|
|
Laser with Narrow Spectral Linewidth for Metrology of Length
Pham, Minh Tuan ; Smrž, Martin (oponent) ; Peterka,, Pavel (oponent) ; Číp, Ondřej (vedoucí práce)
The thesis deals with stabilising a diode laser operating at a wavelength of 729 nm, which is used for high-resolution spectroscopy and interacting with captured and cooled calcium ions. Interaction with the ion requires an extremely narrow spectral linewidth for the excitation laser. The work explains essential procedures and methods leading to the operation of a laser with a spectral linewidth in the order of Hz or less. The central part of the work is to design and put together an optical assembly for this laser with the necessary electro-optical elements. The main emphasis is placed on laser frequency stabilisation techniques using external references, their theoretical description and implementation are also a part of this work. The first chosen approach to narrowing the spectral linewidth is locking the optical frequency of the laser to a selected component of the optical frequency comb using electronic phase locks. Spectral noise measurements were performed using a two-beam interferometer with unbalanced arms. The achieved noise suppression results for the locked laser were then compared with the free-running laser mode. Another approach is to lock the spectral line of the laser to a very narrow line of a high-quality optical resonator. With this method, I achieved a laser with a very narrow spectral line (in the order of tens of Hz), however, with short-term stability. The next step was the construction and use of the "transfer oscillator" technique, which provided additional compensation for the unwanted drift of the resonance mode of the optical resonator and thereby ensured the long-term stability of the entire system. The laser stabilised in this way at 729 nm was tested in spectroscopy on the forbidden transition of the Doppler cooled calcium ion.
|
host ::
RSS.