Measurement of the background energy content of Nd-glass picosecond pulses with saturable absorbers

1988

Appl. Phys. B

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Abstract. The passive and hybrid Q-switching and mode-locking of solid-state lasers, dye lasers, semiconductor lasers and gas lasers is reviewed. The dynamics of saturable absorbers and reverse saturable absorbers is illustrated. The nanosecond pulse generation by passive and hybrid Q-switching of low-gain active media is described. The picosecond and femtosecond pulse generation by passive and hybrid mode-locking in low-gain and highgain active media is analysed. The performance data of passively and hybridly mode-locked cw femtosecond dye lasers are collected. The pulse shortening of ultra-fast pulses with saturable absorbers in intra-cavity and extra-cavity configurations is discussed. PACS: 42.55The photonic switching of lasers provides an important technique to generate short light pulses in the nanosecond to femtosecond time regime. The photons generated in the laser modify the transmission of the switching elements and cause the formation of short pulses. Saturable absorbers serve as intensity or energy dependent coupling elements in most cases. But occasionally intensity and energy-dependent refractive index changes have been applied. Nanosecond light pulses are generated in passively Q-switched lasers. The passive mode-locking of laser leads to the generation of nanosecond, picosecond or femtosecond pulse trains. The actual pulse durations depend on the spectroscopic data of the active media and of the passive elements.The nonlinear response of absorbers to light radiation is introduced in the next section [1][2][3][4][5][6][7][8][9]. The passive, and the hybrid Q-switching are discussed in . The passive, and the hybrid modelocking are described in Sect. 3. A distinction is made between the mode-locking of low-gain and high-gain active media [35 45]. The simultaneous Qswitching and mode-locking is discussed shortly in Sect. 4. A final section is devoted to the intra-cavity and extra-cavity pulse shortening with saturable absorbers [46][47][48][49][50].

Section: Pulse Shortening With Saturable Absorbersmentioning

confidence: 99%

Passive Q-switching and mode-locking for the generation of nanosecond to femtosecond pulses

1988

Appl. Phys. B

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“…Laser beams with severe diffraction pattern were smoothed by focusing the light and putting an absorber cell in the focal plane (spatial filtering [20,21] with saturable dye instead of pinhole; the Airy rings of Fraunhofer diffraction are formed in the focal plane). In our experiments with picosecond light pulses the saturable absorber additionally eliminates the background energy content [22] and shortens the pulse duration [23].…”

mentioning

confidence: 99%

Apodizing of intense laser beams with saturable dyes

Fröhlich

1979

Optics Communications

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The diffraction of laser light by optical components is reduced with graded apertures. The nonlinear transmission of light through saturable absorbers is applied to form soft apertures. Dye cells in front of amplifiers and at the focal region of spatial filters were used to generate smooth beam profiles.Optical components in the light path act as apertures which truncate the light beam and cause diffraction. In the near field behind an aperture (/ ^ r^/X; r a radius of aperture, X laser wavelength; distance / ^ 25 m for r a = 0.5 cm and X = 1 jum) the Fresnel diffraction modulates the spatial intensity distribution. In the far field (/ > r^/X) the Fraunhofer diffraction generates Airy rings.The distortion of the beam profile by diffraction causes severe problems in laser physics. The profile changes with incident beam diameter and beam shape, with aperture width and distance behind the aperture [1,2]. A quantitative analysis of nonlinear optical and spectroscopic effects is difficult with rippled beams.

“…It reduces the resolution in time-resolved spectroscopic measurements. For intense pulsed picosecond lasers various techniques have been applied to determine the background energy content [1][2][3][4][5][6][7][8][9][10][11][12][13][14] (overexposed photodetectors [ 1,2 ], photo-conductivity of silicon switches [3,4], contrast ratio of two-photon fluorescence traces [2,5], efficiency of third harmonic generation [6,7] and three-photon fluorescence [2,8], parametric fourphoton interaction [ 9,10 ], frequency mixing of fundamental and second harmonic light [11], streak camera measurements [12], and saturable absorption [ 13,14 ] ). For cw mode-locked picosecond and femto-second lasers [15][16][17][18] no detailed background energy content measurements have been reported yet.…”

Section: Introductionmentioning

confidence: 99%

Measurement of background energy content of a linear cw colliding pulse mode-locked dye laser

Bäumler

1991

Optics Communications

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The background energy content of a linear cw CPM rhodamine 6G-DODCI femtosecond dye laser is determined by timeresolved measurement of the Rayleigh scattered signal in a colloidal silicon dioxid suspension with an ungated inverse timecorrelated single photon counting system. A constant background intensity signal is observed outside the temporal region of the instrument response function of the detection system. Assuming the same background intensity level within the temporal region of the instrument response function, an average background intensity level of approximately 2.5 x I 0 ~ of the peak pulse intensity, and a background energy content of approximately 2 × 10 3 of the pulse energy are found.