Browsing by Subject "Grating compressors"
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Item Open Access Doping management for high-power fiber lasers: 100 W, few-picosecond pulse generation from an all-fiber-integrated amplifier(Optical Society of America, 2012-07-16) Elahi, P.; Yilmaz, S.; Akçaalan, Ö.; Kalaycioğlu, H.; Öktem, B.; Şenel, Ç.; Ilday, F. Ö.; Eken, K.Thermal effects, which limit the average power, can be minimized by using low-doped, longer gain fibers, whereas the presence of nonlinear effects requires use of high-doped, shorter fibers to maximize the peak power. We propose the use of varying doping levels along the gain fiber to circumvent these opposing requirements. By analogy to dispersion management and nonlinearity management, we refer to this scheme as doping management. As a practical first implementation, we report on the development of a fiber laser-amplifier system, the last stage of which has a hybrid gain fiber composed of high-doped and low-doped Yb fibers. The amplifier generates 100 W at 100 MHz with pulse energy of 1 μJ. The seed source is a passively mode-locked fiber oscillator operating in the all-normaldispersion regime. The amplifier comprises three stages, which are all-fiber-integrated, delivering 13 ps pulses at full power. By optionally placing a grating compressor after the first stage amplifier, chirp of the seed pulses can be controlled, which allows an extra degree of freedom in the interplay between dispersion and self-phase modulation. This way, the laser delivers 4.5 ps pulses with ∼200 kW peak power directly from fiber, without using external pulse compression.Item Open Access Fiber laser-microscope system for femtosecond photodisruption of biological samples(Optical Society of America, 2012-02-22) Yavaş, Seydi; Erdoğan, Mutlu; Gürel, Kutan; İlday, F. Ömer; Eldeniz, Y. B.; Tazebay, Uygar H.We report on the development of a ultrafast fiber lasermicroscope system for femtosecond photodisruption of biological targets. A mode-locked Yb-fiber laser oscillator generates few-nJ pulses at 32.7 MHz repetition rate, amplified up to ~125 nJ at 1030 nm. Following dechirping in a grating compressor, ~240 fs-long pulses are delivered to the sample through a diffraction-limited microscope, which allows real-time imaging and control. The laser can generate arbitrary pulse patterns, formed by two acousto-optic modulators (AOM) controlled by a custom-developed fieldprogrammable gate array (FPGA) controller. This capability opens the route to fine optimization of the ablation processes and management of thermal effects. Sample position, exposure time and imaging are all computerized. The capability of the system to perform femtosecond photodisruption is demonstrated through experiments on tissue and individual cells.