@sjec.ac.in
Associate Professor and Head
St Joseph Engineering College Mangaluru
MSc, MIT, PhD
Nonlinear Optical Materials, Z-Scan, Thin films, Crystal Growth
Scopus Publications
L. M. Clavian, P. C. Rajesh Kumar, K. V. Anil Kumar, D. Narayana Rao, N. K. Shihab, and Ganesh Sanjeev
American Chemical Society (ACS)
L.M. Clavian, K.V. Anil Kumar, D. Narayana Rao, N.K. Shihab, Ganesh Sanjeev, and P.C. Rajesh Kumar
Elsevier BV
Sandhya Dass, Ramananda H. S., Jagadeesha B., Rajesh Kumar P. C., and Reni K. K Cherian
Rajarambapu Institute of Technology
L.M. Clavian, P.C. Rajesh Kumar, K.V. Anil Kumar, D. Narayana Rao, N.K. Shihab, and Sanjeev Ganesh
Elsevier BV
L. M. Clavian, P. C. Rajesh Kumar, K. V. Anil Kumar, D. Narayana Rao, N. K. Shihab, and Ganesh Sanjeev
AIP Publishing
P. C. Rajesh Kumar, L. M. Clavian, K. V. Anil Kumar, D. Narayana Rao, N. K. Shihab, and Ganesh Sanjeev
AIP Publishing
The third order nonlinear optical properties of 5,10,15,20 Tetraphenyl 21H,23H-porphine zinc (II) (ZnTPP) thin films have been investigated by using single beam Z-scan technique with 6 ns laser pulse operating at 532 nm. The ultrathin films of ZnTPP with the thickness of the order of 120 nm were fabricated by means thermal vacuum coating technique. The UV-Visible spectrum depicts signature absorption curve identifying the enhancement in the symmetry of the molecule from D2h symmetry to D4h, due to the presence of central Zn metal ion. The ZnTPP thin film is exhibiting reverse saturation absorption (RSA) and strong self-defocusing effect. The effective two photon nonlinear absorption coefficients (βeff) and nonlinear refractive index (n2) obtained at different input on-axis peak intensities (I0) are of the order of 10−6 to 10−5 m/W and 10−13 to 10−11 m2/W. The decrease in βeff with the increase in intensity indicates that the observed RSA is due to the excited state absorption (ESA) from T1 triplet state t...
P.C. Rajesh Kumar, K. Janardhana, K.M. Balakrishna, and T. Sheela
Elsevier BV
P.C. Rajesh Kumar, K. Janardhana, and Vincent Crasta
Elsevier BV
K. Janardhana, V. Ravindrachary, P.C. Rajesh Kumar, and Ismayil
Wiley
A 2-pyrazoline,3-(phenyl)-5-(4-N,N-dimethylaminophenyl)-
1H-2-pyrazoline (PDAP) was synthesized and characterized
by Fourier transform infrared, nuclear magnetic
resonance, ultraviolet (UV)–visible, and Z-scan techniques.
The PDAP-doped polyvinyl alcohol composite films
were prepared by solvent casting method using dimethylformamide as solvent. The optical properties of the
composites were studied using UV–visible, steady state
fluorescence, single beam Z-scan technique and degenerate
four wave mixing (DFWM) technique. The optical
constants such as band gap and optical activation
energy were evaluated. The steady state fluorescence
data showed both emission peak wavelengths and intensity
change with PDAP-doping level in the composites.
The open aperture Z-scan of the composite films displayed
reverse saturable absorption. A self-focusing
effect was observed under closed aperture configuration
and the nonlinear refractive index of the film was
observed increasing with the increase of doping. The
third-order nonlinear susceptibility was compared with
that obtained with picoseconds pulses through DFWM
technique. The thermogravimetry analysis shows that
the composites are thermally stable up to 2608C. POLYM.
