Effects of self-induced ellipse rotation and self-focusing in a Q-switched laser cavity

Hsu, Ryan H.; Shen, Y. R.

doi:10.1364/ao.21.002608

Cited by 2 publications

(2 citation statements)

References 15 publications

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“…Pulse stretching was demonstrated in a Q-switched ruby laser by using a nematic liquid crystal EBBA (p-ethoxy-benzylidene-p-butylaniline) as the nonlinear optical ellipse rotation medium in the cavity to introduce intensity dependent cavity loss due to rotation of polarization ellipse (Murphy & Chang, 1977). Stretching of pulses of 70 ns duration by a factor of 4 has been observed by placing liquid crystal MBBA (n-pmethoxybenzylidene-p-butylaniline) in the cavity of a Q-switched ruby laser along with other polarizing elements for self-induced ellipse rotation (Hsu & Shen, 1982). A light scattering process is said to be stimulated if the fluctuations in the optical properties that cause the light scattering are induced by the presence of the light field.…”

Section: Pulse Stretching By Intracavity Nonlinear Materialsmentioning

confidence: 99%

Temporal Stretching of Laser Pulses

Khare¹,

Shukla²

2010

Coherence and Ultrashort Pulse Laser Emission

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Section: Pulse Stretching By Intracavity Nonlinear Materialsmentioning

confidence: 99%

Temporal Stretching of Laser Pulses

Khare¹,

Shukla²

2010

Coherence and Ultrashort Pulse Laser Emission

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“…Other authors have used similar nonlinear media in order to compress Q-switched pulses by self-induced ellipse rotation and self-focusing. [5][6][7] In these cases the Q switching was provided by external elements (rotating prism and electro-optic modulator). Mode locking has been obtained 8 • 9 by using nonlinear devices that exhibit a large optical Kerr effect, but in both cases elliptical rotation in a nonlinear medium was used.…”

mentioning

confidence: 99%

Q switching by self-focusing

Marconi¹,

Martı́nez²,

Diodati³

1985

Opt. Lett.

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A novel passive technique for obtaining short-laser-pulse emission is presented. A cell with a high-second-order refractive-index liquid is included in an unstable laser cavity. The external self-focusing introduced by the cell at higher optical intensities reduces the diffraction losses, producing modulation of the gain and Q switching of the cavity. Compared with saturable absorbers, this method provides better mode quality, avoids filamentary emission, and is not restricted in wavelength. Experimental results are presented that are in good agreement with the numerical model developed.The generation of short and high-power laser pulses by passive methods has been of great importance in recent years. Many organic dyes with absorption peaks at the laser wavelength and short relaxation times have been used as saturable absorbers for passive Q switching of solid-state lasers. 1 -4 The main advantages of such passive methods are simplicity and the low cost of the equipment. Nevertheless, this modulation technique has the important drawback of absorber degradation, which changes the initial conditions with use, so that the dyes become unreliable when they are used for long periods of time. Other disadvantages are that the dye to be used must have an absorbing peak tuned with the laser wavelength and that the bleaching process may favor filamentary emission of the laser.In this Letter, we present a novel technique to obtain short pulses by passive modulation of the gain. This new method has the traditional advantages of the passive technique without the drawbacks mentioned above. The new system makes use of the self-focusing effect in a liquid with a high-second-order refractive index n 2 • A cell containing such a liquid is introduced into an unstable laser cavity, and the self-focusing introduced at higher intensities then reduces the diffraction losses by changing the optical configuration of the resonator. Other authors have used similar nonlinear media in order to compress Q-switched pulses by self-induced ellipse rotation and self-focusing. [5][6][7] In these cases the Q switching was provided by external elements (rotating prism and electro-optic modulator). Mode locking has been obtained 8 • 9 by using nonlinear devices that exhibit a large optical Kerr effect, but in both cases elliptical rotation in a nonlinear medium was used.The cell in our laser, when in contact with one of the spherical mirrors of the cavity, acts as a positive lens with a focal length variable with the field intensity. We assume that the cell length is much smaller than the cavity length and that only phase distortion occurs in the cell, with no change in the amplitude profile. Hence the cell changes the mirror's effective radius, and the resonator configuration becomes intensity dependent.In the aberrationless approximation, the focal length induced by the external self-focusing can be calculated bylO 0146-9592/85/080402-03$2.00/0where a is the spot size, d is the cell length, n 2 is the second-order refractive index, and E is the fi...

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Effects of self-induced ellipse rotation and self-focusing in a Q-switched laser cavity

Cited by 2 publications

References 15 publications

Temporal Stretching of Laser Pulses

Temporal Stretching of Laser Pulses

Q switching by self-focusing

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