Graduate Seminar in Optics-May 16, 2018 Wednesday

Author: Graduate School of Sciences and Engineering
Time: 17:30
Location: ENG 208




Speaker            : Işınsu Baylam, PhD 

Title                  : Voltage-controlled graphene-based saturable absorbers

Date                  : May 16, 2018 Wednesday

Time                 : 17.30
Cookie & Tea  : 17.30
Place                     ENG 208

Abstract: Graphene, a gapless two-dimensional (2D) nanomaterial, has emerged as an alternative saturable absorber to other semiconductors due to its nearly constant broadband absorption of 2.3%. It has been shown that graphene and graphene-based nanomaterials can be used as efficient saturable absorbers to generate ultrashort pulses from lasers operating in the near- and mid-infrared. However, the 2.3% absorption of the monolayer graphene introduces operational challenges to the lasers with low gains. To obviate such challenges, the Fermi level position of the graphene can be varied to control the amount of absorption at the desired wavelength. For this purpose, chemically- or electrostatically-doped novel graphene architectures with reduced optical insertion losses can be used to optimize the power performance of the femtosecond lasers.

In this talk, the use of carbon-based saturable absorbers to generate ultrashort pulses from solid-state lasers will be presented and their current drawbacks will be discussed. This will be followed by the overview of the possible approaches, which have been demonstrated to shift the Fermi level of graphene to control the amount of absorption at the desired wavelength. At this point, the voltage-controlled graphene-based supercapacitor architectures proposed by our groups will be demonstrated and the femtosecond pulse generation results obtained with these devices will be discussed.

In the remainder part of the talk, the infrastructure of Ultrafast Laser Laboratory located at Koç University Surface Science and Technology Center (KUYTAM) will be introduced to the audience to enable possible collaborations.

Bio: Dr. Işınsu Baylam received her BS degree in Physics from Bilkent University in 2010, MS, and PhD degrees in Physics from Koç University in 2012 and 2017. During her MS and PhD studies, she focused on graphene-based nanomaterials and their use as saturable absorbers to generate ultrashort pulses from solid-state lasers. She currently continues her studies in Ultrafast Laser Laboratory (KUYTAM) as a doctoral researcher. Her research interests include graphene-based saturable absorbers, near- and mid-infrared solid-state lasers, ultrafast laser spectroscopy, and nonlinear optics.