ENG. SCI., 53:1958–1967, 2013. a2013 Society of Plastics
Engineers
K. Janardhana, V. Ravindrachary, P.C. Rajesh Kumar, Yogisha, and Ismayil
Elsevier BV
K. Janardhana, V. Ravindrachary, P.C. Rajesh Kumar, G. Umesh, K. B. Manjunatha, and Ismayil
AIP
A novel pyrazoline, 3-(phenyl)-5-(4-hydroxyphenyl)-1-(2, 4-dinitrophenyl)-2-pyrazoline (PHDP) was synthesized using standard method and its chemical structure was confirmed using FTIR studies. The linear and non linear optical properties of the compound were studied using UV-Vis and Z-scan techniques. UV-Vis spectrum shows that the compound is transparent in the visible region and absorption in the UV region. The z-scan study shows that the compound possesses third and higher order optical nonlinearity. The calculated optical absorption cross sections indicate that the operating nonlinear mechanism is reverse saturable absorption type. The real part of the third-order nonlinear optical susceptibility χ3 was estimated and the closed aperture data shows that PHDP possess negative nonlinearity.
P.C. Rajesh Kumar, V. Ravindrachary, K. Janardhana, and Boja Poojary
Elsevier BV
P.C. Rajesh Kumar, V. Ravindrachary, K. Janardhana, H.R. Manjunath, Prakash Karegouda, Vincent Crasta, and M.A. Sridhar
Elsevier BV
P. C. Rajesh Kumar, V. Ravindrachary, K Janardhana, H. R. Manjunath, Prakash Karegoudar, Alka B. Garg, R. Mittal, and R. Mukhopadhyay
AIP
Organic compound 1‐(2 thiophene)‐3‐(2, 3, 5‐trichloroph enyl)‐2‐propen‐1‐one [TTCP] with molecular formula C13H7Cl3OS was synthesized using condensation reaction method. FT‐IR spectra were recorded to identify the various functional groups present in the compound. The third harmonic optical nonlinearity test was carried out using z‐scan technique. The single crystals were grown using slow evaporation solution growth technique. Optical absorption studies reveal that the crystal is transparent in the entire visible region and absorption (around 364 nm) takes place in the UV‐region. The single‐crystal XRD studies were carried out, and it was found that the compound crystallizes in the monoclinic system with a space group P21/c. The observed lattice parameters are a = 16.6170(6) A b = 7.6180(5) A c = 10.9280(11) A and V = 1338.47(17) A3.
Vincent Crasta, V. Ravindrachary, P. C. Rajesh Kumar, S. Ganesh, Alka B. Garg, R. Mittal, and R. Mukhopadhyay
AIP
Single crystals of 1‐(4‐methylphenyl)‐3‐(4,N,N‐dimethylamino phenyl)‐2‐propen‐1‐one were irradiated with 72 MeV swift heavy ions of C‐12 with different fluencies 5×1011, 1×1012 and electrons with energy 8 MeV for a dose of 2.25 kGy. The changes in the dielectric properties of these crystals have been studied. The study shows that the dielectric constant increases first and then decreases with the increase of fluence. This variation has been discussed and possible explanations are given. The variation of dielectric loss and the ac conductivity indicates that there is some structural modification within the crystal due to irradiation. The electron irradiation induced ionic polarizibility within the crystal along the electron path, which is reflected in increase in dielectric constant and hence the conductivity.
K. Janardhana, V. Ravindrachary, P. C. Rajesh Kumar, Yogisha, Bhoja Poojary, K. B. Manjunatha, and Ismayil
American Institute of Physics
A new pyrazoline derivative 3‐phenyl‐5‐(4‐N,N‐dimethylaminophenyl)‐1H‐2‐pyrazoline (PDHP) was synthesized using standard method. The structure of the compound was established based on 1H NMR spectrum. The third‐order optical nonlinear properties of PDHP compound were measured using nanosecond Z‐scan method The measured nonlinear absorption coefficient β is 0.27×10−10 m W−1. The magnitude of third order susceptibility is Reχ(3) = =19.94×10−13 esu and Imχx(3) = 5.85×10−13 esu. These experimental results reveal that the PDHP may be a good candidate for optical limiting applications due to its reverse saturated absorption phenomenon
H.R. Manjunath, P.C. Rajesh Kumar, S. Naveen, V. Ravindrachary, M.A. Sridhar, J. Shashidhara Prasad, and Prakash Karegoudar
Elsevier BV