Dr. Harendra N. J. Fernando Profile

Dr. Harendra N. J. Fernando

Research Scientist at Leibniz-Institut für Astrophysik Potsdam

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Publications (11)

Proceedings Article | 28 July 2014 Paper

Interferometers and spectrographs on silicon-platform for astrophysics: trends of astrophotonics

Harendra N. Fernando, Andreas Stoll, Nick Cvetojevic, René Eisemann, Nuwan Tharanga, Christopher Holmes, Michael Böhm, Martin Roth, Roger Haynes, Lars Zimmermann

Proceedings Volume 9151, 915148 (2014) https://doi.org/10.1117/12.2056500

KEYWORDS: Waveguides, Silicon, Birefringence, Interferometers, Spectrographs, Astronomy, Computer aided design, Spectral resolution, Photonics, Integrated photonics

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Proceedings Article | 13 September 2012 Paper

Planar integrated photonics spectrograph on silicon-nitride-on-insulator: densely integrated systems for astrophotonics and spectroscopy

Harendra N. Fernando, Andreas Stoll, René Eisermann, Jose Boggio, Lars Zimmermann, Roger Haynes, Martin Roth

Proceedings Volume 8450, 845046 (2012) https://doi.org/10.1117/12.925561

KEYWORDS: Waveguides, Silicon, Receivers, Integrated photonics, Computer aided design, Spectrographs, Spectroscopes, Spectral resolution, Astrophotonics, Beam propagation method

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Proceedings Article | 13 September 2012 Paper

Astronomical optical frequency comb generation in nonlinear fibres and ring resonators: optimization studies

J. Chavez Boggio, T. Fremberg, D. Bodenmüller, M. Wysmolek, H. Sanyic, H. Fernando, J. Neumann, D. Kracht, R. Haynes, M. Roth

Proceedings Volume 8450, 84501H (2012) https://doi.org/10.1117/12.925535

KEYWORDS: Dispersion, Frequency combs, Silicon, Waveguides, Astronomy, Calibration, Refractive index, Spectrographs, Cladding, Astronomical imaging

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We here discuss recent progress on astronomical optical frequency comb generation at innoFSPEC-Potsdam. Two different platforms (and approaches) are numerically and experimentally investigated targeting medium and low resolution spectrographs at astronomical facilities in which innoFSPEC is currently involved. In the first approach, a frequency comb is generated by propagating two lasers through three nonlinear stages – the first two stages serve for the generation of low-noise ultra-short pulses, while the final stage is a low-dispersion highly-nonlinear fibre where the pulses undergo strong spectral broadening. In our approach, the wavelength of one of the lasers can be tuned allowing the comb line spacing being continuously varied during the calibration procedure – this tuning capability is expected to improve the calibration accuracy since the CCD detector response can be fully scanned. The input power, the dispersion, the nonlinear coefficient, and fibre lengths in the nonlinear stages are defined and optimized by solving the Generalized Nonlinear Schrodinger Equation. Experimentally, we generate the 250GHz line-spacing frequency comb using two narrow linewidth lasers that are adiabatically compressed in a standard fibre first and then in a double-clad Er/Yb doped fibre. The spectral broadening finally takes place in a highly nonlinear fibre resulting in an astro-comb with 250 calibration lines (covering a bandwidth of 500 nm) with good spectral equalization. In the second approach, we aim to generate optical frequency combs in dispersion-optimized silicon nitride ring resonators. A technique for lowering and flattening the chromatic dispersion in silicon nitride waveguides with silica cladding is proposed and demonstrated. By minimizing the waveguide dispersion in the resonator two goals are targeted: enhancing the phase matching for non-linear interactions and producing equally spaced resonances. For this purpose, instead of one cladding layer our design incorporates two layers with appropriate thicknesses. We demonstrate a nearly zero dispersion (with +/- 4 ps/nm-km variation) over the spectral region from 1.4 to 2.3 microns. The techniques reported here should open new avenues for the generation of compact astronomical frequency comb sources on a chip or in nonlinear fibres.

