| Dettaglio Tesi |
| Studente: CONDIO STEFANO |
| Email Ateneo: stefano.condio@edu.unito.it |
| Anno accademico: 2019-20 |
| Iscritto alla Facoltà di: FISICA |
| Corso di studi: FISICA |
| Area disciplinare: SCIENZE FISICHE |
| Tipologia tesi: Laurea II livello |
| Lingua tesi: INGLESE |
| Titolo tesi: Realizzazione di un orologio a reticolo ottico con un diodo laser amplificato |
| Titolo tesi inglese: Optical lattice clock with an amplified laser diode |
| Titolo tesi in altra lingua: n.d. |
Abstract tesi:
Optical lattice clocks occupy a very important position in metrological research. Diffused worldwide, they are a strong candidate for a future redefinition of the second of
the International System of Units (SI) and thanks to their extremely small fractional
uncertainty about 10−18 they are involved in fundamental physics experiments, for example in the field of general relativity. In a optical clock, the lattice is used to trap
ultracold atoms and it is realized with a retro-reflected laser tuned on magic wavelength to reduce perturbations on the clock transition. An optical lattice is generated
usually starting by a titanium:sapphire laser: its main qualities are high output power
and narrow linewidth, but it is delicate and difficult to use so its application in new
kinds of atomic clocks, such as transportable or spacial, is not strongly recommended.
Replacing it with an amplified laser diode would be preferable because these instruments are better for cost, reliability, size and weight, so suitable for applications out of
laboratory, but at the same time present the problem of spectral purity as they have
a not negligible amplified spontaneous emission (ASE): this phenomenon produces a
broad spectrum detuned from magic wavelength inducing a perturbation on the clock
transition. In my thesis I investigated experimentally the possibility to generate an
optical lattice starting from an amplified laser diode emitting at 759.35 nm, ytterbium
magic wavelength, and I applied the laser system that I developed on the atomic clock
IT-Yb1 at Istituto Nazionale di Ricerca Metrologica (INRiM) located in Torino. The
target of this work is to achieve fractional uncertainty due to ASE below 10−18, making the performances of the two different lasers sources equivalent. First, I calculated
the theoretical model of the light shift induced by the lattice on the clock transition
between ytterbium atomic states 1S0 →3 P0, comparing it with experimental results
and I applied it to estimate ASE contribution to lattice shift. In the experimental part
of this work I realized an optical system to study amplified laser diode emission and
manipulate laser beam to obtain a good lattice from this laser source, filtering ASE
with a volume Bragg grating and controlling power with an acousto optic modulator.
Moreover I studied ASE spectral distribution in different conditions and its interaction
with optical elements. Next studies foresee to measure experimentally with IT-Yb1
the shift induced by the laser system that I realized to calculate its uncertainty contribution and compare this result with the one obtained with a titanium:sapphire laser.
This work will be useful to the development of compact or transportable atomic clocks
based exclusively on semiconductor lasers with applications in the generation of optical
timescales, travelling optical standards and the measurements of Earth gravitational
redshift. |
Abstract altra lingua:
Optical lattice clocks occupy a very important position in metrological research. Diffused worldwide, they are a strong candidate for a future redefinition of the second of
the International System of Units (SI) and thanks to their extremely small fractional
uncertainty about 10−18 they are involved in fundamental physics experiments, for example in the field of general relativity. In a optical clock, the lattice is used to trap
ultracold atoms and it is realized with a retro-reflected laser tuned on magic wavelength to reduce perturbations on the clock transition. An optical lattice is generated
usually starting by a titanium:sapphire laser: its main qualities are high output power
and narrow linewidth, but it is delicate and difficult to use so its application in new
kinds of atomic clocks, such as transportable or spacial, is not strongly recommended.
Replacing it with an amplified laser diode would be preferable because these instruments are better for cost, reliability, size and weight, so suitable for applications out of
laboratory, but at the same time present the problem of spectral purity as they have
a not negligible amplified spontaneous emission (ASE): this phenomenon produces a
broad spectrum detuned from magic wavelength inducing a perturbation on the clock
transition. In my thesis I investigated experimentally the possibility to generate an
optical lattice starting from an amplified laser diode emitting at 759.35 nm, ytterbium
magic wavelength, and I applied the laser system that I developed on the atomic clock
IT-Yb1 at Istituto Nazionale di Ricerca Metrologica (INRiM) located in Torino. The
target of this work is to achieve fractional uncertainty due to ASE below 10−18, making the performances of the two different lasers sources equivalent. First, I calculated
the theoretical model of the light shift induced by the lattice on the clock transition
between ytterbium atomic states 1S0 →3 P0, comparing it with experimental results
and I applied it to estimate ASE contribution to lattice shift. In the experimental part
of this work I realized an optical system to study amplified laser diode emission and
manipulate laser beam to obtain a good lattice from this laser source, filtering ASE
with a volume Bragg grating and controlling power with an acousto optic modulator.
Moreover I studied ASE spectral distribution in different conditions and its interaction
with optical elements. Next studies foresee to measure experimentally with IT-Yb1
the shift induced by the laser system that I realized to calculate its uncertainty contribution and compare this result with the one obtained with a titanium:sapphire laser.
This work will be useful to the development of compact or transportable atomic clocks
based exclusively on semiconductor lasers with applications in the generation of optical
timescales, travelling optical standards and the measurements of Earth gravitational
redshift.
|
| Relatore: Elena Botta |
| Eventuali note: n.d. |
| Data consegna on line della tesi: 02/04/2021 |
