This paper presents a new design of Ge 20 Sb 5 Se 75 large-solid-core-square lattice photonic cry... more This paper presents a new design of Ge 20 Sb 5 Se 75 large-solid-core-square lattice photonic crystal fiber (PCF) with the first ring of air hole near the core removed. Using the full vector finite element method for anisotropic perfectly matched layers, we numerically examine the dispersion characteristics of the PCF as a function of the wavelength in the mid-infrared range. The results reveal that photonic crystal fibers exhibit a variety of dispersion properties, including all-normal and anomalous dispersion, featuring one or two zero dispersion wavelengths (ZDWs). Based on our numerical simulations, we propose two structures with optimal dispersion characteristics. These designs have small lattice constants (Λ = 1.0 µm; Λ = 1.5 µm) and low fill factors (d/Λ = 0.3; d/Λ = 0.35). These proposed PCFs could be candidates for many optical applications as supercontinuum generations source.
The microlens arrays created by ultrasonic waves in acousto-optical material Germanium (Ge) is th... more The microlens arrays created by ultrasonic waves in acousto-optical material Germanium (Ge) is theoretically proposed. The simulated results show the proposed microlens arrays can be used for optical tweezers arrays to trap an assembly micro-beads. Moreover, with the control by changing of the ultrasonic intensity and frequency, the optical tweezers arrays will act as the dynamical one, which can sieve the beads in (X,Y) plane in the embedding fluid.
We report a numerical study on mid-infrared (IR) supercontinuum (SC) generation in the regime of ... more We report a numerical study on mid-infrared (IR) supercontinuum (SC) generation in the regime of all normal dispersion using lead bismuth gallate glass photonic crystal fiber. This fiber allows the changing of dispersion from anomalous dispersion to ultra-flat normal dispersion in the wavelength range of over 930 nm by filling its cladding holes with C2Cl4. Using a 12.5 kW laser pulse at 2.8 µm as a pump source, we demonstrate that a broad and highly coherent SC generation spectrum is generated in the wavelength range of 1.2 μ m –3.4 μ m with the effects of vacuum noise. However, pulse-to-pulse relative intensity noise significantly decreases the coherence. These interesting optical properties make the proposed C2Cl4—infiltrated fiber highly promising for various applications in the mid-IR regime, particularly, spectroscopy, optical coherence tomography, and metrology.
This study shows that it is possible to achieve a very large supercontinuum spectral broadening w... more This study shows that it is possible to achieve a very large supercontinuum spectral broadening with a peak power hundreds of times lower than in previous publications. We can achieve by using a square lattice toluene-core photonic crystal fiber. With the heterogeneity in the diameter of air holes, our new design allows simultaneous optimization of characteristic quantities to ensure flat near-zero dispersion, small effective mode area, and low attenuation for efficient spectral broadening. Supercontinuum generation (SC) of proposed PCFs has been numerically simulated and studied under different pump source parameters. The first fiber with a lattice constant of 1.0 μm and filling factor of 0.65 operates in all-normal dispersion. It generates broadband of 1.045 μm by a pump pulse with a central wavelength of 1.3 μm, 40 fs duration, and energy of 18 pJ (corresponding peak power of 0.45 kW). Besides, two octave-spanning of the SC spectrum in the wavelength range of 0.775–4.3 μm are formed in the second fiber with an input pulse whose optical properties are 1.55 μm wavelength, 100 fs duration, and energy of 55 pJ (0.45 kW of the peak power). The lattice constant of second fiber is 2.0 μm and the filling factor is 0.3. They would be good candidates for all-fiber SC sources operating with low-power pump lasers. This would be a as cost-effective alternatives to glass core fibers.
