The Experts below are selected from a list of 2004 Experts worldwide ranked by ideXlab platform
Raymond K. Kostuk - One of the best experts on this subject based on the ideXlab platform.
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Enhanced phase shift in a zeroth-order beam from subwavelength Grating structures formed in uniaxial birefringent materials
Journal of the Optical Society of America A, 1996Co-Authors: Chien Wei Han, Raymond K. KostukAbstract:A subwavelength Grating structure made in an isotropic medium induces form birefringence effects, and the artificially produced optical axis is parallel to the Grating Vector. The phase shift between the two orthogonal electric-field components exiting this Grating varies linearly with the thickness of the Grating. When a Grating with subwavelength period is formed on a uniaxial birefringent material with the Grating Vector aligned parallel to its natural optical axis, the total effect enhances the birefringence of the material. As a result, the thickness of the material can be reduced and still produce the same phase shift. If the natural optical axis and the induced optical axis lie within the surface plane and have an angular separation between them, the phase shift varies nonlinearly with the thickness of the Grating.
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Enhanced birefringence effects from subwavelength Grating structures formed in uniaxial birefringent materials
Application and Theory of Periodic Structures, 1995Co-Authors: Chien Wei Han, Raymond K. KostukAbstract:Sub-wavelength Grating structures made in an isotropic medium induce form birefringence effects with the induced optical axis parallel to the Grating Vector. The phase shift between the two orthogonal electric field components exiting this Grating varies linearly with the thickness of the Grating. When a Grating with sub-wavelength period is formed on a uniaxial birefringent material with the Grating Vector aligned parallel to is natural optical axis, the total effect is enhanced birefringence for the material. Smaller thickness of the material is required to achieve the same phase shift. If the natural optical axis and the induced optical axis lie within the surface plane and have an angle between them, the phase shift varies nonlinearly with the thickness of the Grating.
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Diffractive-optic polarization-sensing element for magneto-optic storage heads.
Optics letters, 1994Co-Authors: Raymond K. Kostuk, Tae-jin Kim, Gene Campbell, C W HanAbstract:A cascaded planarized holographic optical sensor consisting of a combination of a leaky beam splitter and a polarization beam splitter is evaluated for possible use in magneto-optic data storage pickup heads. The performance requirements for each element are specified, and two cascaded Grating designs are considered. In one design we reconstruct the Gratings with the Grating Vector in the plane of incidence, using a half-wave plate. In the second design we reconstruct the Gratings with the Grating Vector of the polarization beam splitter out of the plane of incidence without using a half-wave plate. The two systems are fabricated with Gratings formed in dichromated gelatin emulsions, and they can detect 0.5 degrees rotations in the polarization state of an incident beam by use of a differential detection system.
Leonid B. Glebov - One of the best experts on this subject based on the ideXlab platform.
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Effect of aberrations in a holographic system on reflecting volume Bragg Gratings.
Applied optics, 2013Co-Authors: Marc Segall, Daniel Ott, Ivan Divliansky, Leonid B. GlebovAbstract:The effect of aberrations in the recording beams of a holographic setup is discussed regarding the deterioration of properties of a reflecting volume Bragg Grating. Imperfect recording beams result in a spatially varying Grating Vector, which causes broadening, asymmetry, and washed out side lobes in the reflection spectrum as well as a corresponding reduction in peak diffraction efficiency. These effects are more significant for Gratings with narrower spectral widths.
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Non-collinear generation of third harmonic of IR ultrashort laser pulses by PTR glass volume Bragg Gratings.
Optics express, 2009Co-Authors: Leo A. Siiman, Julien Lumeau, Lionel Canioni, Leonid B. GlebovAbstract:Three conditions for non-collinear third harmonic generation by a PTR glass volume Bragg Grating are demonstrated using infrared ultrashort pulse illumination. Each condition corresponds to a different angle of Grating orientation and a separate generation mechanism. We identify the mechanisms as corresponding to sum-frequency generation, Bragg diffraction of 3ω, and a non-resonant Bragg condition involving three ω photons interacting with a nonlinear Grating Vector. Theoretical modeling is performed using wave Vector additions and the results are compared to experimental measurements.
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Non-collinear generation of third harmonic of IR ultrashort laser pulses by PTR glass volume Bragg Gratings
Optics Express, 2009Co-Authors: Leo A. Siiman, Julien Lumeau, Lionel Canioni, Leonid B. GlebovAbstract:Three conditions for non-collinear third harmonic generation by a PTR glass volume Bragg Grating are demonstrated using infrared ultrashort pulse illumination. Each condition corresponds to a different angle of Grating orientation and a separate generation mechanism. We identify the mechanisms as corresponding to sum-frequency generation, Bragg diffraction of 3 omega, and a non-resonant Bragg condition involving three. photons interacting with a nonlinear Grating Vector. Theoretical modeling is performed using wave Vector additions and the results are compared to experimental measurements
Chien Wei Han - One of the best experts on this subject based on the ideXlab platform.
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Enhanced phase shift in a zeroth-order beam from subwavelength Grating structures formed in uniaxial birefringent materials
Journal of the Optical Society of America A, 1996Co-Authors: Chien Wei Han, Raymond K. KostukAbstract:A subwavelength Grating structure made in an isotropic medium induces form birefringence effects, and the artificially produced optical axis is parallel to the Grating Vector. The phase shift between the two orthogonal electric-field components exiting this Grating varies linearly with the thickness of the Grating. When a Grating with subwavelength period is formed on a uniaxial birefringent material with the Grating Vector aligned parallel to its natural optical axis, the total effect enhances the birefringence of the material. As a result, the thickness of the material can be reduced and still produce the same phase shift. If the natural optical axis and the induced optical axis lie within the surface plane and have an angular separation between them, the phase shift varies nonlinearly with the thickness of the Grating.
