Optical Sensors: Refractive index sensor (RIS) technologies thrive in recent years, finding ever-expanding applications in chemistry, life sciences, industrial process monitoring, etc. Mach-Zehnder interferometer, micro-ring resonator, optical fiber grating, or surface plasmon resonance concepts, to name just a few, have been proven capable for sensitive detection of refractive index perturbations caused by slight compositional alterations in substances. We evaluate various characteristic properties of Fresnel reflectance upon planar or fiber core/claddin interfaces, with the intension to design novel, multifunctional, alignment-tolerant RISs. Within this line of research, we have previously contributed to demonstrating the use of Fresnel reflectance fiber sensors in real time monitoring of isothermal polymer curing.
Optical Parametric Oscillators: OPOs are laser-like broadly-tunable coherent-radiation sources of particular interest to spectroscopic applications. They exploit gain via parametric amplification instead of stimulated emission: an OPO down-converts a higher-frequency pump beam into two lower-frequency output beams, known as signal and idler, respectively. Pump, signal and idler are bounded by the laws of energy and momentum conservation. Nonlinear conversion – in cw or pulse mode – occurs inside a χ(2) nonlinear medium that is placed within a – singly or doubly – resonant cavity. We investigate novel OPO cavity architectures, with particular emphasis on femtosecond synchronous pumping (SPOPO) designs. This project led to the first demostration of a harrmonic pump geometry that permits repetition-rate increase in SPOPO cavities longer than the fundamental synchronous length. Our discovery may penetrate application areas where high-speed pulse trains are needed, without resorting to miniaturization of optical components.
The prototype was built and operates at partner’s premises [ICFO, Barcelona, Spain].
Group’s journal publications on this topic [click for more]
10 J. Oelhafen, T. Mayr, F. Dorner, K. Moutzouris, J. Roths, K. Drechsler. Fiber optic measurement system for Fresnel reflection sensing: Calibration, uncertainty and exemplary application in temperature-modulated isothermal polymer curing. Journal of Lightwave Technology 36, 939 (2018).
1 Esteban-Martin, O. Kokabee, K. Moutzouris, M. Ebrahim-Zadeh. High-harmonic-repetition-rate, 1 GHz femtosecond optical parametric oscillator pumped by a 76-MHz Ti:sapphire laser. Optics Letters 34, 428, (2009).
Group’s conference publications on this topic [click for more]
7 J. Oelhafen, T. Mayrs, K. Moutzouris, J. Roths, K. Drechsler. Calibration and uncertainty of a fibre optic measurement system for Fresnel reflectometer sensors. 25th International Conference on Optical Fiber Sensors. 24 – 28 April 2017. Libo Yuan Jeju, Republic of Korea.
2 O. Kokabee, A. Esteban-Martin, K. Moutzouris, M. Ebrahim-Zadeh. Extended-cavity GHz-repetition-rate femtosecond optical parametric oscillator pumped at 76 MHz. European Conference on Lasers and Electro-Optics. 14 – 19 June 2009. Munich, Germany.
1 O. Kokabee, A. Esteban Martin, K. Moutzouris, M. Ebrahim-Zadeh. 1-GHz femtosecond optical parametric oscillator pumped by a 76-MHz Ti:sapphire Laser. Conference on Lasers and Electro-Optics (CLEO). 31 May – 5 June 2009. Baltimore, USA.