Person: AKŞİMŞEK, HÜSEYİN SİNAN
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Dr. Öğr. Üyesi
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AKŞİMŞEK
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HÜSEYİN SİNAN
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Publication Embargo New approach for thickness determination of solution-deposited graphene thin films(Amer Chemical Soc, 1155 16th St, Nw, Washington, Dc 20036 USA, 2017-06) Jussila, Henri; Albrow Owen, Tom; Yang, He; Hu, Guohua; Granqvist, Niko; Lipsanen, Harri; Howe, Richard C. T.; Sun, Zhipei; Hasan, Tawfique; AKŞİMŞEK, HÜSEYİN SİNAN; 107154Solution processing-based fabrication techniques such as liquid phase exfoliation may enable economically feasible utilization of graphene and related nanomaterials in real-world devices in the near future. However, measurement of the thickness of the thin film structures fabricated by these approaches remains a significant challenge. By using surface plasmon resonance (SPR), a simple, accurate, and quick measurement of the deposited thickness for inkjet-printed graphene thin films is reported here. We show that the SPR technique is convenient and well-suited for the measurement of thin films formulated from nanomaterial inks, even at sub-10 nm thickness. We also demonstrate that the analysis required to obtain results from the SPR measurements is significantly reduced compared to that required for atomic force microscopy (AFM) or stylus profilometer, and much less open to interpretation. The gathered data implies that the film thickness increases linearly with increasing number of printing repetitions. In addition, SPR also reveals the complex refractive index of the printed thin films composed of exfoliated graphene flakes, providing a more rigorous explanation of the optical absorption than that provided by a combination of AFM/profilometer and the extinction coefficient of mechanically exfoliated graphene flakes. Our results suggest that the SPR method may provide a new pathway for the thickness measurement of thin films fabricated from any nanomaterial containing inks.Publication Metadata only Graphene actively Q-switched lasers(2017-05-05) Li, Diao; Xue, Hui; Qi, Mei; Wang, Yadong; Chekurov, Nikolai; Kim, Wonjae; Li, Changfeng; Riikonen, Juha; Ye, Fangwei; Dai, Qing; Ren, Zhaoyu; Bai, Jintao; Hasan, Tawfique; Lipsanen, Harri; Sun, Zhipei; AKŞİMŞEK, HÜSEYİN SİNAN; 107154Graphene electro-optic modulators (GEOMs) are emerging as a viable alternative to conventional material-based modulators mainly due to their broadband and ultrafast performance. These GEOMs with combined advantages of small footprint and low energy consumption can potentially enable various high-performance applications that are not possible using conventional approaches. Here, we report the first actively Q-switched lasers with a GEOM. In contrast to the previously reported lasers that are passively modulated by two-dimensional layered material-based saturable absorbers, our actively modulated laser concept represents significant advantages, such as electrically tunable output parameters (e.g. output repetition rate, pulse duration and pulse energy) and electro-optical synchronization. Using a single GEOM, we generate broadband Q-switched pulses at ~1.55 and 2 μm with output energies of up to 123 nJ. This indicates the broadband pulse generation capability of the graphene-based active devices, superior to widely used bulk material-based active modulation approaches. Our results demonstrate a simple and viable design towards broadband, high-repetition-rate, electrically modulated ultrafast lasers for various applications, such as telecommunications and spectroscopy.