SourcesCP 





Presentation

Structures fabriquées au LPN. 

This project aims at the conception, the fabrication and the use of efficient and compact sources based on the exploitation of second order nonlinear effects. The investigated approach consists in using semiconductor materials structured at a subwavelength scale. These materials exhibit very large nonlinear quadratic susceptibilities ( 1 or 2 order of magnitude larger than usual materials). A periodical structuration in such materials enables the compensation of the chromatic dispersion (phasematching achieved) and to slow down the waves interacting nonlinearly.

1  1D Microsources based on AlOx/AlGaAs Bragg mirrors
Using microstructures presenting a periodic modulation of the refractive index was proposed as soon as the first steps of second order nonlinear optics in order to achieve phasematching and as a consequence to obtain large conversion efficiency. To apply experimentally this proposition called quasiphase matching, a solution consists in using a periodical distribution of the second order nonlinear susceptibility (nonlinear property of the material) in a medium with an uniform refractive index (linear property of the material) (See R.L. Byer et al). This periodicity put back in phase the nonlinear polarization with the generated waves.
Alternatively, phase matching can be obtained by taking benefit of the dispersive properties of a medium that presents a periodical distribution of the refractive index. In these very particular conditions, the periodicity leads to a decrease of the group velocity of the interacting waves.
This property has been exploited to enhance second harmonic generation. 1D stratified structures (refractive index periodical in 1 dimension) have been proposed by Scalora et al. to obtain very efficient second harmonic generation, the structure enabling phase matching as well as enhancement of the field. These 1D structures exhibit a "stopband" that prevents the light from propagating in a spectral range centered on the Bragg wavelength in a similar way to photonic band gap materials. They are called 1D photonic crystals (1DPCs) or Bragg mirrors. On the borders of the spectral region of the stopband (band edges), narrow resonances are observed. In these resonances, the reflectivity is null and transmission is maximum. The zero reflectivity corresponds to a total dephasing of Pi for the transmitted beam.


Structures fabricated at LPN. 

