Prevalence of paternal perinatal depressiveness and its link to partnership satisfaction and birth concerns.

Depressive disorders have shown an increasing prevalence over the past decades. Growing evidence suggests that pregnancy and childbirth trigger depressive symptoms not only in women but likewise in men. This study estimates the prevalence of paternal perinatal depressiveness in a German community sample and explores its link to partnership satisfaction as well as birth-related concerns and concerns about the future. Data was gathered in a longitudinal study over the second and third trimester of their partner's pregnancy up to 6 weeks postpartum. In a two-stage screening procedure, 102 expectant fathers were assessed for symptoms of depression, anxiety, and partnership satisfaction using the Edinburgh Postnatal depression Scale (EPDS), the State/Trait Anxiety Inventory, a self-constructed questionnaire for birth concerns and the Questionnaire of Partnership. The prevalence of elevated depressive symptoms among expectant fathers was 9.8 % prenatally and 7.8 % postnatally. Prenatal relationship quality, prenatal EPDS scores, and birth concerns were significantly associated with and explained 47 % of the variance in paternal postnatal depressive symptoms. The prevalence of paternal depressive symptoms is a significant concern. Our findings point out the need for implementing awareness and screening for depressiveness in fathers in clinical routine in Germany as well as the necessity of developing a screening instrument for paternal birth-related anxiety.

Space-time coupling and collapse threshold for femtosecond pulses in dispersive nonlinear media.

Femtosecond space-time coupling effects in dispersive nonlinear media are investigated by a simple approximate method. The applicability of the method is verified by comparison with earlier numerical simulations. New results are presented for astigmatic beams as well as for negative dispersion. The position of the beam waist in the material changes the collapse threshold. For astigmatic beams, collapse is prevented for pulse durations shorter than a critical value.

Direct measurement of the spectral phase of femtosecond pulses.

We measure the spectral phase of femtosecond optical pulses using a time-frequency analog of Young's doubleslit interference. A pair of narrow slits in an opaque sheet selects two spectral frequencies from the femtosecond pulse spectrum in a zero-dispersion pulse stretcher. Measurement of the temporal phase of a family of beat frequencies obtained over a range of slit spacings yields the desired spectral phase directly. We demonstrate this technique by accurately measuring the quadratic phase added to 80-fs optical pulses by a 6.5-cm block of BK-7 glass.

Ultrashort-pulse second-harmonic generation in quasi-phase-matched dispersive media.

Ultrashort-pulse (<50-fs) second-harmonic generation in quasi-phase-matched dispersive media is analyzed in the regime of weak conversion with phase mismatch, group-velocity mismatch, and linear absorption accounted for. In addition to the expected increase in conversion efficiency, the quasi-phase-matched structure is shown to counteract pulse distortions.

400-Hz mechanical scanning optical delay line.

We have developed a simple, high-speed, nearly vibration-free, mechanically scanned, optical delay line suitable for femtosecond time-resolved signal-averaging measurements. We demonstrate a 2-ps time window autocorrelator with a display updated at 400 Hz. The delay line uses a dithering planar mirror as a time-varying linear phase ramp in the spectral plane of a modified grating-lens femtosecond pulse shaper. The time delay is linearly proportional to the angular deviation of the mirror. The high speed and low vibration are a result of the extremely small angular changes required to generate a large time delay.

Time- and spectral-domain evolution of subpicosecond pulses in semiconductor optical amplifiers.

The evolution of ultrashort pulses in semiconductor laser amplifiers is modeled, including the effects of gain dispersion, slow and fast carrier dynamics, and self-phase modulation, which includes an instantaneous response (n(2)). The temporal and spectral evolution of 2-ps and 500-fs pulses differ considerably. This is due mainly to saturation caused by the fast (heating) dynamics and to the phase modulation by n(2).

Harmonic generation with ultrashort pulses using nonlinear poled polymeric thin films.

An organic thin film is successfully utilized as the second harmonic element in an autocorrelation measurement of ultrashort 200-fs optical pulses.

Subpicosecond-pulse development in a colliding-pulse mode-locking dye laser pumped by a pulsed xenon laser.

We obtain 0.34-psec optical pulses by using a long-pulse xenon-ion laser as a pump source in a colliding-pulse mode-locking (CPM) configuration. The pump shape is an important parameter affecting the development of short pulses. Some characteristics of xenon- and argon-laser-pumped CPM systems are compared.

Highly synchronous mode-locked picosecond pulses at two wavelengths.

Cross-correlation widths of 2.2 psec between picosecond pulses at two wavelengths have been observed with a double-mode-locked dye laser. This was achieved after careful optimization and stabilization of the laser. The jitter in the laser output is deduced to be about 0.3 psec. The jitter in the round-trip time was also measured and foundto be about 0.3 psec. Other cases have been observed in which satellite pulses in the lasing wavelengths are clearly resolved.

Stability and astigmatic compensation analysis of five-mirror cavity for mode-locked dye lasers.

A five-mirror cavity suitable for passively mode-locked dye lasers is analyzed and also modeled on the computer. Simple approaches for constructing a compensated cavity are shown. Experiments are performed confirming the theoretical results.

Independent tunability of the double-mode-locked cw dye laser.

We report a new configuration that enables the double-mode-locked cw dye laser to be independently tunable. In addition, the output coupling at each of the two wavelengths can be independently specified. A series of oscillographs shows some interesting features unique to double mode locking and also shows the effects of varying the two cavity lengths with respect to each other.

Automated system for measuring gains in organic dyes.

An automated system for measuring the small-signal gain-vs-wavelength curves for organic laser dyes has been constructed. The system uses a measurement technique reported previously. The data are recorded on a digital recorder. The resulting gain-vs-wavelength curves are plotted on a microfilm plotter.