In this study, we demonstrate the ability to generate a broad supercontinuum (SC) spectrum with a... more In this study, we demonstrate the ability to generate a broad supercontinuum (SC) spectrum with a low peak power of square (S-PCF) and circular (C-PCF) lattice photonic crystal fibers with hollow-core infiltrated with carbon tetrachloride (CCl4). The dispersion and nonlinear characteristics have been numerically analyzed in detail and compared to select the optimal structures for SC generation and evaluate the SC generation efficiency for each PCF. With four optimal proposed structures, the all-normal dispersion of square PCF (#SF1) is found to be flatter and smaller. This results in its SC bandwidth reaching 901 nm at 1.095 μm pumping wavelength which is broader than that of circular PCF (#CF1) (768 nm at 0.98 μm wavelength) despite the lower nonlinear coefficient and higher confinement loss. For the anomalous dispersion regime, #CF2 fiber provides a wider SC spectrum (1753.1 nm) with a peak power of 10 kW compared to #SF2 (1689.6 nm) with a peak power of 13.75 kW thanks to the higher nonlinear coefficient and smaller confinement loss. With the higher nonlinearity of CCl4, the proposed fibers can be a new generation of optical fibers, suitable for low peak power all-fiber optical systems replacing glass core fibers.
In this paper, we demonstrated the ability of a hexagonal photonic crystal fiber (PCF) with a hol... more In this paper, we demonstrated the ability of a hexagonal photonic crystal fiber (PCF) with a hollow core infiltrated with nitrobenzene (C6H5NO2) to generate a broad SC spectrum at low peak powers. Due to the non-uniformity of the air hole diameters, our new design allows for simultaneous optimization of features, resulting in near-flat, near-zero dispersion, a small effective mode area, and low attenuation for efficient spectral broadening. We selected two optimal structures from the simulation results to analyze the nonlinear properties and supercontinuum generation. The first fiber, #HF1, with a lattice constant of 1.0[Formula: see text][Formula: see text]m and a filling factor of 0.45, operates in all-normal dispersion and produces spectral SC ranging from 0.81[Formula: see text][Formula: see text]m to 1.919[Formula: see text][Formula: see text]m with a pump wavelength of 1.56[Formula: see text][Formula: see text]m, a pulse duration of 90[Formula: see text]fs, and peak power of 0.133[Formula: see text]kW propagated in a 1 cm fiber length. The #HF2 fiber (lattice constant of 2.0[Formula: see text][Formula: see text]m, filling factor of 0.3) has an extended SC spectrum from 0.792[Formula: see text][Formula: see text]m to 3.994[Formula: see text][Formula: see text]m, a pump wavelength of 1.55[Formula: see text][Formula: see text]m, a pulse width of 110[Formula: see text]fs, a peak power of 0.273[Formula: see text]kW propagated in a 15[Formula: see text]cm fiber length. The proposed fiber may be a new-generation optical fiber suitable for low-peak power all-fiber optical systems to replace glass-core glass fiber.
Electromagnetically induced transparency is observed in a mismatched-wavelength cascade system wi... more Electromagnetically induced transparency is observed in a mismatched-wavelength cascade system with a room-temperature rubidium vapor cell. A cw probe laser beam monitors the 5S 1͞2 3 5P 3͞2 transition while another cw laser couples the 5P 3͞2 state to a higher excited state. The ratio of the observed Rabi frequencies for coupling to the 5P 3͞2 3 8D 3͞2 , 5͞2 transitions agrees well with that predicted by use of the transition oscillator strengths. Optical switching is demonstrated with an 80-mW coupling laser beam modulated up to 1 MHz.
In our previous paper (DOAN QUOC K. et al., Physica Scripta T147, 2012, article 014008), electrom... more In our previous paper (DOAN QUOC K. et al., Physica Scripta T147, 2012, article 014008), electromagnetically induced transparency for Λ-like systems consisting of two lower bound states and a flat continuum coupled to an autoionization state embedded in it has been considered, in which the laser coupling light is modeled by white noise. In this paper, we investigate a similar scheme, where the continuum involved in the problem is replaced by one with so-called the double-Λ system, when instead of one autoionization state we have two autoionization states of the same energy embedded in the continuum. For such a system containing degenerate autoionization levels we derive a set of coupled stochastic integro-differential equations which can be averaged exactly. This leads to the exact formula determining the stationary solution for the electric susceptibility. Dispersion and absorption spectra for electromagnetically induced transparency are found and compared with those obtained previously by us and other authors.
