Coherence properties of amplified slow light by four-wave mixing.

We present an experimental study of the coherence properties of amplified slow light by four-wave mixing (FWM) in a three-level electromagnetically induced transparency (EIT) system driven by one additional pump field. High energy gain (up to 19) is obtained with a weak pump field (a few mW/cm2) using optically dense cold atomic gases. A large fraction of the amplified light is found to be phase incoherent to the input signal field. The dependence of the incoherent fraction on pump field intensity and detuning and the control field intensity is systematically studied. With the classical input pulses, our results support a recent theoretical study by Lauk et al. [Phys. Rev. A88, 013823 (2013)], showing that the noise resulting from the atomic dipole fluctuations associated with spontaneous decay is significant in the high gain regime. This effect has to be taken into consideration in EIT-based applications in the presence of FWM.

Chaotic oscillations associated with the breakup of polarization entangled coherent states in a microchip solid-state laser.

We demonstrate the breakup of spatial-polarization entangled lasing patterns, which possess vector phase singularities, and the resultant dynamic instabilities featuring chaotic oscillations. The frequency splitting between a pair of Ince-Gauss (IG) lasing modes, originally forming a coherent entanglement state, and a self-excited additional nonorthogonal IG mode through a new class of transverse effect of self-injection pattern seeding, is shown to result in modal-interference-induced modulation at the beat frequency, leading to chaotic oscillations.

Low-light-level cross-phase modulation with double slow light pulses.

We report on the first experimental demonstration of low-light-level cross-phase modulation (XPM) with double slow light pulses based on the double electromagnetically induced transparency (EIT) in cold cesium atoms. The double EIT is implemented with two control fields and two weak fields that drive populations prepared in the two doubly spin-polarized states. Group velocity matching can be obtained by tuning the intensity of either of the control fields. The XPM is based on the asymmetric M-type five-level system formed by the two sets of EIT. Enhancement in the XPM by group velocity matching is observed. Our work advances studies of low-light-level nonlinear optics based on double slow light pulses.

Rounded Insertion Technique for Cochlear Implantation Surgery to Treat Cystic Inner Ear Malformation.

OBJECTIVE: This article outlines the advantages and applicability of the rounded insertion technique of cochlear implants in patients with cystic inner ear malformation. This technique enables the insertion of the maximum number of electrodes and prevents the unwanted entry of electrodes into the internal auditory canal. METHODS: We conducted a retrospective chart review of consecutive patients with cochlear hypoplasia (CH) and/or common cavity (CC) who underwent CI (cochlear implantation) via rounded insertion technique. The position of the electrode array in each patient was confirmed postoperatively via X-ray, and the number of functional electrodes was confirmed during the mapping process. RESULTS: This study included five male and two female patients (median age: 3 years; age range: 2-7 years). Among the seven patients, four received a cochlear implant on the right side, one on the left side, and two bilaterally. Of the nine ears, six were cases of CH, and three were CC. All cochlear implant surgeries via rounded insertion technique were completed without complications. The maximum number of electrode contacts with fair function in the cystic cochlea was confirmed via postoperative X-ray and the subsequent mapping process. CONCLUSION: This consecutive series of patients demonstrated the safety and reliability of rounded insertion technique for CI in patients with CH and/or CC. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:2229-2233, 2020.

Experimental Observations of Dual-Polarization Oscillations in Laser-Diode-Pumped Wide-Aperture Thin-Slice Nd:GdVO(4) Lasers.

Dual-polarization oscillations (DPO) on different transitions have been observed for the first time in a mirror-coated thin-slice Nd:GdVO(4) laser possessing a large fluorescence anisotropy with laser-diode (LD) pumping. Oscillation spectra, input-output characteristics, pump-dependent pattern formations and noise power spectra are studied experimentally. Simultaneous oscillations of orthogonally-polarized different (higher-order) transverse modes and the resultant violation of inherent antiphase dynamics in multimode lasers have been demonstrated. The experimental results have been explained in terms of the reduced three-dimensional cross-saturation of population inversions among orthogonally-polarized modes peculiar to LD-pumped wide-aperture anisotropic lasers, in which a pumped area is larger than a lasing beam diameter.

Chaos synchronization among orthogonally polarized emissions in a dual-polarization laser.

We report on the experimental observations of chaos synchronizations among orthogonally polarized emissions in a dual-polarization laser. With a three-mode scheme with a single mode in one polarization and two modes in orthogonal polarizations, synchronization was achieved by the cross-saturation dynamics of population inversions when one of the dual-polarized emissions was subjected to external perturbations, i.e., self-mixing modulation or optical fiber feedback. In-phase synchronization or lag synchronization among orthogonally polarized emissions was achieved depending on the degree of cross saturation in the self-mixing modulation. Synchronization of random bursting was observed in the fiber feedback, in which two chaotic-spiking modes in one polarization with anticorrelated intensity variations synchronize the remaining mode in the orthogonal polarization cooperatively with their total intensity variation. Information sender-mediator-receiver relationships among modes, which represent the dynamical roles of individual modes for establishing the observed three types of collective synchronizations, were identified in terms of an information circulation analysis.

Composite lattice pattern formation in a wide-aperture thin-slice solid-state laser with imperfect reflective ends.

We observed self-formations of multiple lasing channels and two-dimensional lasing patterns consisting of composite local modes having different lasing frequencies in a laser-diode-pumped wide-aperture thin-slice solid-state laser with imperfect reflective end surfaces. Global patterns resembling higher-order Hermite-Gaussian modes or possessing N-fold rotational symmetries were experimentally shown to appear due to the standard polished surface roughness of closely spaced reflective ends and nonlinear modal interactions.