Measurement of modal dispersion in optical fiber by means of acousto-optic coupling.

We show that frequency-wavelength tuning characteristics of acousto-optic coupling can be used for measuring the difference of effective index, group index, and chromatic dispersion between core and cladding modes in single-mode fibers. Chromatic dispersion measurements of a 30-cm-long conventional single-mode fiber, a nonzero dispersion-shifted fiber, and a dispersion-compensating fiber with this new method are presented for the wavelength range 1500-1600 nm. Qualitative agreement with independently measured data is obtained.

Structures of bromoalkanes' photodissociation in solution by means of ultrafast extended x-ray absorption fine-structure spectroscopy.

The structures of initial and final products of bromoalkanes' photodisociation reaction in cyclohexane solution have been measured with a bond length accuracy of 0.02 A by means of ultrafast time-resolved extended x-ray absorption fine structure spectroscopy. The photoredaction mechanism is also discussed.

Picosecond X-Ray Pulses Generated in a Diode Driven by 193-nm Picosecond Laser Pulses.

A new technique for the generation of picosecond x-ray pulses is presented. Picosecond laser pulses are used to generate ultrashort electron pulses in a conventional x-ray diode in which the cathode is replaced by a photocathode. In the experiments presented, 9-ps UV pulses are employed to produce characteristic x-ray pulses with duration in range of 20-90 ps at a repetition rate of 300 Hz. This technique is inherently capable of subpicosecond x-ray pulses and synchronization of the x-ray pulses with the laser pulses or other ultrafast devices with picosecond accuracy.

Third-harmonic generation in barium borate.

The cubic nonlinear susceptibility of barium metaborate was employed for the generation of phase-matched third-harmonic generation (THG) of 1.053-microm pump radiation. The various processes that are responsible for THG in this crystal are discussed and experimental results for types I and II phase matching are presented. THG power of 50 microW is recorded with an average pump power of 800 mW of 1-kHz repetition rate picosecond pulses.

High-efficiency stimulated Brillouin scattering of KrF laser radiation in SF(6).

Stimulated Brillouin scattering of KrF laser radiation focused in SF(6) gas at pressures of 1.4 to 9.8 atm has been studied experimentally. For an input linewidth of 0.08 cm(-1) and focal lengths of 1 and 2 m, reflectivities of 80% have been measured. Pulse compression up to peak intensities of two times the pump intensity has been achieved in a pulse that is partially phase conjugate to the pump pulse. At high pressures a short backward Raman spike was observed preceding the Brillouin backscattered signal.

Phase conjugation and pulse compression of KrF-laser radiation by stimulated Raman scattering.

An experimental investigation of phase conjugation and pulse compression by stimulated Raman scattering in methane gas using a narrow-linewidth KrF-laser pump is presented. Good spatial reproduction of the pump beam is observed at reflectivities of up to 80%. With a pump-pulse duration of 25 nsec, backward Stokes pulses of 5-nsec duration with 40% of the 100-mJ pump energy were obtained.

Actively mode-locked and Q-controlled Nd:glass laser.

A Q-controlled Nd:glass ring laser system has been developed which is actively mode-locked by means of either KD *P or LiNbO(3) electro-optic modulators and is capable of producing 1.5 mJ, 100 ps, 1.06 mum pulses synchronized to better than 400 ps to an external event. By using prelase methods or saturable absorbers shorter pulses from 37 to 15 ps duration can be generated with poorer synchronization.