The quantum properties of optical frequency combs have been the focus of several research works in recent years. Investigating the quantum correlations between the spectral components of the combs is of fundamental interest because it allows for a better understanding of light-matter interactions, but also of technological interest as it wold permits the implementation of quantum communication networks. In this communication, we present some of our latest advances in this field.
An experimental study of the variation of quality factor (Q-factor) of mm-size whispering-gallery mode (WGM) resonators manufactured with fluoride crystals as a function of surface roughness is proposed. Q-factors of the order of 1 billion are measured at 1550 nm. The experimental procedure needs repeated polishing steps, after which the surface roughness is measured by quantitative phase imaging, based on a white-light phase-shifting interferometry approach, while the Q-factors are determined using the cavity-ring-down method. This process allows us to reach an explicit curve linking the Q-factor of the disk-resonator to the surface roughness of the rim.
The variations of Q-factor as a function of surface roughness is universal, in the sense that it is globally independent of the bulk material under consideration. We used a white-light interferometer to investigate the dependency of Q-factors considering three different difluoride crystals as bulk materials; in all cases, we have found that a billion Q-factors at 1550 nm are achieved when the rms surface roughness has a nanometer order of magnitude.
We have also compared our experimental data with theoretical estimations. This comparison enabled us to highlight a mismatch, which can be explained by the many physical constraints imposed by the mechanical grinding and polishing protocol. We expect that our work will contribute to a better understanding of the Q-factor limitations for mm-size WGM resonators, which are finding applications in a broad range of areas.
In this communication, present some of our latest results related to Kerr optical frequency comb generation. We investigate the conditions under which the energy conversion from the lightwave to the microwave spectral ranges is optimized. Our main finding is that the optimal regime features a pump-to-sidemode ratio smaller than 4 dB, corresponding to a conversion efficiency better than 40 %.
Whispering gallery mode resonators have been the focus of many research works in recent years. They allow to study the light-matter interactions induced by the confinement of photons in nonlinear media. In particular, Brillouin Raman and Kerr nonlinearities excite the resonator at the lattice, molecular and electronic scale. This difference in spatial scales give to whispering gallery-mode resonators the potential to be central photonic components in microwave photonics, quantum optics and optoelectronics. We discuss in this communication some of the key challenges that have to be met for the understanding of Kerr, Raman and Brillouin interactions that can take place in these resonators.
We report an investigation on optoelectronic oscillators based on a combination of a fiber delay line and a whispering gallery mode resonator. We analyze the dynamical processes which are key for the understanding of the spectral purity of these oscillators. We therefore show how combining both optical elements leads to significant improvement of the spectral purity of the oscillator, as it leads to a spurious rejection rate higher than 50 dB.
We report and discuss some of the latest advances in Kerr optical frequency comb generation. We principally focus on widely tunable primary combs, and on the role played by the eigenmode family of the modes of interest. Our work shows that there is a giant dispersion shift between the various radial families of modes, and that we can use them to generate primary combs with significantly different intermodal spacings.
We theoretically and experimentally investigate some effects related to the Kerr optical frequency comb generation, using a millimeter-size magnesium fluoride ultrahigh quality disk resonator. We show that the Kerr comb tunability can be extremely wide in the Turing pattern (or primary comb) regime, with an intermodal frequency that can be tuned from 4 to 229 multiple free spectral ranges (corresponding to a frequency spacing ranging from 24 GHz to 1.35 THz). We also discuss the role played by thermal locking while pumping the resonator, as well as the effect of modal crossing when broadband combs are generated.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.