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Enhanced birefringence effects from subwavelength Grating structures formed in uniaxial birefringent materials
Application and Theory of Periodic Structures, 1995Co-Authors: Chien Wei Han, Raymond K. KostukAbstract:Sub-wavelength Grating structures made in an isotropic medium induce form birefringence effects with the induced optical axis parallel to the Grating Vector. The phase shift between the two orthogonal electric field components exiting this Grating varies linearly with the thickness of the Grating. When a Grating with sub-wavelength period is formed on a uniaxial birefringent material with the Grating Vector aligned parallel to is natural optical axis, the total effect is enhanced birefringence for the material. Smaller thickness of the material is required to achieve the same phase shift. If the natural optical axis and the induced optical axis lie within the surface plane and have an angle between them, the phase shift varies nonlinearly with the thickness of the Grating.
M. Segev - One of the best experts on this subject based on the ideXlab platform.
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Electroholographic tunable volume Grating in the g44 configuration.
Optics letters, 2006Co-Authors: Assaf Bitman, Lavi Secundo, Guy Bartal, Noam Sapiens, Aharon J. Agranat, M. SegevAbstract:The g(44) Grating is an electroholographic transmission Grating in which the applied field is perpendicular to both the Grating Vector and the wave Vector of the incident beam. It is argued that in this configuration the incident beam traverses through a periodically rotating index ellipsoid. It is shown that in the g(44) configuration the Bragg condition is fulfilled for a specific value of the applied field and for a diffracting beam polarization that is perpendicular to that of the incident beam. Consequently, the g(44) Grating can be used as an electrically controlled filter. Tunability of 7 nm is demonstrated in a 2mm thick Grating.
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Electroholographic tunable wavelength selective switch
2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006Co-Authors: Lavi Secundo, Guy Bartal, Assaf Bitman, Noam Sapiens, M. Segev, Aharon J. AgranatAbstract:Electroholographic switches in which the applied field is perpendicular to the Grating Vector so that the Bragg condition is electrically tuned are presented. Tunability of 7 nm can be accomplished in a single Grating.
Jacques Albert - One of the best experts on this subject based on the ideXlab platform.
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VCSEL-powered and polarization-maintaining fiber-optic Grating Vector rotation sensor.
Optics express, 2013Co-Authors: Tuan Guo, Bai-ou Guan, Fu Liu, Zhaochuan Zhang, Jacques AlbertAbstract:A compact fiber-optic Vector rotation sensor in which a short section of polarization-maintaining (PM) fiber stub containing a straight fiber Bragg Grating (FBG) is spliced to another single mode fiber without any lateral offset is proposed and experimentally demonstrated. Due to the intrinsic birefringence of the PM fiber, two well-defined resonances (i.e. orthogonally polarized FBG core modes) with wavelength separation of 0.5 nm have been achieved in reflection, and they exhibit a high sensitivity to fiber rotation. Both the orientation and the angle of rotation can be determined unambiguously via simple power detection of the relative amplitudes of the orthogonal core reflections. Meanwhile, instead of using a broadband source (BBS), the sensor is powered by a commercial vertical cavity surface emitting laser (VCSEL) with the laser wavelength matched to the PM-FBG core modes, which enables the sensor to work at much higher power levels (~15 dB better than BBS). This improves the signal-to-noise ratio considerably (~50 dB), and makes a demodulation filter unnecessary. Vector rotation measurement with a sensitivity of 0.09 dB/deg has been achieved via cost-effective single detector real time power measurement, and the unwanted power fluctuations and temperature perturbations can be effectively referenced out.
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Polarization-maintaining fiber-optic-Grating Vector vibroscope
Optics Letters, 2013Co-Authors: Tuan Guo, Libin Shang, Chuang Wu, Bai-ou Guan, Hwa-yaw Tam, Fu Liu, Jacques AlbertAbstract:A fiber-optic Vector vibroscope based on orthogonal polarization cladding-to-core recoupling is demonstrated. A compact structure in which a short section of polarization-maintained (PM) fiber stub containing a straight fiber Bragg Grating (FBG) is spliced to another single-mode fiber. Two well-defined orthogonally polarized cladding modes reflected by the PM-FBG are recoupled at the junction and the coupling intensity shows an extremely high sensitivity to bending in the corresponding orthogonal directions. Both the orientation and amplitude of the vibrations can be determined unambiguously via dual-path power detection of these recoupled orthogonal-polarimetric cladding modes (LP1;12 and LP1;13). Since spectral information is not required, temperature changes do not affect the sensor response, and power fluctuations can be referenced out by monitoring the power in the core mode (LP0;1) resonance.
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two dimensional fiber optic Vector vibroscope using only one multi mode tilted fiber Grating
OFS2012 22nd International Conference on Optical Fiber Sensors, 2012Co-Authors: Tuan Guo, Bai-ou Guan, Yang Ran, Yannan Tan, Shuai Gao, Lipeng Sun, Jacques AlbertAbstract:Orientation-recognized two-dimensional vibration sensor based on a polarization-controlled cladding-to-core recoupling is demonstrated experimentally. A compact structure in which a short section of multi-mode fiber stub containing a weakly tilted fiber Bragg Grating (TFBG) is spliced to another single-mode fiber without any lateral offset. Several well defined lower-order cladding resonances in reflection show different polarization dependence due to the tilted Grating Vector excitation. Both orientation and amplitude of the vibration can be determined unambiguously via dual-path power detection of the orthogonal-polarimetric odd-cladding-modes. Meanwhile, the unwanted power fluctuations and temperature perturbations can be definitely removed via core mode monitoring.
