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Your search keyword '"Karafolas, N."' showing total 39 results
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39 results on '"Karafolas, N."'

2. Long distance measurement with a femtosecond laser based frequency comb

Author

Bhattacharya, N., Cui, M., Zeitouny, M., Urbach, Paul, van den Berg, S., Armandillo, E., Cugny, B., and Karafolas, N.

Subjects
Physics, business.industry, Carrier-envelope phase, Physics::Optics, Frequency standard, Laser, Atomic clock, law.invention, Metrology, Frequency comb, Optics, law, Femtosecond, Pulse wave, Physics::Atomic Physics, business
Abstract

Recent advances in the field of ultra-short pulse lasers have led to the development of reliable sources of carrier envelope phase stabilized femtosecond pulses. The pulse train generated by such a source has a frequency spectrum that consists of discrete, regularly spaced lines known as a frequency comb. In this case both the frequency repetition and the carrier-envelope-offset frequency are referenced to a frequency standard, like an atomic clock. As a result the accuracy of the frequency standard is transferred to the optical domain, with the frequency comb as transfer oscillator. These unique properties allow the frequency comb to be applied as a versatile tool, not only for time and frequency metrology, but also in fundamental physics, high-precision spectroscopy, and laser noise characterization. The pulse-to-pulse phase relationship of the light emitted by the frequency comb has opened up new directions for long range highly accurate distance measurement.

Published
2018

3. Development and optical performance tests of the Si immersed grating demonstrator for E-ELT METIS

Author

Navarro, R., Agócs, T., Venema, L., Amerongen, A.H., Rodenhuis, M., Hoogeveen, R.W.M., Coppens, T., Brandl, B.R., Vink, R., Cugny, B., Karafolas, N., and Sodnik, Z.

Subjects
Materials science, Fabrication, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Physics::Optics, 02 engineering and technology, Grating, 01 natural sciences, 010309 optics, Semiconductor industry, Interferometry, 020210 optoelectronics & photonics, Optics, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Metis, Wafer, Physics::Atomic Physics, business, Spectrograph, Throughput (business)
Abstract

Immersed gratings offer several advantages over conventional gratings: more compact spectrograph designs, and by using standard semiconductor industry techniques, higher diffraction-efficiency and lower stray-light can be achieved. We present the optical tests of the silicon immersed grating demonstrator for the Mid-infrared E-ELT Imager and Spectrograph, METIS. We detail the interferometric tests that were done to measure the wavefront-error and present the results of the throughput and stray-light measurements. We also elaborate on the challenges encountered and lessons learned during the immersed grating demonstrator test campaign that helped us to improve the fabrication processes of the grating patterning on the wafer.

Published
2017

28. Optical digital communications in telecom payloads

Author

Veli Heikkinen, Eveliina Juntunen, Mikko Karppinen, Kari Kautio, Jyrki Ollila, Aila Sitomaniemi, Antti Tanskanen, Rory Casey, Shane Scott, Gachon, H., Sotom, M., Venet, N., Jaakko Toivonen, Tuominen, T., and Karafolas, N.

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