Generation of light in media with a random distribution of nonlinear domains

We show that the second order nonlinear generation of light, a process that it is assumed to require highly ordered materials, is also possible in structures of randomly oriented nonlinear domains. We explain theoretically why in such disordered structures the efficiency of the nonlinear generation of light grows linearly with the number of domains. Moreover, a higher degree of disorder, obtained when the dispersion is made very large, has no negative effect for the nonlinear light generation. In such conditions, light generation is shown to be equally efficient for any average size of the domains and also to grow linearly with respect to the number of domains.     

Generation of light of second harmonic frequency in a Gaussian light

The process of second harmonic frequency generation in a chaotic (Gaussian) light on the basis of a simple quantum-mechanical model is studied in this work. It is shown that the process of second harmonic frequency generation in the chaotic light is quicker than that in the coherent light with the Poisson distribution of photon number.     

Parametric generation of multipole radiation in a gas laser

The conditions are investigated for the resonant parametric generation of coherent electromagnetic multipole radiation in a gas laser amplifier by two light waves which interact with two coupled atomic transitions. Cross susceptibility tensors are derived within a semiclassical model taking the polarization of light and atoms into account. Doppler broadening restricts the generation to a difference frequency in a “folded” array of levels. In a specific example an intensity of 10^?10 W/mm² is estimated.     

Generation of nonclassical states of a field with frequency-dependent squeezing

The generation of nonclassical states of light with specified frequency-dependent squeezing by way of introducing a correlation between the phase and amplitude of the input field is considered. Three schemes for measuring amplitude fluctuations of the input beam, based on a nondemolition measurement of the intensity in a nonlinear cubic crystal, the effect of light rectification in a quadratic optical crystal, and the use of a non-degenerate optical parametric oscillator, are proposed. The maximum possible value of noise suppression is estimated for each scheme. The prospects for practical realization of the proposed method for generation of frequency-dependent squeezed states are discussed.     

Generation of Extremely Short Pulses upon Excitation of a Resonant Medium by a Superluminal Light Spot

The possibility of generation of quasi-unipolar extremely short pulses (with a duration of several periods of field oscillations) is theoretically analyzed for the excitation of a circular, nonlinear, and resonant medium with a light spot. The light spot rotates along a circle with a velocity that exceeds the speed of light in vacuum, while particles of the medium are distributed uniformly along the circle. It is shown that, by introducing a delay in the form of a phase plate into the system, one can control the shape, the duration, and the amplitude of generated pulses.     

A novel system of the simultaneous trapping of dark-bright solitons within a nano-waveguide system

We propose a novel system of a nano-waveguide that can be used to generate the continuous spectrum, i.e. white light. The simultaneous trapping and generation of short and millimeter waves can also be performed by using either bright or dark soliton. A system consists of two micro- and a nano-ring resonators that can be integrated into a single system. The large bandwidth is generated by a soliton pulse within a Kerr-type nonlinear medium where the continuous bandwidth or wavelength can be performed. The simultaneous dark-bright solitons conversion is performed and achieved. Results obtained have shown the potential of using the technique for continuing light spectra generation, where the filtering signals are allowed by using the suitable device parameters. The advantage is that the large bandwidth separation of the short and sub-millimeter waves can be obtained, which is allowed to form the simultaneous generation of short and millimeter waves within a single system. Further, light pulse can be trapped within a nano-waveguide, which is available to form the memory device.     