This characteristic
of 1DPC dispersion make phasematching possible for second harmonic
generation if the 2n ^{th} lateral resonance of the second
order stopband is exactly at 2 times the frequency of the n ^{th}
resonance of the first order stopband. The electromagnetic field
is also enhanced when its frequency is set to these "distributed
Bragg resonances" ones.
It can be shown by a
simple analytical calculation based on the coupled modes theory that,
in a Bragg structure sufficiently long (L is the length), the field
enhancement is proportional to L and the intensity (I _{F})
goes like L ^{2}. Because the SHG (I _{SH}) intensity
varies like L ^{2} and I _{F}^{2}, we find:
:
I_{SH}~L^{6}
This constitutes a
spectacular difference when it is compared to the second harmonic
generation efficiency in a bulk medium which goes like L ^{2}.
We have also
recently demonstrated such an overquadratic dependence of second
harmonic generation efficiency in a 1DPC made of AlOx/
GaAlAs (cf. figure below).
2 2D nonlinear
microsources
We have developed a
2D finite difference time domain (FDTD) software able to take into
account second harmonic generation (SHG) in 1D or 2D structured
materials. We applied this code to a semiconductor defective photonic
crystal (PC) waveguide where phasematching is obtained by
engineering the Bloch modes dispersion. This nonlinear FDTD (NLFDTD)
method constitutes an intuitive alternative solution able to analyse
the SHG in an arbitrary 2D structure with a reasonable time
consumption at expend of loosing generality. In particular, the
method works in the nondepleted pump approximation and neglects
intrapulse chromatic dispersion. It is based on the implementation
of two parallel linear FDTD codes. The first operating at FF
wavelength and the second at SH wavelength. The quadratic
nonlinearity is only taken into account for the SH, which is not
coupled back at the FF wavelength. Chromatic dispersion is considered
simply by taken the actual refractive index at FF and SH wavelength.
This artificial separation of FF and SH propagation allows to easily
identify FF and SH distribution and other relevant physical
parameters.
3Current Projects
L^{6} law in
guided optics:
We propose to adapt
the approach we chose to achieve large second harmonic generation
efficiency in vertical Bragg mirrors (use of the anomalous dispersion
at the photonic bandedges) to a waveguide configuration. Here, the
1DPC is deeply etched in a ridge waveguide. The advantage of this
configuration is double: strong spatial confinement and availability
of the maximum nonlinear tensor component. However, this needs
stateofthe art technology like it is shown in the picture below.
2D photonic crystrals:
We are exploring
also 2D PCs in second order nonlinear regime. Two configurations are
being investigated: the small linedefect optical waveguides (see
figure) and the perfectly periodic structures that behave like 2D
distributed resonators.
Members
Contacts
And also...
PublicationsPublication in journals
 Lossless backward secondharmonic generation of extremely narrow subdiffractive beams in twodimensional photonic crystals
, C. Nistor, C. Cojocaru, T. J. Karle, F. Raineri, J. Trull, R. Raj, K. Staliunas, Phys. Rev. A 82, 33805 (2010)
 Phase locked second and third harmonic localization in semiconductor cavities , V. Roppo, C. Cojocaru, G. D'Aguanno, F. Raineri, J. Trull, Y. Halioua, R. Vilaseca, J. Optoelectron. Adv. Mater. 12, 57 (2010)
 Field localization and enhancement of phaselocked second and thirdorder harmonic generation in absorbing semiconductor cavities
, V. Roppo, C. Cojocaru, F. Raineri, G. D'Aguanno, J. Trull, Y. Halioua, R. Raj, I. Sagnes, R. Vilaseca, M. Scalora, Phys. Rev. A 80, 43834 (2009)
 Secondharmonic generation in onedimensional photonic edge waveguides , Y. Dumeige, F. Raineri, A. Levenson, X. Letartre, Phys. Rev. E 68, 65535 (2003)
 Nonlinear decoupled FDTD code: phasematching in 2D defective crystal
, F. Raineri, Y. Dumeige, X. Letartre, A. Levenson, Electron. Lett. 38, 1704 (2002)
 Chi(2) semiconductor photonic crystals
, Y. Dumeige, I. Sagnes, P. Monnier, P. Vidakovic, C. Meriadec, A. Levenson, J. Opt. Soc. Am. BOpt. Phys. 19, 2094 (2002)
 Deep in situ dryetch monitoring of IIIV multilayer structures using laser reflectometry and reflectivity modeling
, H. Moussa, R. Daneau, C. Meriadec, L. Ferlazzo, I. Sagnes, R. Raj, J. Vac. Sci. Technol. AVac. Surf. Films 20, 748 (2002)
 Phasematched frequency doubling at photonic bandedges: efficiency scaling as the fifth power of the length , Y. Dumeige, I. Sagnes, P. Monnier, P. Vidakovic, I. Abram, C. Meriadec, A. Levenson, Phys. Rev. Lett. 89, 43901 (2002)
 Photonic band edge effects in finite structures and applications to chi(2) interactions , G. D'Aguanno, M. Centini, C. Sibilia, M. Bertolotti, Y. Dumeige, P. Vidakovic, A. Levenson, M. Scalora, M. J. Bloemer, C. M. Bowden, Phys. Rev. E 64, 16609 (2001)
 Nonlinear frequency conversion: choose your color FROM the photonic band edge , M. Scalora, M. J. Bloemer, C. M. Bowden, G. D'Aguanno, M. Centini, C. Sibilia, M. Bertolotti, Y. Dumeige, I. Sagnes, P. Vidakovic, A. Levenson, Optics and Photonic News 25, 1585 (2001)
Contracts and projects
International Projects
PHC PICASSO : Active non diffractive light propagation through nonlinear photonic crystals
Reference contract : Binational project supported by the Egide between Spain and France
LPN leader(s): Rama Raj, Fabrice Raineri Main goals : The motivation of this project is to combine non diffractive propragation in photonic crystals and nonlinear optics. (20092010)
Past and current Internship TrainingPostdocsPhDs
 Nonlinear optics in IIIV semiconductorbased photonic crystals
F. Raineri(20011001 / 20041031)
Contact : A. Levenson
Group : Nonlinear Photonic and Quantum Information (PHOTONIQ)
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This work concerns both theoretical and experimental studies of nonlinear optics in photonic crystals based on IIIV semiconductors. Photonic crystals, with their lattice dimensions of the order of the wavelength of the light, offer efficient ways to control the propagation of the electromagnetic fields. For instance, by adjusting the optogeometrical parameters of these structures, it is possible to engineer the dispersion of the matter such as the light propagation is forbidden in every directions of the space. The aim of this PhD thesis is to demonstrate that this possibility to engineer the dispersion can also be advantageously used to enhance nonlinear interactions between light and matter. We will see that 1D and 2D photonic crystals are adequate structures to obtain efficient frequency doubling because they enable phase matching in very nonlinear materials such as AlxGa1xAs and the slowing down of the light as well. We will also show that, by combining the nonlinear properties of IIIV semiconductors to 2D photonic crystals, it is possible to realize the basic active functionalities for alloptical data processing such as laser sources, amplification, ultrafast switching…
 Integrated optical circuits based on hybrid photonic crystal structures in InP / Silicon optical waveguide
Y. Halioua(20071001 / 20111001)
Contact : F. Raineri
, R. Raj
Group : Nonlinear Photonic and Quantum Information (PHOTONIQ)
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 Study of hybrid structures: Nonlinear IIIV semiconductor photonic crystals/ silicon waveguide
A. Bazin(20090901 / 20121001)
Contact : F. Raineri
, R. Raj
Group : Nonlinear Photonic and Quantum Information (PHOTONIQ)
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