16-08-2012, 04:21 PM
NONLINEAR SECOND ORDER HARMONICS
[attachment=31740]
INTRODUCTION
Impressive progress has been made in nonlinear optical waveguides made of LiNbO3, LiTaO3, and optical crystals
Organic materials has the combined advantage of synthetic flexibility for chromophore design and synthesis together with the fast purely electronic response.
The nonlinear properties of high-Tc superconductors have been of great concern in microwave applications, although the microscopic origins of the nonlinear response still remain uncertain.
By comparing the second harmonic signal generated in a series of ZnO films with different crystalline and thickness, so it was concluded that a significant part of the second harmonic signal is generated at the grain boundaries and interfaces.
Linear and nonlinear optical properties of materials are also of importance for development of photonic and electronic technologies.
What is SHG and NLO
A non-linear process is called as Second Harmonic Generation (SHG) where a photon at frequency 2ω is generated from the interaction between intense light at frequency ω and a nonlinear medium.
Observable in very intense light field.
After the invention of the optical laser, which provided the source of intense light, optical second harmonic generation was observed in a quartz crystal.
Other than the non-Centro symmetric quartz crystal, Second Harmonic Generation (SHG) was also observed from the centrosymmetric crystal of calcite.
Generation of second harmonics using semiconductors
Second harmonic (SH) generation through a second order optical effect requires a material that lacks inversion symmetry or a symmetry-breaking interface.
However, the presence of an electric field can permit SH generation through a third-order process called electric-field-induced second-harmonic (EFISH) generation.
CONCLUSION
With the advent of laser beam it is now possible to have electric fields, which are strong enough for many non-linear effects to be observed.
The crystallographic symmetry of these crystals is such that they respond differently when the direction of the external electric field is inverted.
Now researchers are interested in generating optical nonlinear second order harmonics from organic materials.
[attachment=31740]
INTRODUCTION
Impressive progress has been made in nonlinear optical waveguides made of LiNbO3, LiTaO3, and optical crystals
Organic materials has the combined advantage of synthetic flexibility for chromophore design and synthesis together with the fast purely electronic response.
The nonlinear properties of high-Tc superconductors have been of great concern in microwave applications, although the microscopic origins of the nonlinear response still remain uncertain.
By comparing the second harmonic signal generated in a series of ZnO films with different crystalline and thickness, so it was concluded that a significant part of the second harmonic signal is generated at the grain boundaries and interfaces.
Linear and nonlinear optical properties of materials are also of importance for development of photonic and electronic technologies.
What is SHG and NLO
A non-linear process is called as Second Harmonic Generation (SHG) where a photon at frequency 2ω is generated from the interaction between intense light at frequency ω and a nonlinear medium.
Observable in very intense light field.
After the invention of the optical laser, which provided the source of intense light, optical second harmonic generation was observed in a quartz crystal.
Other than the non-Centro symmetric quartz crystal, Second Harmonic Generation (SHG) was also observed from the centrosymmetric crystal of calcite.
Generation of second harmonics using semiconductors
Second harmonic (SH) generation through a second order optical effect requires a material that lacks inversion symmetry or a symmetry-breaking interface.
However, the presence of an electric field can permit SH generation through a third-order process called electric-field-induced second-harmonic (EFISH) generation.
CONCLUSION
With the advent of laser beam it is now possible to have electric fields, which are strong enough for many non-linear effects to be observed.
The crystallographic symmetry of these crystals is such that they respond differently when the direction of the external electric field is inverted.
Now researchers are interested in generating optical nonlinear second order harmonics from organic materials.