Nonlinear refractive index measuring using a double-grating interferometer in pump–probe configuration and Fourier transform analysis

Rasouli, Saifollah; Ghorbani, Mahnaz

doi:10.1088/2040-8978/14/3/035203

Cited by 16 publications

(8 citation statements)

References 22 publications

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“…The optical Kerr effect is a phenomenon where the refractive index of the medium is changed when an intense beam of light passes through it [14,15]. Most nano fluids have been reported to exhibit strong optical Kerr effects, such as self-focusing/de-focusing and spatial self-phase modulation (SSPM).…”

Section: Introductionmentioning

confidence: 99%

Vortex phase deterioration common-path interferometry

Shetty

Hemalatha

Babu

et al. 2023

J. Opt.

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Common path interferometers (CPI) are significant due to their compactness and vibration resistance. The usual challenge in CPI would arise due to a very small separation between reference and sample beams, where sending a reference beam through a sample is considered as a limitation. But this limitation also makes it difficult to probe the interaction of beams with material as a function of their phase structure. This study can pave the way for a new kind of interferometry that can provide unique phase signatures to study the sample. The paper proposes and demonstrates a novel approach based on thermo-optic refraction, to send both beams through the sample and probe the phase deterioration due to the relative interaction of beams in the material medium. Here, thermo-optic refraction interferometry (TORI) allows the superposition of a higher order vortex beam with a non-vortex beam through the phenomenon of thermal lensing. The non-vortex beam is made to expand in a controlled fashion by another laser. The relative interaction of the expanding non-vortex beam and the vortex beam within the sample, results in the output interferogram. The phase deterioration analysis of the output interferogram elucidate medium driven phase changes. This technique is demonstrated using the milk samples by recording the RMS azimuthal phase deterioration of the OAM beam.

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Section: Introductionmentioning

confidence: 99%

Vortex phase deterioration common-path interferometry

Shetty

Hemalatha

Babu

et al. 2023

J. Opt.

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“…Various techniques to measure the non-linear index of a medium have been proposed including methods based on beam-deflection [16,17,18], z-scan transmission [19,20,21] and ring patterns in far-field imaging [22,9]. However, all these techniques suffer from limitations either in the applicability, the simplicity of implementation or the precision.…”

Section: Introductionmentioning

confidence: 99%

Transit effects for non-linear index measurement in hot atomic vapors

Aladjidi¹,

Abuzarli²,

Brochier³

et al. 2022

Preprint

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Hot atomic vapors are widely used in non-linear and quantum optics due to their large Kerr non-linearity. While the linear refractive index and the transmission are precisely measured and well modeled theoretically, similar characterization remains partial for the χ (3) non-linear part of the susceptibility. In this work, we present a set of tools to measure and estimate numerically the non-linear index of hot atomic vapors both in the steady state and during the transient response of the medium. We apply these techniques for the characterization of a hot vapor of rubidium and we evidence the critical role played by transit effects, due to finite beam sizes, in the measurement of the non-linear index.

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“…In this paper, we propose a method to circumvent these requirements based on a THz referenceless shear interferometer realized by a THz RPG between the THz source and the camera sensor. In analogy to grating-based shear interferometers realized in visible range, 31 , 32 the RPG 33 acts as a shearing element that generates two diffraction orders, thereby, creating two laterally shifted images in the sensor plane. The direction of the shear can be varied by rotating the grating.…”

Section: Introductionmentioning

confidence: 99%

Characterization of terahertz wavefront aberrations using computational shear-interferometry

et al. 2022

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.We propose a new solution for sensing a terahertz (THz) wavefront based on a THz reference-less shear interferometer. The key component of the experimental configuration of the proposed interferometer is a THz Ronchi phase grating (RPG). The RPG is custom designed and fabricated for a 0.28 THz source using mechanical milling on a block of high-density polyethylene with a computer numerical control machine. It acts as a shearing element that generates two diffraction orders, thereby, creating two laterally shifted copies of the investigated wavefront in the sensor plane where a THz camera is placed. The direction of the shear can be varied by rotating the grating. Since the grating is a phase grating, the diffraction efficiency is very high. The approach is verified experimentally by demonstrating interferograms of a spherical wave and wavefront reconstruction from five different shears using a gradient-based iterative process.

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Nonlinear refractive index measuring using a double-grating interferometer in pump–probe configuration and Fourier transform analysis

Cited by 16 publications

References 22 publications

Vortex phase deterioration common-path interferometry

Vortex phase deterioration common-path interferometry

Transit effects for non-linear index measurement in hot atomic vapors

Characterization of terahertz wavefront aberrations using computational shear-interferometry

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