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1

Designing ultra-fast all-optical full-subtractor using the photonic crystal structure

Pakrai Forogh, Soroosh Mohammad, Ganji Jabbar

Optica Applicata

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2023

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Vol. 53, nr 1

99--109

EN

In this paper, a photonic crystal-based structure for an all-optical full-subtractor has been proposed. The structure includes six nonlinear resonant rings to transmit the incoming optical waves toward the output ports. Using the different radii for nonlinear rods made the possibility of the dropping operation for different amounts of optical intensities. The nonlinear rods are made of a doped-glass with an optical Kerr coefficient of 10–15 m2/W. To calculate the components of the optical waves throughout the structure, the finite-difference time-domain method has been used. The simulation results prove the correct functionality of the proposed structure. Besides, the maximum rise time of the device is equal to 2 ps. The contrast ratio and the area of the structure are around 8.08 dB and 2790 μm2, respectively.

2

Engineering the optical and mechanical properties exhibited by a titanium dioxide thin film with gold nanoparticles

Morales-Bonilla S, Torres-Torres C, Trejo-Valdez M, Torres-Torres D, Urriolagoitia-Sosa G, Hernandez-Gomez L H, Urriolagoitia-Calderon G

Optica Applicata

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2013

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Vol. 43, nr 4

651--661

EN

Thermo-optic and electrostrictive contributions to the nonlinear refractive index were observed in a titanium dioxide thin film with embedded gold nanoparticles. A sol–gel method was employed for preparing thin solid film samples. The nanosecond nonlinear optical properties and the Young’s modulus parameter were changed by shifting the optical absorption band associated with the localized surface plasmon of resonance of the gold nanoparticles with platinum. The third order nonlinear optical phenomena exhibited by the sample were induced by the second harmonic of a Nd-YAG laser with 532 nm wavelength; the nonlinear optical measurements were obtained by monitoring the transmittance and the amplitude modification for the vectorial components of the electric fields in a two-wave interaction. Optical evaluations were confirmed considering a straightforward measurement of the change in the refractive index of the sample when the sample was located in a Michelson interferometer.

3

Carrier Dynamics and Optical Kerr Effect of Titanium Dioxide Single Crystals by Femtosecond Transient Grating Spectroscopy

Yang X., Wang L., Nakato Y., Tamai N.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 4

715-727

EN

The photogenerated carrier dynamics and optical Kerr effect in rutile titanium dioxide (TiO2) single crystals with (100), (110), and (001) faces were examined by femtosecond transient grating spectroscopy. The diffraction signal of the intensity grating in bare TiO2 single crystal at 670 nm was considered to be due to free electrons or weakly trapped electrons nearby Ti4+ sites within the bulk. The decay curves of transient grating were strongly dependent on the excitation in tensity but not on the types of crystal faces. The subsequent inten sity-dependent relaxation was interpreted in terms of second-order electron-hole recombination kinetics with the rate constant of ~ 2×10-11 cm3s-1 for both (110) and (100) faces. The optical Kerr dynamics of bare TiO2 examined by resonant polarization grating and non-resonant intensity grating shows an ultrafast response similar to the system response function, indicating that the Kerr signal is mainly due to electronic polarization. By the excitation of conduction band electrons of reduced TiO2 with the excess energy of 1.7 eV, the relaxation time constant of hot electrons within the conduction band was estimated to be 310 fs. In the long time region, the propagation of acoustic wave of 1.28 GHz was observed, which was due to the excess energy of hot electron converted into the thermal energy by electron-phonon scattering followed by the thermal relaxation.

4

Beam switching at a nonlinear-linear interface

Nasalski W.

Journal of Technical Physics

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2000

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Vol. 41, no 3

201-218

EN

Reflection of a beam incident front a nonlinear Kerr medium at a nonlinear-linear dielectric interface is analysed for incidence close to the critical angle of total internal reflection. The problem is formulated and solved within the frame of a reduced variational technique. The solution obtained is interpreted in terms of aberrationless effects of nonlinear propagation and nonspecular effects of nonlinear reflection. A bistable switch in the reflected beam power, waist position and diameter, as well as in the beam ais direction, is demonstrated. A position of a bistable loop indicates that the nature of the switch is qualitatively different from that predicted by the plane wave analysis. It is shown that these differences result from self-focusing of the incident and reflected beams, their mutual cross-phase modulation and large nonspecular deformations of the reflected beam.