Pulse duration

About: Pulse duration is a research topic. Over the lifetime, 19429 publications have been published within this topic receiving 286507 citations.

Femtosecond infrared pulses tunable from 9 to 18 mum at an 88-MHz repetition rate.

Abstract: Femtosecond mid-infrared laser pulses that are continuously tunable in the wavelength range from 9 to 18 µm are demonstrated. These nearly bandwidth-limited pulses are generated by phase-matched difference-frequency mixing within the broad spectrum of 20-fs pulses from a mode-locked Ti:sapphire laser in GaSe. A direct determination of the pulse duration at 11.5 µm gives a value of 140??fs. The average mid-infrared power of 1 µW is ?100 times greater than that for infrared generation by non-phase-matched optical rectification.

Pulse width effect in ultrafast laser processing of materials

Abstract: A systematic study of the influence of laser pulse width in ultrafast laser micromachining of silicon and stainless steel was carried out. Experiments were performed using a Ti:sapphire laser with 800 nm and 400 nm (frequency doubling) wavelengths in an air environment with a pulse duration ranging from 110 fs to 10 ps. Hole drilling and line cutting of silicon and stainless steel were studied. Structural details of the machined area were characterized using a number of techniques such as optical microscopy, atomic force microscopy and stylus profilometry. The effect of pulse width on melting was observed at ∼2.5 ps for stainless steel and at ∼5 ps for silicon. Also, the polarization effect on the laser machining is reported. The machined quality using femtosecond laser pulses with high energy fluence was found to be limited by the laser intensity contrast.

Optical information recording method

Abstract: A recording apparatus overwrites an input signal (s1) having pulse duration periods and pulse spacing periods to a optical disk by irradiation of a laser beam to form recording marks corresponding to the pulse duration periods. The apparatus includes detector (10) for detecting a leading edge of the pulse duration period and for producing a start signal thereupon, another detector (11) for detecting a trailing edge of the pulse duration period and for producing a stop signal thereupon, a pattern setting circuit (3) for setting a predetermined basic pattern, and a pattern generator (12) for generating the basic pattern from its beginning in response to the start signal and for terminating the generation of the basic pattern in response to the stop signal. The apparatus further includes a circuit (9, Ia, Ib, Ic, 4) for forming a modulated signal using a full or portion of the basic pattern produced from the pattern generator (12). The laser is produced by the modulated signal.

Nonlinear optical processes in a polydiacetylene measured with femtosecond duration laser pulses

Abstract: The temporal response of the third‐order nonlinear optical susceptibility in poly bis( p‐toluene sulfonate) of 2,4‐hexadiyne‐1,6 diol was determined by time‐resolved degenerate four‐wave mixing using tunable dye laser pulses with 300 fs duration. In the material’s absorption region these experiments were combined with saturated absorption techniques yielding a measurement for the excited state lifetime of 1.8 ps. Off resonance the nonlinear response was determined to be optical pulse width limited.