Second order optical nonlinear self-active laser crystals

All-solid state compact lasers (IR, red, green, blue, uv) are useful today for a large variety of applications: TV, high density optical storage, laser printing, medecine, gaz laser reaplacement, bio-fluorescence, sub-marine communications... They are mainly based on frequency conversion of commercial laser emissions from nonlinear optical processes. I have investigated an attractive class of materials: the self-active laser crystals in which the laser generation and the nonlinear optical interaction take place inside the same material.

SFD: self-frequency doubling
SSFM: self-sum frequency mixing
SDFM: self-difference frequency mixing
OPO: Optical parametric oscillator
Vertical arrows: direction of the polarization corresponding to the higher or lower index of refraction

They are promising for compact and robust devices. First these are the self-frequency doubling crystals emitting in the green or red spectral range: LiNbO3 :Mg2+/Zn2+/Sc3+/W6+ :Nd3+/Yb3+, Ba2NaNb5015 :Nd3+, K3Li2Nb5015 :Nd3+, YAl3(BO3)4 :Nd3+ (NYAB).

Thr Nd3+ and Yb3+ ions spectroscopy has been studied, the phase matching wavelengths versus crystal composition have been determined. The stimulated emission cross-section is higher in p than in s polarization for niobate crystals. This is a desadvantage because frequency doubling needs an ordinary laser wave, the doubled frequency wave being extraordinary. On the contrary, in the case of NYAB the crystal emits usually a s-polarized wave.

A. Brenier, C. Madej, C. Pédrini, G. Boulon
Luminescence of ytterbium doped LiNbO3:MgO under uv excitation.
Radiation Effects and Defects in Solids, vol. 135 (1995) 77.


G. Foulon, M. Ferriol, A. Brenier, M.-T. Cohen-Adad, G. Boulon
Laser heated pedestal growth and optical properties of Yb doped LiNb03 single crystal fibers.
Chemical Physics Letters, 245 (1995) 555.


G. Foulon, A. Brenier, M. Ferriol, A. Rochal, M. T. Cohen Adad, G. Boulon
Laser heated pedestal growth and optical properties of Nd3+-doped
Li1-xNb1-xWxO3 single crystal fibers.

Jounal of Luminescence, 69 (1996) 257.


D. Jaque, J. A. Sanz, J. Capmany, J. Garcia Solé, A. Brenier, G. Boulon,
Continuous wave laser properties of 4F3/2-->4I13/2 transition of Nd3+ in LiNbO3 :ZnO nonlinear crystal.
Applied Physics B 68 (1999) 1-4.


G. Foulon, A. Brenier, M. Ferriol, M.-T. Cohen-Adad, G. Boulon
Laser heated pedestal growth and spectroscopic properties of Nd3+ doped
Ba2NaNb5O15 single crystal fibers.

Chemical Physics Letters, 249 (1996) 381.


G. Foulon, A. Brenier, M. Ferriol, G. Boulon
Nonlinear laser crystal as blue converter : laser heated pedestal
growth, spectroscopic and second harmonic generation properties of pure
and Nd3+ doped K3Li2Nb5O15 single crystal fibers.

Journal of Physics D : Applied Physics 29 (1996) 3003-3008.


M. Ferriol, G. Foulon, A. Brenier, M.-T. Cohen-Adad, G. Boulon
Laser heated pedestal growth of pure and Nd3+-doped potassium lithium niobate single
crystal fibers.

Journal of Crystal Growth 173 (1997) 226-230.


D. Jaque, J. Capmany, J. A. Sanz-Garcia, A. Brenier, G. Boulon, J. Garcia Sole
Nd3+ ion based self frequency doubling solid state lasers
Optical Materials vol. 13 n°1 (1999) 147.

At the present time, NGAB is among the most promising self-active laser crystals:

A. Brenier, Chaoyang Tu, Minwang Qiu, Aidong Jiang, Jianfu Li, Baihang Wu, "Spectroscopic properties, self-frequency doubling and self-sum frequency mixing in GdAl3(BO3)4:Nd3+", Journal of Society of America B (2001).

I have investigated another application of the self-active crystals: the self-sum frequency mixing laser. In this laser, the 1062 nm NYAB laser emission is mixed with the pump wave at 590 nm (Nd3+ 4G5/2-2G7/2 levels) inside the same crystal, generating uv (590+1062-->379 nm). Pumping at 750 nm (4F7/2-4S3/2) leads to blue generation at 456 nm.

The phase matching angle versus the Nd3+ absorption level is given by the following arrows:

A. Brenier, G. Boulon, D. Jaque, J. Garcia Solé
Self-frequency-summing NYAB laser for tunable blue generation
Optical Materials 13 (1999) 311.


A. Brenier, G. Boulon
Self-frequency-summing NYAB laser for tunable uv generation
Journal of Luminescence 86 (2000) 125.

I have made a modeling of the self-frequency doubling and summing lasers (plane waves and gaussian waves):

A. Brenier
Numerical investigation of the CW end-pumped NYAB and LiNbO3:MgO:Nd3+
self-doubling lasers.

Optics Communications 129 (1996) 57.


A. Brenier
Modeling of the NYAB self-doubling laser with focused gaussian beams
Optics Communications vol. 141 n°3 and 4 (1997) 221.

A. Brenier
The self-doubling and summing lasers: overview and modeling.
Journal of Luminescence, vol. 91 n°3-4 (2000) 121.

 

 

 

When a fundamental wave is frequency doubled by propagating in a second-order nonlinear optical media, the doubled frequency wave converts back to the fundamental one after a path length so-called the coherence length. A phase is generated. The larger the photon flux, the larger the phase. Consequently, for a gaussian wave, the acumulated phase will not be the same at the centre of the beam and in the wings. The fundamental and the frequency-doubled waves are then refracted due to cascaded nonlinearities. The interesting question is to know if the refraction can cancel the spread of the waves due to diffraction. In other words, is it a way to propagate solitons ? The answer is "yes" and the gaussian solitons belong to a one-parameter family depending on the root of a cubic polynomial.

A. Brenier
(2+1) dimensional gaussian solitons due to cascaded second order nonlinearities.
Optics Communication 156 (1998) 58.

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