Graphene mode-locked lasers
Graphene, the latest discovered allotrope of carbon, attracts the attention of scientists all over the world. Thanks to its unique optical properties, graphene is considered as a future material for optoelectronics and laser technology. The Laser & Fiber Electronics Group, as the only one in Poland, is successfully working on the application of graphene in lasers which emit ultrashort pulses of light.
Our research focuses on the usage of graphene as so called saturable absorbers in fiber lasers operating in the infrared spectral region. Thanks to the broadband and wavelength independent absorption of light, its ultrashort recovery time and third order nonlinear susceptibility, graphene might be used as a new kind of saturable absorber for mode-locking of fiber and bulk lasers. As a result, optical pulses as short as hundreds of femtoseconds (10-15 s) can be generated. Such lasers are on demand of many applications, including telecommunications, medicine (surgery, dermatology), materials processing, precise metrology, microscopy and spectroscopy.
The first graphene mode-locked fiber laser in Poland was developed by Jaroslaw Sotor and Grzegorz Sobon from LFEG in November 2011. Since then, the Group achieved many outstanding results, often unique in the world, like: the first polarization-maintaining femtosecond fiber laser utilizing graphene [1,2]; a graphene mode-locked laser with highest repetition frequency (2.22 GHz) ; thulium-doped fiber laser operating in the mid-infrared (around 2 μm) ; lasers with graphene oxide and reduced graphene oxide ; lasers based on CVD-graphene  or the first chirped pulse amplification (CPA) setup utilizing a graphene-based laser  and many others.
Currently, the Group is carrying out two research projects devoted to graphene. The first one, financed by the Polish National Science Centre, focuses on nonlinear optical properties of graphene and its usage as saturable absorber in fiber lasers operating at wavelengths ranging from 1 µm to 2 µm. The second project, financed by the National Centre for Research and Development is carried out in collaboration with the Institute of Electronic Materials Technology (Warsaw), one of the world’s leading manufacturer of high-quality graphene. The goal of the project is to develop prototypes of graphene-based ultrafast fiber lasers operating in the IR spectral region (1560 nm), which will be commercialized by an industrial partner.
Most important journal articles on graphene mode-locked fiber lasers published by the Group:
- “Scalar soliton generation in all-polarization maintaining, graphene mode-locked fiber laser“, Optics Letters 37, 2166-2168 (2012)
- “All-polarization maintaining femtosecond Er-doped fiber laser mode-locked by graphene saturable absorber”, Laser Physics Letters 9, 581–586 (2012)
- “Passive harmonic mode-locking in Er-doped fiber laser based on graphene saturable absorber with repetition rates scalable to 2.22 GHz”, Applied Physics Letters 100, 161109 (2012)
- “Thulium-doped all-fiber laser mode-locked by CVD-graphene/PMMA saturable absorber“, Optics Express 21, 12797-12802 (2013)
- “Graphene Oxide vs. Reduced Graphene Oxide as saturable absorbers for Er-doped passively mode-locked fiber laser”, Optics Express 20, 19463-19473 (2012)
- „Er-doped Fiber Laser Mode-locked by CVD-graphene Saturable Absorber”, Journal of Lightwave Technology 30, 2770-2775 (2012)
- “Chirped pulse amplification of a femtosecond Er-doped fiber laser mode-locked by a graphene saturable absorber“, Laser Physics Letters 10, 035104 (2013)