Browsing by Subject "Laser tuning"
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Item Open Access Doppler effect on nanopatterning with nonlinear laser lithography(OSA, 2017) Yavuz, Özgün; Kara, Semih; Tokel, Onur; Pavlov, Ihor; İlday, Fatih ÖmerSummary form only given. Just five years after invention of the laser, laser induced periodic structures (LIPSS) had been reported. However, the structure period is not very uniform in LIPSS. Recently, with nonlinear laser lithography (NLL), long range ordered periodic surface structures had been maintained by exploiting various feedback mechanisms and nonlinearities. Albeit, fine tuning of structure period remains challenging. Here, we present an analogy between Doppler effect and structure period of the NLL which adds a capability of changing the structure period.Item Open Access Femtosecond optical parametric oscillator based on periodically poled KTiOPO4(1998-01-01) Kartaloğlu, T.; Köprülü, K. G.; Aytür, O.; Sundheimer, M.; Risk, W. P.We report a femtosecond optical parametric oscillator based on a periodically poled KTiOPO4 crystal for which quasi-phase matching is achieved with a 24-μm poling period. The singly resonant parametric oscillator, synchronously pumped by a Ti:sapphire laser at a wavelength of 758 nm, generates a signal at 1200 nm and an idler at 2060 nm. The maximum signal power conversion efficiency of the device is 22% with a pump depletion of 69%. We tune the signal wavelength over a 200-nm band by changing the cavity length. In addition, pump wavelength tuning provides output tunability in the 1000-1235-nm range.Item Open Access Phase-matched self-doubling optical parametric oscillator(Optical Society of America, 1997-03-01) Kartaloğlu, T.; Köprülü, K. G.; Aytür, O.We report a synchronously pumped intracavity frequency-doubled optical parametric oscillator that employs a single KTiOPO4 crystal for both parametric generation and frequency doubling. Both nonlinear processes are phase matched for the same direction of propagation in the crystal. The parametric oscillator, pumped by a femtosecond Ti:sapphire laser at a wavelength of 745 nm, generates a green output beam at 540 nm with a 29% power conversion efficiency. Angle tuning in conjunction with pump wavelength tuning provides output tunability in the 530-585-nm range.Item Open Access Single-crystal sum-frequency-generating optical parametric oscillator(Optical Society of America, 1999-09) Köprülü, K. G.; Kartaloğlu, T.; Dikmelik, Y.; Aytür, O.We report a synchronously pumped optical parametric oscillator that generates the sum frequency of the pump and the signal wavelengths. A single KTiOPO4 (KTP) crystal is used for both parametric generation and sum-frequency generation in which these two processes are simultaneously phase matched for the same direction of propagation. The parametric oscillator, pumped by a femtosecond Ti:sapphire laser at a wavelength of 827 nm, generates a blue output beam at 487 nm with 43% power-conversion efficiency. The polarization geometry of simultaneous phase matching requires rotation of the pump polarization before the cavity. Adjusting the group delay between the two orthogonally polarized pump components to compensate for the group-velocity mismatch in the KTP crystal increases the photon-conversion efficiency more than threefold. Angle tuning in conjunction with pump wavelength tuning provides output tunability in the 484–512-nm range. A plane-wave model that takes group-velocity mismatch into account is in good agreement with our experimental results.