Proceedings Article | 10 May 2012 Paper

Arrayed waveguide gratings beyond communication: utilization of entire image-plane of output star-coupler for spectroscopy and sensing

Harendra N. Fernando, Andreas Stoll, Jose Boggio, Roger Haynes, Martin Roth

Proceedings Volume 8431, 84311U (2012) https://doi.org/10.1117/12.923145

KEYWORDS: Waveguides, Receivers, Spectroscopy, Silicon, Imaging spectroscopy, Spectral resolution, Phased array optics, Spectroscopes, Refractive index, Beam propagation method

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Proceedings Article | 5 May 2012 Paper

Precise control of dispersion flatness in silicon nitride waveguides by cladding refractive index engineering

D. Bodenmüller, J. M. Chavez Boggio, H. N. J. Fernando, R. Haynes, M. Roth

Proceedings Volume 8429, 84290V (2012) https://doi.org/10.1117/12.922520

KEYWORDS: Dispersion, Refractive index, Silicon, Waveguides, Cladding, Silica, Integrated photonics, Near infrared, Doping, Slow light

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Proceedings Article | 20 May 2009 Paper

Ratiometric wavelength monitor using a pair of symmetrical multimode interference structures based on silicon-on-insulator (SOI)

Agus Muhamad Hatta, Gerald Farrell, Yuliya Semenova, Harendra Fernando

Proceedings Volume 7366, 73660S (2009) https://doi.org/10.1117/12.821214

KEYWORDS: Brain-machine interfaces, Waveguides, Silicon, Optical filters, Structural design, Spectral resolution, Signal to noise ratio, Photodetectors, Interference (communication), Fiber Bragg gratings

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Proceedings Article | 3 November 2006 Paper

Application of a new time-correlated single photon counting instrument in a fiber-based quantum cryptography system

Iris P. S. Choi, Harendra N. J. Fernando, Paul Townsend, Michael Wahl

Proceedings Volume 6372, 637210 (2006) https://doi.org/10.1117/12.686152

KEYWORDS: Quantum key distribution, Sensors, Coarse wavelength division multiplexing, Phase shifts, Data modeling, Single photon, Quantum cryptography, Raman scattering, Picosecond phenomena, Data acquisition

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Proceedings Article | 20 April 2006 Paper

Optimal design, fabrication, and characterisation of GeO₂-SiO₂ doped silica multimode-interference couplers

H. N. J. Fernando, M. Hayden, P. Hughes

Proceedings Volume 6183, 61830V (2006) https://doi.org/10.1117/12.662860

KEYWORDS: Waveguides, Brain-machine interfaces, Plasma enhanced chemical vapor deposition, Photonic integrated circuits, Silica, Ions, Single mode fibers, Packaging, Etching, Integrated optics

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Proceedings Article | 15 April 2003 Paper

Grating-assisted add-drop multiplexer realized in silica-on-silicon technology

Lech Wosinski, Matteo Dainese, Harendra Fernando, Torsten Augustsson

Proceedings Volume 4941, (2003) https://doi.org/10.1117/12.468509

KEYWORDS: Waveguides, Multiplexers, Fiber Bragg gratings, Polarization, Optical filters, Photonic integrated circuits, Hydrogen, Optical design, Cladding, Plasma enhanced chemical vapor deposition

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Proceedings Article | 15 December 2000 Paper

PECVD technology for low-temperature fabrication of silica-on-silicon-based channel waveguides and devices

Lech Wosinski, Jayanta Sahu, Matteo Dainese, Harendra Fernando

Proceedings Volume 4087, (2000) https://doi.org/10.1117/12.406444

KEYWORDS: Oxides, Silica, Channel waveguides, Plasma enhanced chemical vapor deposition, Waveguides, Silicon, Nitrous oxide, Annealing, Absorption, Optical communications

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Proceedings Article | 29 December 1999 Paper

Reduction of absorption loss in silica-on-silicon channel waveguides fabricated by low-temperature PECVD process

Jayanta Sahu, Lech Wosinski, Harendra Fernando

Proceedings Volume 4016, (1999) https://doi.org/10.1117/12.373601

KEYWORDS: Waveguides, Plasma enhanced chemical vapor deposition, Annealing, Channel waveguides, Absorption, Silica, Fabrication, Silicon, Refractive index, Nitrous oxide

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Showing 5 of 11 publications

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