This paper presents a new design of Ge 20 Sb 5 Se 75 large-solid-core-square lattice photonic cry... more This paper presents a new design of Ge 20 Sb 5 Se 75 large-solid-core-square lattice photonic crystal fiber (PCF) with the first ring of air hole near the core removed. Using the full vector finite element method for anisotropic perfectly matched layers, we numerically examine the dispersion characteristics of the PCF as a function of the wavelength in the mid-infrared range. The results reveal that photonic crystal fibers exhibit a variety of dispersion properties, including all-normal and anomalous dispersion, featuring one or two zero dispersion wavelengths (ZDWs). Based on our numerical simulations, we propose two structures with optimal dispersion characteristics. These designs have small lattice constants (Λ = 1.0 µm; Λ = 1.5 µm) and low fill factors (d/Λ = 0.3; d/Λ = 0.35). These proposed PCFs could be candidates for many optical applications as supercontinuum generations source.
The microlens arrays created by ultrasonic waves in acousto-optical material Germanium (Ge) is th... more The microlens arrays created by ultrasonic waves in acousto-optical material Germanium (Ge) is theoretically proposed. The simulated results show the proposed microlens arrays can be used for optical tweezers arrays to trap an assembly micro-beads. Moreover, with the control by changing of the ultrasonic intensity and frequency, the optical tweezers arrays will act as the dynamical one, which can sieve the beads in (X,Y) plane in the embedding fluid.
We report a numerical study on mid-infrared (IR) supercontinuum (SC) generation in the regime of ... more We report a numerical study on mid-infrared (IR) supercontinuum (SC) generation in the regime of all normal dispersion using lead bismuth gallate glass photonic crystal fiber. This fiber allows the changing of dispersion from anomalous dispersion to ultra-flat normal dispersion in the wavelength range of over 930 nm by filling its cladding holes with C2Cl4. Using a 12.5 kW laser pulse at 2.8 µm as a pump source, we demonstrate that a broad and highly coherent SC generation spectrum is generated in the wavelength range of 1.2 μ m –3.4 μ m with the effects of vacuum noise. However, pulse-to-pulse relative intensity noise significantly decreases the coherence. These interesting optical properties make the proposed C2Cl4—infiltrated fiber highly promising for various applications in the mid-IR regime, particularly, spectroscopy, optical coherence tomography, and metrology.
This study shows that it is possible to achieve a very large supercontinuum spectral broadening w... more This study shows that it is possible to achieve a very large supercontinuum spectral broadening with a peak power hundreds of times lower than in previous publications. We can achieve by using a square lattice toluene-core photonic crystal fiber. With the heterogeneity in the diameter of air holes, our new design allows simultaneous optimization of characteristic quantities to ensure flat near-zero dispersion, small effective mode area, and low attenuation for efficient spectral broadening. Supercontinuum generation (SC) of proposed PCFs has been numerically simulated and studied under different pump source parameters. The first fiber with a lattice constant of 1.0 μm and filling factor of 0.65 operates in all-normal dispersion. It generates broadband of 1.045 μm by a pump pulse with a central wavelength of 1.3 μm, 40 fs duration, and energy of 18 pJ (corresponding peak power of 0.45 kW). Besides, two octave-spanning of the SC spectrum in the wavelength range of 0.775–4.3 μm are formed in the second fiber with an input pulse whose optical properties are 1.55 μm wavelength, 100 fs duration, and energy of 55 pJ (0.45 kW of the peak power). The lattice constant of second fiber is 2.0 μm and the filling factor is 0.3. They would be good candidates for all-fiber SC sources operating with low-power pump lasers. This would be a as cost-effective alternatives to glass core fibers.
