Passively mode locked Raman laser

We report on the observation of a novel mode locked optical comb generated at the Raman offset (Raman comb) in an optically pumped crystalline whispering gallery mode resonator. Mode locking is confirmed via measurement of the radio-frequency beat note produced by the optical comb on a fast photodiode. Neither the conventional Kerr comb nor hyper-parametric oscillation is observed when the Raman comb is present

An apparatus for the electrodynamic containment of charged macroparticles

The dynamic moition of the ions contained in the trapped (199)Hg+ frequency standard contributes to the stability of the standard. In order to study these dynamics, a macroscopic analog of the (199)Hg+ trap is constructed. Containment of micron-sized particles in this trap allows direct visual observation of the particles' motion. Influenced by the confining fields and their own Coulomb repulsion, the particles can form stable arrays

Computer simulations of ions in radio-frequency traps

The motion of ions in a trapped-ion frequency standard affects the stability of the standard. In order to study the motion and structures of large ion clouds in a radio-frequency (RF) trap, a computer simulation of the system that incorporates the effect of thermal excitation of the ions was developed. Results are presented from the simulation for cloud sizes up to 512 ions, emphasizing cloud structures in the low-temperature regime

Transient Regime of Kerr Frequency Comb Formation

Temporal growth of an optical Kerr frequency comb generated in a microresonator is studied both experimentally and numerically. We find that the comb emerges from vacuum fluctuations of the electromagnetic field on timescales significantly exceeding the ringdown time of the resonator modes. The frequency harmonics of the comb spread starting from the optically pumped mode if the microresonator is characterized with anomalous group velocity dispersion. The harmonics have different growth rates resulting from sequential four-wave mixing process that explains intrinsic modelocking of the comb.Comment: 4 pages, 5 figure

Hard and Soft Excitation Regimes of Kerr Frequency Combs

We theoretically study the stability conditions and excitation regimes of hyper-parametric oscillation and Kerr frequency comb generation in continuously pumped nonlinear optical resonators possessing anomalous group velocity dispersion. We show that both hard and soft excitation regimes are possible in the resonators. Selection between the regimes is achieved via change in the parameters of the pumping light.Comment: 4 pages, 7 figure

Effectiveness Treatment ERP on Obsessive – Compulsive Disorder (OCD)

This study is aimed to consider the effectiveness of exposure therapy and Exposure Response Prevention (ERP) on decrease of symptoms of obsessive - compulsive disorder is. The research method was quasi-experimental and its design was pre-test and post-test with control group. The statistical population of this study was all patients with obsessive-compulsive disorder (both male and female) referring to therapy centers of Maragheh city that a sample of 30 subjects was chosen by available sampling method and then they were replaced in experimental (therapy) group and control group randomly and answered to Maudsley Obsessive-Compulsive Inventory (MOCI). The findings indicated that the experimental group's average score in obsessive-compulsive symptoms was 14/46 in pre-test and 7/67 in post-test. As well as, in control group, the mean score of obsessive - compulsive symptoms in pre-test was 14/66 and 11/93 in post-test. Thus, it could be concluded that the reduction of scores in post-test of experimental group was accompanied with the decrease of symptoms of obsessive - compulsive disorder in experimental group