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22 results on '"Apurv Chaitanya N"'

6. Type-I frequency-doubling characteristics of high-power, ultrafast fiber laser in thick BIBO crystal

Author

Ravindra Pratap Singh, A. Aadhi, Apurv Chaitanya N, and G. K. Samanta

Subjects
Birefringence, Materials science, business.industry, Energy conversion efficiency, Second-harmonic imaging microscopy, Laser, Atomic and Molecular Physics, and Optics, law.invention, Laser linewidth, Optics, law, Fiber laser, BIBO stability, business, Ultrashort pulse
Abstract

We report on experimental realization of optimum focusing condition for type-I second-harmonic generation (SHG) of high-power, ultrafast laser in "thick" nonlinear crystal. Using single-pass, frequency doubling of a 5 W Yb-fiber laser of pulse width ~260 fs at repetition rate of 78 MHz in a 5-mm-long bismuth triborate (BIBO) crystal we observed that the optimum focusing condition is more dependent on the birefringence of the crystal than its group-velocity mismatch (GVM). A theoretical fit to our experimental results reveals that even in the presence of GVM, the optimum focusing condition matches the theoretical model of Boyd and Kleinman, predicted for continuous-wave and long-pulse SHG. Using a focusing factor of ξ=1.16 close to the estimated optimum value of ξ=1.72 for our experimental conditions, we generated 2.25 W of green radiation of pulse width 176 fs with single-pass conversion efficiency as high as 46.5%. Our study also verifies the effect of pulse narrowing and broadening of angular phase-matching bandwidth of SHG at tighter focusing. This study signifies the advantage of SHG in "thick" crystal in controlling SH-pulse width by changing the focusing lens while accessing high conversion efficiency and broad angular phase-matching bandwidth.

Published
2015

7. Generation and Characterization of High Power and Higher Order Ultrafast Optical Vortices

Author

M. V. Jabir, N. U. Shaikh, G. K. Samanta, Apurv Chaitanya N, M. R. Pathak, and A. Aadhi

Subjects
Physics, Maximum power principle, business.industry, Physics::Optics, Power (physics), Vortex, Crystal, Optics, Condensed Matter::Superconductivity, Light beam, BIBO stability, business, Ultrashort pulse, Optical vortex
Abstract

We report on generation of high-power and high-order ultrafast optical vortex beams. Frequency-doubling of optical vortices at 1064nm in BIBO crystal, we have generated vortices of maximum power and order of ~900mW and 12 respectively.

Published
2015

8. Frequency-Doubling of Femtosecond Pulses in “Thick” Nonlinear Crystals With Different Temporal and Spatial Walk-Off Parameters

Author

Universitat Politècnica de Catalunya. Institut de Ciències Fotòniques, Apurv Chaitanya, N., Aadhi, A., Chaitanya Kumar, S., Jabir, M. V., Samanta, G. K., Ebrahim-Zadeh, Majid, Universitat Politècnica de Catalunya. Institut de Ciències Fotòniques, Apurv Chaitanya, N., Aadhi, A., Chaitanya Kumar, S., Jabir, M. V., Samanta, G. K., and Ebrahim-Zadeh, Majid

Abstract

We present a comparative study on frequency-doubling characteristics of femtosecond laser pulses in thick nonlinear crystals with different temporal and spatial walk-off parameters. Using single-pass second harmonic generation (SHG) of 260 fs pulses at 1064 nm from a high-average-power femtosecond Yb-fiber laser in 5-mm-long crystals of β-BaB2O4 (BBO) and BiB3O6 (BIBO), we find that for comparable values of temporal and spatial walk-off parameters in each crystal, the optimum focusing condition for SHG is more strongly influenced by spatial walk-off than temporal walk-off. It is also observed that under such conditions, the Boyd and Kleinman theory commonly used to define the optimum focusing condition for frequency-doubling of cw and long-pulse lasers is also valid for SHG of ultrafast lasers. We also investigate the effect of focusing on the spectral, temporal, and spatial characteristics of the second harmonic (SH) radiation, as well as angular acceptance bandwidth for the SHG process, under different temporal and spatial walk-off conditions in the two crystals, Peer Reviewed, Postprint (author's final draft)

Published
2016

20. High-Power, Continuous-wave, Source Of Coherent Radiation In 2-D Airy Intensity Distribution

Author

Pravin Vaity, Apurv Chaitanya N, A. Aadhi, R.P. Singh, G. K. Samanta, and M. V. Jabir

Subjects
Physics, Spatial filter, business.industry, Airy beam, Physics::Optics, Radiation, Beam parameter product, Intensity (physics), Optics, Physics::Accelerator Physics, Continuous wave, M squared, Laser beam quality, business
Abstract

We demonstrate a new class of tunable Airy beam source based on OPO, producing high-power, continuous-wave, single-frequency Airy beam radiation. The source provides total tunability of 460nm and maximum of 8.1W in 2D-Airy beam structure.

21. Continuous-wave, high power, single-frequency, tunable ultraviolet source based on all periodically poled crystals

Author

A. Aadhi, Apurv Chaitanya N, Ravindra Pratap Singh, and G. K. Samanta

Subjects
3D optical data storage, Materials science, Sum-frequency generation, business.industry, Physics::Optics, Radiation, medicine.disease_cause, Nonlinear optical crystal, Power (physics), Optics, medicine, Optical parametric oscillator, Optoelectronics, Continuous wave, business, Ultraviolet
Abstract

We report on all periodically-poled crystals based singly-resonant optical parametric oscillator (SRO) generating continuous-wave, single-frequency, tunable UV radiation with maximum output power of 336mW in 18.5 MHz line-width at 399.2nm. It has tunability of 18nm.

22. High-power, continuous-wave, solid-state, single-frequency, tunable source for the ultraviolet.

Author

Aadhi A, Apurv Chaitanya N, Singh RP, and Samanta GK

Subjects
Equipment Design, Lasers, Solid-State, Optical Phenomena, Oscillometry instrumentation, Optical Devices, Ultraviolet Rays
Abstract

We report the development of a compact, high-power, continuous-wave, single-frequency, ultraviolet (UV) source with extended wavelength tunability. The device is based on single-pass, intracavity, second-harmonic-generation (SHG) of the signal radiation of a singly resonant optical parametric oscillator (SRO) working in the visible and near-IR wavelength range. The SRO is pumped in the green with a 25-mm-long, multigrating, MgO doped periodically poled stoichiometric lithium tantalate (MgO:sPPLT) as nonlinear crystal. Using three grating periods, 8.5, 9.0, and 9.5 μm of the MgO:sPPLT crystal and a single set of cavity mirrors, the SRO can be tuned continuously across 710.7-836.3 nm in the signal and corresponding idler across 2115.8-1462.1 nm with maximum idler power of 1.9 W and maximum out-coupled signal power of 254 mW. By frequency-doubling the intracavity signal with a 5-mm-long bismuth borate (BIBO) crystal, we can further tune the SRO continuously over 62.8 nm across 355.4-418.2 nm in the UV with maximum single-frequency UV power, as much as 770 mW at 398.28 nm in a Gaussian beam profile. The UV radiation has an instantaneous line-width of ∼14.5  MHz and peak-peak frequency stability of 151 MHz over 100 s. More than 95% of the tuning range provides UV power >260  mW. Access to lower UV wavelengths can in principle be realized by operating the SRO in the visible using shorter grating periods.

Published
2014
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