A new design of signal to noise ratio (SNR) measurement for single shot laser pulses, based on a stepped grating and an optical Kerr gate (OKG), is presented. A single shot laser pulse was simultaneously divided into multi-pulses in both time and space. Intensity-space distribution of laser multi-pulses, which was recorded with a CCD detector, was transformed into intensity-time distribution. Time resolution of 1.95 ps and detection time range of 42.9 ps were obtained, respectively. Moreover, optical spatial localization attenuators were introduced into optical path to acquire wide dynamic range in the SNR measurement and, as a result, the dynamic range has been extended remarkably.
We report the observation of intense spontaneous emission of green light from LiF:F(2):F(3) (+) centers in active channel waveguides generated in lithium fluoride crystals by near-infrared femtosecond laser radiation. While irradiating the crystal at room temperature with 405 nm light from a laser diode, yellow and green emission was seen by the naked eye. Stripe waveguides were fabricated by translating the crystal along the irradiated laser pulse, and their guiding properties and fluorescence spectra at 540 nm demonstrated. This single-step process inducing a waveguide structure offers a good prospect for the development of a waveguide laser in bulk LiF crystals.
Two-dimensional ‘single-crystal’ hafnia networks were synthesized by the high temperature
gas–solid reaction method. Transmission electron microscopy investigation shows that these
networks exhibit micrometre-scale external dimensions and nanometre-scale holes and
frame width. The formation of these novel structures is based on the vapour–solid growth
mechanism, and the boron nitride deposited on the networks’ surface plays a key role in the
growth procedure by selectively influencing the growth rate of the crystal faces. This
process involves the control of crystal surface properties and adsorption of the growth unit,
and is extendable to the fabrication of nanosystems either in two dimensions or in three
dimensions.
Two operating modes, independent self-mode-locking and cross-mode-locking, are presented in a two-beampumped double-cavity dual-wavelength femtosecond Ti:sapphire laser. Synchronization of femtosecond and picosecond laser pulses is achieved by properly adjusting the cavity length matching and distributing the pump laser powers in the two laser cavities, and moreover, a timing jitter of 517 fs between femtosecond and picosecond pulses is obtained, with wavelength tuning ranges around 36 and 22 nm in the femtosecond and picosecond cavities, respectively.
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