3 research outputs found
33 Femtosecond Yb-doped optical frequency comb for frequency metrology applications
Ankara : The Department of Physics and the Graduate School of Engineering and Science of Bilkent University, 2013.Thesis (Master's) -- Bilkent University, 2013.Includes bibliographical references leaves 76-87.Optical frequency combs have enabled many applications (high precision spectroscopy,
table-top optical frequency metrology, optical atomic clocks, etc.), received
considerable attention and a Nobel Prize. In this thesis, the development
of a stabilized Yb-doped femtosecond optical frequency comb is presented. As a
starting point in the development of the frequency comb, a new type of fiber laser
has been designed using numerical simulations and realized experimentally. The
developed laser is able to produce pulses that can be compressed to 33 fs without
higher-order dispersion compensation. After realization of the laser, a new type
of fiber amplifier has been developed to be used for supercontinuum generation.
The amplifier produces 6.8 nJ pulses that can be compressed to 36 fs without
higher-order dispersion compensation. The dynamics of supercontinuum generation
have been studied by developing a separate simulation program which solves
the generalized nonlinear Schr¨odinger equation. Using the simulation results, appropriate
photonic crystal fiber was chosen and octave-spanning supercontinuum
was generated. Carrier-envelope-offset frequency of the laser has been obtained
by building an f-2f interferometer. Repetition rate and carrier-envelope offset
frequency of the laser have been locked to Cs atomic clock using electronic feedback
circuits, resulting in a fully stabilized optical frequency comb. The noise
performance and stability of the system have been characterized. Absolute frequency
measurement of an Nd:YAG laser, which was stabilized using iodine gas,
has been performed using the developed optical frequency comb.Şenel, ÇağrıM.S
Guidelines for developing optical clocks with fractional frequency uncertainty
There has been tremendous progress in the performance of optical frequency
standards since the first proposals to carry out precision spectroscopy on
trapped, single ions in the 1970s. The estimated fractional frequency
uncertainty of today's leading optical standards is currently in the
range, approximately two orders of magnitude better than that of the best
caesium primary frequency standards. This exceptional accuracy and stability is
resulting in a growing number of research groups developing optical clocks.
While good review papers covering the topic already exist, more practical
guidelines are needed as a complement. The purpose of this document is
therefore to provide technical guidance for researchers starting in the field
of optical clocks. The target audience includes national metrology institutes
(NMIs) wanting to set up optical clocks (or subsystems thereof) and PhD
students and postdocs entering the field. Another potential audience is
academic groups with experience in atomic physics and atom or ion trapping, but
with less experience of time and frequency metrology and optical clock
requirements. These guidelines have arisen from the scope of the EMPIR project
"Optical clocks with uncertainty" (OC18). Therefore, the
examples are from European laboratories even though similar work is carried out
all over the world. The goal of OC18 was to push the development of optical
clocks by improving each of the necessary subsystems: ultrastable lasers,
neutral-atom and single-ion traps, and interrogation techniques. This document
shares the knowledge acquired by the OC18 project consortium and gives
practical guidance on each of these aspects