Photodynamic Therapy for Cancer Cells Using a Flash Wave Light Xenon Lamp

We determined photodynamic therapy (PDT) efficacy using a flash wave (FW) and a continuous wave (CW) light, of which the fluence rate was 70 W/cm², for murine thymic lymphoma cells (EL-4) cultivated in vitro. The irradiation frequency and the pulse width of the FW light were in the range of 1–32 Hz and less than one millisecond, respectively. 5-Aminolevulinic acid-induced protoporphyrin IX (ALA-PpIX) was used as a photosensitizer. When EL-4 with ALA administration was irradiated by the light for 4 h (irradiation fluence: 1.0J/cm²), the survival rate of EL-4 by the FW light was lower than that by the CW light, except for the FW light with irradiation frequency of 32 Hz, and decreased gradually with decreasing irradiation frequency. Moreover, the FW light, especially at lower irradiation frequency, was superior to the CW light for the generation of singlet oxygen in an aqueous PpIX solution. Therefore, thehigher PDT efficacy for EL-4 of the FW light would be caused by the greater generation of singlet oxygen in the cells.     

Theoretical analysis of the second-harmonic light power in a biaxial crystal

Theoretical analyses are presented on the critically phase-matched second-harmonic generation （SHG） in a biaxial crystal with the focused fundamental Gaussian beams. The dependence of the second-harmonic light power on the phase matching conditions, focused geometries, walk-off effects, and absorptions are discussed in detail. Expressions are presented for calculating the light power of the types I and II SHGs in the biaxial crystal, applied to optimize the blue light generation with the LiB305 crystal. A maximum conversion efficiency of around 37% is obtained with 798-nm laser power of 500 mW.     

Photonic generation of ultra-wideband doublet pulse using a semiconductor-optical-amplifier based polarization-diversified loop

We propose and demonstrate a novel scheme of ultra-wideband (UWB) doublet pulse generation using a semiconductor optical amplifier (SOA) based polarization-diversified loop (PDL) without any assistant light. In our scheme, the incoming gaussian pulse is split into two parts by the PDL, and each of them is intensity modulated by the other due to cross-gain modulation (XGM) in the SOA. Then, both parts are recombined with incoherent summation to form a UWB doublet pulse. Bi-polar UWB doublet pulse generation is demonstrated using an inverted gaussian pulse injection. Moreover, pulse amplitude modulation of UWB doublet is also experimentally demonstrated. Our scheme shows some advantages, such as simple implementation without assistant light and single optical carrier operation with good fiber dispersion tolerance.     

Nonlinear mixing between the emission of a cw laser and a femtosecond laser

We mix the emission of a femtosecond Ti:sapphire laser with the emission of a continuous wave infrared laser in a beta-barium borate crystal. Green light with a center wavelength of 527 nm and a spectral width of 2.5 nm resulting from sum frequency generation is detected. An intensity study verifies that a nonlinear χ⁽²⁾ process is at the origin of the green light generation. The experimentally obtained conversion efficiency of 7 × 10⁻¹⁰ is in good agreement to simple theoretical considerations.     

Manipulation of multi-transparency windows and fast-slow light transitions in a hybrid cavity optomechanical system

We study the generation of quadruple-transparency windows and the implementation of a conversion between slow and fast light in a hybrid optomechanical system. By demonstrating the generation of these transparency windows one by one, we analyze the physical mechanism through which each transparency window forms in detail. Additionally, we discuss how the system parameters affect the formation of transparency windows and conclude that the location, width, and absorption of each transparency window can be arbitrarily manipulated by varying the appropriate parameters. Moreover, when the pump field is changed from red to blue detuning, conversions between slow and fast light occur in the output field. These interesting properties of the output field can be applied to achieve the coherent control and manipulation of light pulses using cavity optomechanical system.     

Experimental investigation of a multichannel N2-laser

A multichannel UV-laser is described which provides a flexible high repetition rate pulsed light source for the generation of short duration light pulses.     

Spectroscopic polarimetry with a channeled spectrum

We describe a novel method for the spectroscopic measurement of the state of polarization (SOP) of light. A pair of thick birefringent retarders is incorporated into the spectroscopic polarimeter, so the generated channeled spectrum is composed of three quasi-cosinusoidal components carrying the information about the SOP of the light that is being measured. Fourier inversion of the channeled spectrum provides significant parameters for determination of the spectrally resolved Stokes parameters of light. No mechanically movable components for polarization control or active devices for polarization modulation are used, and all the Stokes parameters can be determined at once from only the single spectrum. The effectiveness of this method is demonstrated by the generation of elliptically polarized light whose SOP varies with wave number.     

