Laser pulse shortest

A mode-locked Tksapphire laser, which can produce sub-ps pulses and is usually pumped by CW argon or Nd-YAG lasers. The shortest pulses coming from this laser type are exceptionally short, of the order of a few femtoseconds. 

The shortest laser pulse created to date has a duration (full width at half maximum) of 3.5 femtoseconds, and a center wavelength of approximately 800 nm (v 375 THz). However, because of the uncertainty principle, such a pulse has a very large range of frequencies Av. Use the uncertainty principle to determine... 

The shortest directly produced optical pulses, produced by Kerr-lens mode-locked Ti-sapphire lasers, last around 3.4fs = 3.4 x 10 15s. However, the minimum pulse duration is limited by the period of the carrier frequency (which is about 2.7 fs for Ti S systems). Some advanced techniques (involving high harmonic generation with amplified fs laser pulses) can be used to produce pulses as short as 10 16s for X < 30 nm. 

In 1997, the old dye laser record with respect to the shortest pulses was improved by a Ti sapphire laser. Pulses with a duration of 5 fs could be generated [9]. Despite the many advantages of solid-state femtosecond laser systems compared to dye lasers (power, compactness, no toxic dyes and solvents etc.), one drawback should be noted. The passive mode-locking process is not self-starting in many cases. 

Pulsed lasers with pulse widths less than 100 fs and as low as 10 fs are now commercially available. It is important to compare the timescale with some characteristic timescales involved in microscale energy transfer processes. As we have noted earlier, the electron-phonon scattering timescale is on the order of 100 fs in most metals and semiconductors at room temperature. This is also the shortest time it takes for the ions in the solid to undergo one vibrational period. In other words, the highest phonon frequency is about 1013 Hz which corresponds to 100 fs in time period. Such laser pulse widths are much shorter than the phonon-phonon scattering time at room temperature which is on the order of 10 ps. 

The duration of laser emission varies over several orders of magnitude. The shortest laser pulses generated so far have a duration of about 8 10 sec, which corresponds to about 4 wavelengths of the electromagnetic field. 

One of the shortest LASER pulses ever generated was 100 as with an uncertainty of 12 as. Using the Heisenberg uncertainty principle, calculate the uncertainty in the frequency of the LASER pulse. 

The shortest dye laser pulses were first obtained by Fork et al. [12]. Placing a combined prism and diffraction grating sequence into the cavity of their colliding-pulse mode-locked (CPM) dye laser, they could provide quadratic and cubic phase compensation and obtained pulses of 6fs full width half maximum (FWHM). However, the tunability of this special dye laser configuration is extremely restricted and limits the application to spectroscopic investigations rather severely. Therefore, sometimes old-fashioned and less sophisticated techniques such as the simple synchronous pumping of a dye... 

The shortest optical pulses actually used so far (1998) in ultrafast spectroscopic experunents were obtained by Shank and co-workers from an amplified CPM laser [ ]. In these extraordinary experiments, a sequence of a pair of prisms... 

One of the most important teclmiques for the study of gas-phase reactions is flash photolysis [8, ]. A reaction is initiated by absorption of an intense light pulse, originally generated from flash lamps (duration a=lp.s). Nowadays these have frequently been replaced by pulsed laser sources, with the shortest pulses of the order of a few femtoseconds [22, 64]. 

The shortest time delay in the pulsed laser experiments is limited either by the pulse width (in the picosecond time range) or by the shortest time the probe pulse can be delayed from the photolytic pulse (in the picosecond time range). The convenient long time delay could be accomplished by sending the probe pulse around the laboratory a few times (producing a delay time in the nanosecond range). 

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