of an RF source used for mode-locking. These results lead to an ultralow timing jitter source, with 30 fs of timing jitter (1 Hz to 5 GHz, extrapolated). The focus of the work then shifts to generating a stabilized optical frequency comb. The first technique to generating the frequency comb is through optical injection. It is shown that not only can injection locking stabilize a mode-locked laser to the injection seed, but linewidth narrowing, timing jitter reduction and suppression of superfluous optical supermodes of a harmonically mode-locked laser also result. A scheme by which optical injection locking can be maintained long term is also proposed. Results on using an intracavity etalon for supermode suppression and optical frequency stabilization then follow. An etalon-based actively mode-locked laser is shown to have a timing jitter of only 20 fs (1Hz-5 GHz, extrapolated), optical linewidths below 10 kHz and optical frequency instabilities less than 400 kHz. By adding dispersion compensating fiber, the optical spectrum was broadened to 2 THz and 800 fs duration pulses were obtained. By using the etalon-based actively mode-locked laser as a basis, a completely self-contained frequency stabilized coupled optoelectronic oscillator was built and characterized. By simultaneously stabilizing the optical frequencies and the pulse repetition rate to the etalon, a 10 GHz comb source centered at 1550 nm was realized. This system maintains the high quality performance of the actively mode-locked laser while significantly reducing the size weight and power consumption of the system. This system also has the potential for outperforming the actively mode-locked laser by increasing the finesse and stability of the intracavity etalon. The final chapter of this dissertation outlines the future work on the etalon-based coupled optoelectronic oscillator, including the incorporation of a higher finesse, more stable etalon and active phase noise suppression of the RF signal. Two appendices give details on phase noise measurements that incorporate carrier suppression and the noise model for the coupled optoelectronic oscillator
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