Optical Terahertz Sources Based on Difference Frequency Generation in Nonlinear Crystals

Liu, Yang; Zhong, Kai; Wang, Aiqiang; Zhou, Ming; Li, Shanchuang; Zhang, Ze

doi:10.3390/cryst12070936

Cited by 14 publications

(10 citation statements)

References 107 publications

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“…Difference frequency generation (DFG) is a nonlinear optical process used to generate light at wavelengths that are not readily available from standard laser sources [16]. DFG is typically employed to create specific wavelengths in the mid-infrared (IR) or terahertz (THz) regions.…”

Section: Difference Frequency Generationmentioning

confidence: 99%

Prediction of Transmittance for a Free Space Quantum Channel and Improving Quantum Keyrate in Adverse Atmospheric Condition

Choudhury,

Nandi

2024

Preprint

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Free Space Optical Quantum Communication (FSOQC) is a new wireless approach that allows users to communicate in a secure and faster manner. The working mode of quantum communication is based on quantum physics and is somewhat probabilistic in nature. In order to carry quantum signal in a scattered environment, it is needed to derive the probability distribution of transmittance for a specified region at a desired communication link distance. To understand the performance of FSOQC under adverse weather condition, the effects of various atmospheric parameters such as fog, rain, and turbulence need to be analyzed. In the present study, an attempt is made to predict transmittance for a tropical location, Kolkata, India in real-time conditions, and Keyrate is estimated based on the predicted transmittance. The diurnal, monthly and yearly variation of transmittance is analyzed which is required for effective implementation of a quantum communication system. Two alternative situations, with and without sunlight are considered for Keyrate computation. A combination of two techniques, Difference Frequency Generation and Spontaneous Parametric Down Conversion has been applied to increase Keyrate under adverse weather condition. The operating wavelength is 800 nm, and combined technique is developed around that wavelength.

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Section: Difference Frequency Generationmentioning

confidence: 99%

Prediction of Transmittance for a Free Space Quantum Channel and Improving Quantum Keyrate in Adverse Atmospheric Condition

Choudhury,

Nandi

2024

Preprint

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“…Figure 6 shows the curve of coherence length of GaSe: S which was measured using equation (8). The value of coherence length is of the order of 1.37 mm at 0.33 THz which is sufficient enough to generate powerful THz radiation from the sample.…”

Section: Measurement Of Coherence Length and Thz Generation Efficiencymentioning

confidence: 99%

“…In addition, the presence of water molecules in the atmosphere contributes to strong absorption in certain bands of generated frequency [4][5][6]. A large number of semiconductors, organic and inorganic nonlinear crystals are evaluated for the THz generation using different types of optical techniques such as ultrafast switching in Photoconductive antennas, Difference Frequency Mixing (DFM) and Optical Rectification (OR) in ZnTe, GaAs, ZnGeP 2 , DAST, BNA, OH1 ,CdTe crystals and thin films [6][7][8][9][10][11][12][13][14].6-14. Vicario, C et al groups investigated the high-field THz generation in organic crystals DSTMS, DAST, and OH1 by optical rectification process using femtosecond Cr: fosterite laser pulse at 10 Hz repetition and they have achieved maximum conversion efficiency as high as 3% which corresponds to energy per pulse up to 270 μJ [15].…”

Section: Introductionmentioning

confidence: 99%

Comparative studies of terahertz-based optical properties in transmission/reflection modes of GaSe: S and measurement of its scattering losses due to surface roughness for efficient terahertz generation

Ghorui¹,

Arjun²,

Kumar³

et al. 2023

Phys. Scr.

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The paper reports the efficient terahertz generation using nonlinear optical rectification process and comparative studies of optical, dielectric, and surface scattering properties of 1.0 mm thin GaSe: S crystal in transmission/reflection modes. We employed 800 nm wavelength of 140 fs and 50 fs pulse durations obtained from Ti: Sapphire oscillator and amplifier systems at 80 MHz and 1 kHz repetition rates, respectively, and evaluated the THz generation potential and optical properties such as refractive index, absorption coefficients, relative permittivity in transmission mode. In the next step, the crystal was subjected to a commercial THz system of 0.3 picosecond pulses at 100 MHz repetition rate in reflection geometry and once again recorded the similar parameters and compared with the transmission mode data. In addition, these data were used to measure the scattering losses from the surface of the crystal in terms of surface roughness, optical impedance, and Fresnel’s reflection coefficients. The maximum generated THz power was of the order of 4.5 μW with conversion efficiency (η) ~2.2 x 10-3%. The measured THz efficiency was found equivalent to 20 mm thick GaSe crystal used in the difference frequency mixing technique. Finally, we have measured the Rayleigh roughness factor (g) of the crystal surface at different THz frequencies. When g < 1 (for small roughness) the Fresnel reflection loss factor becomes 0.75 at 1.4 THz frequency range which helps to enhance the generated signal.

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“…As the core component of all solid-state lasers, nonlinear optical (NLO) crystals can obtain the desired laser frequency by using NLO technologies such as sum frequency generation (SFG), difference frequency generation (DFG), and optical parametric oscillation (OPO) [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. At present, NLO materials have been widely used in military and civil fields, including the development of laser radar, laser ranging, environmental monitoring, medical treatment, medical diagnosis, etc.…”

Section: Introductionmentioning

confidence: 99%

The Kurtz–Perry Powder Technique Revisited: A Study of the Effect of Reference Selection on Powder Second-Harmonic Generation Response

2023

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The accurate evaluation of nonlinear optical (NLO) coefficient, the main parameter affecting light conversion efficiency, plays a crucial role in the development of NLO materials. The Kurtz–Perry powder technique can evaluate second-harmonic generation (SHG) intensity in pristine powder form, saving a significant amount of time and energy in the preliminary screening of materials. However, the Kurtz–Perry method has recently been subject to some controversy due to the limitations of the Kurtz–Perry theory and the oversimplified experimental operation. Therefore, it is very meaningful to revisit and develop the Kurtz–Perry technique. In this work, on the basis of introducing the light scattering effect into the original Kurtz–Perry theory, the theoretical expression of second-harmonic generation intensity with respect to band gap and refractive index are analyzed. In addition, the reference-dependent SHG measurements were carried out on polycrystalline LiB3O5 (LBO), AgGaQ2 (Q = S, Se), BaGa4Q7 (Q = S, Se), and ZnGeP2 (ZGP), and the results of SHG response emphasize the importance of using appropriate references to the Kurtz–Perry method. In order to obtain reliable values of nonlinear coefficients, two criteria for selecting a reference compound were proposed: (1) it should possess a band gap close to that of the sample to be measured and (2) it should possess a refractive index close to that of the sample to be measured. This work might shed light on improvements in accuracy that can be made for effective NLO coefficients obtained using the Kurtz–Perry method.

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Optical Terahertz Sources Based on Difference Frequency Generation in Nonlinear Crystals

Cited by 14 publications

References 107 publications

Prediction of Transmittance for a Free Space Quantum Channel and Improving Quantum Keyrate in Adverse Atmospheric Condition

Prediction of Transmittance for a Free Space Quantum Channel and Improving Quantum Keyrate in Adverse Atmospheric Condition

Comparative studies of terahertz-based optical properties in transmission/reflection modes of GaSe: S and measurement of its scattering losses due to surface roughness for efficient terahertz generation

The Kurtz–Perry Powder Technique Revisited: A Study of the Effect of Reference Selection on Powder Second-Harmonic Generation Response

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