Nano-structured carbon saturable absorbers (single-walled carbon nanotubes, graphene, and graphene-based super capacitors) can be employed as fast modulators to initiate femtosecond pulse generation from lasers. The presentation will describe some of our recent experiments where such devices were employed to generate femtosecond pulses from different tunable solid-state lasers operating in the near to mid-infrared between 1250 and 2500 nm. Our experiments show that voltage controlled graphene-based super capacitor structures can be employed as saturable absorbers with adjustable loss and offer a versatile approach to pulse generation over a wide wavelength range. Data showing the nonlinear optical characteristics of the modulators as well as the mode-locked performance of the femtosecond lasers will be presented. 

Biography:
Alphan Sennaroğlu is the Dean of the College of Sciences and the Director of the Surface Science and Technology Center (KUYTAM) at Koç University.  He is also a professor in the Departments of Physics and Electrical-Electronics Engineering. He received his BS, MS, and PhD degrees in Electrical Engineering from Cornell University in 1988, 1990, and 1994, respectively. He founded the Koç University Laser Research Laboratory in 1994 and has led its research activities in the areas of infrared solid-state lasers, ultrafast lasers, and spectroscopy. He was a visiting researcher at the Massachusetts Institute of Technology during the 2002-2003 and 2009-2010 academic years, and in the summers of 2005-2008. He served as a Program Chair of the Advanced Solid-State Photonics Meeting and Advanced Solid-State Lasers Congress (both organized by the Optical Society of America) between 2010 and 2016.  In 2012, he also served as the General Chair of the Advanced Solid-State Photonics Meeting. In 2004 and 2006, he was the Program Chair of the Solid-State Lasers and Amplifiers Conference during the Photonics Europe meeting in Strasbourg, France.  He has also served as a member of the Technical Program Committee for various conferences including CLEO, CLEO-Europe, Photonics Europe, Advanced Solid-State Photonics, and Europhoton. Alphan Sennaroğlu is the recipient of the 2013 TÜBİTAK Science Award. He is a Fellow of the Optical Society of America and a Senior Member of IEEE (Institute of Electrical and Electronics Engineers).  He authored the book Photonics and Laser Engineering: Principles, Devices and Applications which was published by McGraw-Hill in 2010.

Contact: iikaya@sabanciuniv.edu