In this study, we demonstrate the ability to generate a broad supercontinuum (SC) spectrum with a... more In this study, we demonstrate the ability to generate a broad supercontinuum (SC) spectrum with a low peak power of square (S-PCF) and circular (C-PCF) lattice photonic crystal fibers with hollow-core infiltrated with carbon tetrachloride (CCl4). The dispersion and nonlinear characteristics have been numerically analyzed in detail and compared to select the optimal structures for SC generation and evaluate the SC generation efficiency for each PCF. With four optimal proposed structures, the all-normal dispersion of square PCF (#SF1) is found to be flatter and smaller. This results in its SC bandwidth reaching 901 nm at 1.095 μm pumping wavelength which is broader than that of circular PCF (#CF1) (768 nm at 0.98 μm wavelength) despite the lower nonlinear coefficient and higher confinement loss. For the anomalous dispersion regime, #CF2 fiber provides a wider SC spectrum (1753.1 nm) with a peak power of 10 kW compared to #SF2 (1689.6 nm) with a peak power of 13.75 kW thanks to the higher nonlinear coefficient and smaller confinement loss. With the higher nonlinearity of CCl4, the proposed fibers can be a new generation of optical fibers, suitable for low peak power all-fiber optical systems replacing glass core fibers.
In this paper, we demonstrated the ability of a hexagonal photonic crystal fiber (PCF) with a hol... more In this paper, we demonstrated the ability of a hexagonal photonic crystal fiber (PCF) with a hollow core infiltrated with nitrobenzene (C6H5NO2) to generate a broad SC spectrum at low peak powers. Due to the non-uniformity of the air hole diameters, our new design allows for simultaneous optimization of features, resulting in near-flat, near-zero dispersion, a small effective mode area, and low attenuation for efficient spectral broadening. We selected two optimal structures from the simulation results to analyze the nonlinear properties and supercontinuum generation. The first fiber, #HF1, with a lattice constant of 1.0[Formula: see text][Formula: see text]m and a filling factor of 0.45, operates in all-normal dispersion and produces spectral SC ranging from 0.81[Formula: see text][Formula: see text]m to 1.919[Formula: see text][Formula: see text]m with a pump wavelength of 1.56[Formula: see text][Formula: see text]m, a pulse duration of 90[Formula: see text]fs, and peak power of 0.133[Formula: see text]kW propagated in a 1 cm fiber length. The #HF2 fiber (lattice constant of 2.0[Formula: see text][Formula: see text]m, filling factor of 0.3) has an extended SC spectrum from 0.792[Formula: see text][Formula: see text]m to 3.994[Formula: see text][Formula: see text]m, a pump wavelength of 1.55[Formula: see text][Formula: see text]m, a pulse width of 110[Formula: see text]fs, a peak power of 0.273[Formula: see text]kW propagated in a 15[Formula: see text]cm fiber length. The proposed fiber may be a new-generation optical fiber suitable for low-peak power all-fiber optical systems to replace glass-core glass fiber.
Electromagnetically induced transparency is observed in a mismatched-wavelength cascade system wi... more Electromagnetically induced transparency is observed in a mismatched-wavelength cascade system with a room-temperature rubidium vapor cell. A cw probe laser beam monitors the 5S 1͞2 3 5P 3͞2 transition while another cw laser couples the 5P 3͞2 state to a higher excited state. The ratio of the observed Rabi frequencies for coupling to the 5P 3͞2 3 8D 3͞2 , 5͞2 transitions agrees well with that predicted by use of the transition oscillator strengths. Optical switching is demonstrated with an 80-mW coupling laser beam modulated up to 1 MHz.
In our previous paper (DOAN QUOC K. et al., Physica Scripta T147, 2012, article 014008), electrom... more In our previous paper (DOAN QUOC K. et al., Physica Scripta T147, 2012, article 014008), electromagnetically induced transparency for Λ-like systems consisting of two lower bound states and a flat continuum coupled to an autoionization state embedded in it has been considered, in which the laser coupling light is modeled by white noise. In this paper, we investigate a similar scheme, where the continuum involved in the problem is replaced by one with so-called the double-Λ system, when instead of one autoionization state we have two autoionization states of the same energy embedded in the continuum. For such a system containing degenerate autoionization levels we derive a set of coupled stochastic integro-differential equations which can be averaged exactly. This leads to the exact formula determining the stationary solution for the electric susceptibility. Dispersion and absorption spectra for electromagnetically induced transparency are found and compared with those obtained previously by us and other authors.
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