12 GHz passive harmonic mode-locking in a 1.06 μm semiconductor optical amplifier-based fiber laser with figure-eight cavity configuration.

We report the generation of passively harmonic mode-locked pulses using a 1.06 μm semiconductor optical amplifier (SOA) in a figure-eight laser configuration operated in the all-normal-dispersion regime. Different orders of harmonic mode-locking can be obtained from 30 MHz to 12.

Chaos suppression in a Nd:YVO4 laser by biharmonical pump modulation.

This work demonstrates the suppression of chaos in a Nd:YVO(4) laser by biharmonical pump modulation (the first for chaos-inducing and the second for chaos-suppressing). The laser exhibits chaotic behavior when only the first signal is applied for pump modulation and its frequency is adjusted close to the relaxation-oscillation frequency. Adding the second signal with subhamonic and a specific phase difference to the first modulation signal will reshape the modulated waveform of the pump beam to suppress the aforementioned chaotic behavior.

Strain differences in the chronic mild stress animal model of depression.

Hypothalamic-pituitary-adrenal (HPA) axis dysfunction has been implicated in depression pathology. In the present study, we used a chronic mild stress (CMS) animal model of depression to examine the responses of three strains of rats that have different HPA axis responsiveness; and whether the behavioral changes observed are correlated with changes in hippocampal cell proliferation and survival. In addition, in most of the CMS experiments the rats are kept in singly housed condition.

Manipulation of operation states by polarization control in an erbium-doped fiber laser with a hybrid saturable absorber.

We propose an operation switchable ring-cavity erbium-doped fiber laser (EDFL) via intra-cavity polarization control. By using a semiconductor saturable absorber mirror in the EDFL cavity, stable Q-switching, Q-switched mode-locking, continuous-wave mode-locking, pulse splitting, and harmonic mode-locking pulses can be manipulated simply by detuning a polarization controller while keeping the pump power at the same level. All EDFL operation states can be obtained under the polarization angles detuning within 180 degrees.

Difference in magnitude of psychostimulant-induced extracellular norepinephrine in the ventral tegmental area contributes to discrepant prefrontal dopamine outflow.

The dopamine (DA) efflux in the medial prefrontal cortex (mPFC) can be modulated by the interaction between afferent norepinephrine (NE) and somatodendritic DA in the ventral tegmental area (VTA). However, it is unclear how locally administered amphetamine (AMPH) or cocaine in the VTA results in discrepant response of DA efflux in the mPFC. In this study, intra-VTA infusion of AMPH (1000 microM) or cocaine (200 microM) in anesthetized rats was employed to study the concurrent profile of extracellular DA level in the VTA and mPFC.

Spatiotemporal dynamics of a passively mode-locked Nd:GdVO(4) laser.

By examining beam patterns, temporal pulse forms, and radio-frequency spectra as functions of resonator configuration and pump power, we found that a passively mode-locked Nd:GdVO4 laser exhibited four main regimes of operation that were single-transverse-mode Q-switched mode locking (QSML), single-transverse-mode continuous-wave mode locking (CWML), multiple-transverse-modes QSML, and multiple-transverse-modes CWML. The effect of multiple transverse modes on CWML was giving rise to amplitude instability in the pulse train. In the regime of multiple-transverse-modes QSML, we observed the phenomenon of spatiotemporal dynamics that spatial patterns vary with the time.

A single intrategmental amphetamine exposure induces transient behavioral sensitization in the rats.

Repeated treatment with psychostimulant drugs induces enduring behavioral sensitization and neuroadaptations which may play an important role in the development of drug addiction. However, different number and time course in drug administration and various lengths of drug withdrawal were employed in the literature, and there were inconsistent findings in the profile of extracellular dopamine level related to behavioral sensitization. Therefore, the effects of the number of drug exposure and the length of drug withdrawal period on the sensitized behavioral response were investigated in this study.

Spontaneous generation of giant pulses in a diode-pumped Nd:YVO4 laser.

Spontaneous generation of giant pulses was observed from a diode-pumped Nd:YVO4 laser with a plane-concave resonator by adjusting the cavity length near the hemispherical resonator configuration and misaligning the cavity axis with respect to the pump beam. Self-pulsation occurs because of the beating among near degenerate modes being tuned to resonate with the relaxation oscillation of laser modes. By using a concave mirror of 10-mm radius of curvature, giant pulses were obtained at approximately 10 kHz with pulse widths as short as 2.

Suppression of spatial hole burning in a solid-state laser with the degenerate resonator configuration.

Under degenerate resonator configuration and tightly focused pump beam in a linear-cavity solid-state laser, the spatial hole-burning effect can be suppressed. This laser can attain very high intensity in the gain medium due to shrinkage of its beam waist to match the pump beam and therefore most of its gain is depleted even by a standing wave. This was demonstrated by a simulation with spatial dependent rate equations and experiment results of a plano-concave Nd:YVO4 laser.

Formation of off-axis beams in an axially pumped solid-state laser.

I show that an axially pumped solid-state laser is able to support off-axis beams in a plane-concave cavity when the cavity length is adjusted within a region close to the hemispherical resonator configuration. These beams are characterized by the fact that even if an object is placed inside the cavity on axis in front of the concave mirror they can still oscillate off-axially in a V-shape path. One can further select and manipulate the desired off-axis beam by inserting a mask into the cavity.