Dynamics of the fields of counterpropagating light pulses of a few oscillations in nonlinear dielectric media

Evolution equations have been derived for the fields of counterpropagating light pulses of a few oscillations interacting with dielectric media with nonresonant dispersion and inertialess electron nonlinearity. Changes in the field structure and spectrum of a low-intensity pulse colliding with a high-intensity counterpropagating light pulse are illustrated. It has been shown that such a collision can be accompanied by the generation of radiation at multiple frequencies with a duration smaller than the durations of the initial pulses.     

Yellow light generation by frequency doubling of a diode-pumped Nd:YAG laser

We demonstrate the generation of TEM₀₀ mode yellow light in critically type II phase-matched KTiOPO₄ (KTP) with intracavity frequency doubling of a diode-pumped Nd:YAG laser at room temperature. After a 150 μm thick etalon have been inserted into the cavity, the stability and beam quality of the second harmonic generation (SHG) is enhanced. A continuous wave (CW) TEM₀₀ mode output power of 1.67 W at 556 nm is obtained at a pump level of 16 W. The total optical to optical conversion efficiency is about 10.44%. To the best of our knowledge, this is the first Watt-level yellow light generation by frequency doubling of Nd:YAG laser.     

Dynamics of high-power self-similar light pulses in a fiber laser with a carbon-nanotube saturable absorber

We present a numerical analysis of the dynamics of high-power self-similar light pulses in a fiber laser with a saturable absorber based on carbon nanotubes (CNTs). This analysis allows us to identify lasing regimes in a CNT-mode-locked ytterbium-fiber laser enabling the generation of self-similar linearly chirped light pulses with an energy up to 330 nJ, which can be compressed to a 210-fs transform-limited pulse width through linear chirp compensation in a pulse compressor. We show that, for typical parameters of a fiber laser, the bandwidth and the minimum transform-limited pulse width of a self-similar laser output are primarily limited by the small modulation depth of a CNT absorber.     

Generation of an attosecond X-ray pulse in a thin film irradiated by an ultrashort ultrarelativistic laser pulse

The possibility of generating an attosecond x-ray pulse in a thin solid-density plasma layer irradiated by a femtosecond laser pulse of ultrarelativistic intensity has been demonstrated in numerical simulation. Changes in the plasma layer parameters during the light pulse result in the generation of a wide, partly continuous radiation spectrum in the layer. The separation of limited parts in the reflected or transmitted light spectrum makes it possible to obtain isolated short electromagnetic pulses with an intensity reaching 1% of the exciting light intensity.     

Generation and optical display of a binary-sampled phase-only hologram

Past research has demonstrated that a phase-only hologram can be obtained by down-sampling the intensity image of the object scene prior to the generation of the hologram. In this Letter, we extend the method to the generation of binary phase-only holograms. A hologram derived with our proposed method is referred to as a binary-sampled phase-only hologram(BSPOH). Being different from the parent scheme, we have adopted an offaxis configuration in the generation of the BSPOH to avoid the quantization noise, the zeroth-order light, and the conjugate lights. An experimental evaluation reveals that the reconstructed image of the BSPOH is of good quality, and only contains slight amount of noise.     

Polarization Insensitive Wavelength Conversions by a LiNbO3 Waveguide Using a Multi-Ring Configuration

A novel configuration is proposed for polarization insensitive wavelength conversions using a LiNbO₃ waveguide with a periodically domain inverted structure. The proposed configuration consists of multiple rings, which are connected by a polarization sensitive wavelength converter such as the LiNbO₃ waveguide described. One ring containing a pump light source is used to pump the wavelength converter bidirectionally, while the other rings containing a polarization beam splitter and a 90° polarization rotator are used to couple in the input signal and extract the converted light. The proposed method is proven experimentally by the wavelength conversion based on sum frequency generation.