Browsing by Subject "Optical frequency conversion"
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Item Open Access Advances in femtosecond single-crystal sum-frequency generating optical parametric oscillators(IEEE, 1998) Köprülü, Kahraman G.; Kartaloğlu, Tolga; Dikmelik, Yamaç; Aytür, OrhanThe effect of compensating the group velocity mismatch between the orthogonal pump components on the conversion efficiency of the optical parametric oscillators (OPOs) was investigated. A femtosecond single-crystal sum-frequency generating optical parametric oscillators (OPO) based on a Ti:sapphire laser pumped KTiOPO4 crystal was used. presented. The crystal was phase matched for a specific signal wavelength corresponding to the operational wavelength of the laser. The crystal was also phase-matched for the sum-frequency generations (SFG) of the pump and the signal beams yielded a blue output beam. The conversion efficiency of the OPOs increased by compensating the group velocity mismatch.Item Open Access Femtosecond self-doubling optical parametric oscillator based on KTiOAsO4(IEEE, 2003) Kartaloğlu, T.; Aytür, O.We report a femtosecond intracavity-frequency-doubled optical parametric oscillator that employs a single KTiOAsO4 crystal for both parametric generation and frequency doubling. This device generates a yellow output beam at 575 nm with 39.4% power conversion efficiency when synchronously pumped by a femtosecond Ti:sapphire laser at a wavelength of 796 nm. An intracavity retarder is employed to alleviate temporal pulse overlap problems associated with group velocity mismatch inside the KTiOAsO4 crystal.Item Open Access Idler-efficiency-enhanced long-wave infrared beam generation using aperiodic orientation-patterned GaAs gratings(Optical Society of America, 2016) Figen, Z. G.; Aytür, O.; Arıkan, OrhanIn this paper, we design aperiodic gratings based on orientation-patterned gallium arsenide (OP-GaAs) for converting 2.1 μm pump laser radiation into long-wave infrared (8-12 μm) in an idler-efficiency-enhanced scheme. These single OP-GaAs gratings placed in an optical parametric oscillator (OPO) or an optical parametric generator (OPG) can simultaneously phase match two optical parametric amplification (OPA) processes, OPA 1 and OPA 2. We use two design methods that allow simultaneous phase matching of two arbitrary χ 2 processes and also free adjustment of their relative strength. The first aperiodic grating design method (Method 1) relies on generating a grating structure that has domain walls located at the zeros of the summation of two cosine functions, each of which has a spatial frequency that equals one of the phase-mismatch terms of the two processes. Some of the domain walls are discarded considering the minimum domain length that is achievable in the production process. In this paper, we propose a second design method (Method 2) that relies on discretizing the crystal length with sample lengths that are much smaller than the minimum domain length and testing each sample's contribution in such a way that the sign of the nonlinearity maximizes the magnitude sum of the real and imaginary parts of the Fourier transform of the grating function at the relevant phase mismatches. Method 2 produces a similar performance as Method 1 in terms of the maximization of the height of either Fourier peak located at the relevant phase mismatch while allowing an adjustable relative height for the two peaks. To our knowledge, this is the first time that aperiodic OP-GaAs gratings have been proposed for efficient long-wave infrared beam generation based on simultaneous phase matching.Item Open Access Multimode pumping of optical parametric oscillators(Institute of Electrical and Electronics Engineers, 1996-02) Marshall, L. R.; Kaz, A.; Aytur, O.Calculations suggest that optical parametric oscillators (OPO's) can be efficiently pumped using multimode, divergent pump sources. The influence of pump beam divergence and mode structure upon OPO performance is measured for both noncritical phase-matching, and OPO's with walkoff. Multimode OPO pumping is shown to be efficient, provided appropriate nonlinear crystals and OPO cavities are employed; the nonlinear crystal must have sufficient angular acceptance to tolerate a divergent pump; the OPO cavity must support modes that match the divergence and spatial intensity characteristics of the pump, For low-order pump modes, the OPO can be made to match the mode of the pump. Higher order pump modes reduce the OPO efficiency, and cause a saturation of efficiency with increasing pump power. The efficiency is degraded in a similar fashion in the presence of walkoff. Multimode pumping is more difficult in longer OPO cavities due to increased buildup time of higher order OPO modes.Item Open Access Performance analysis of an optical packet switch employing full/limited range share per node wavelength conversion(IEEE, 2007) Akar, Nail; Karasan, Ezhan; Muretto, G.; Raffaelli, C.In this paper, we study an asynchronous optical packet switching node equipped with a number of limited range or full range wavelength converters shared per node. The packet traffic is realistically modeled by a superposition of a finite number of on-off sources as opposed to the traditional Poisson model which ignores the limited number of ports on a switch. We both study circular and non-circular limited range wavelength conversion schemes. In our simulations, we employ the far conversion policy where the optical packet is switched onto the farthest available wavelength in the tuning range, which is known to outperform the random conversion policy. We propose an approximate analytical method based on block tridiagonal Markov chains and fixed point iterations to solve for the blocking probabilities in share per node wavelength conversion systems. The method provides an accurate approximation for full range systems and acceptable results for limited range systems.Item Open Access Performance of WDM transport networks(Institute of Electrical and Electronics Engineers, 1998-08) Karasan, E.; Ayanoglu, E.Wavelength division multiplexed point-to-point transport is becoming commonplace in wide area networks. With the expectation that the next step is end-to-end networking of wavelengths (in the optical domain without conversion to electronics), there is a need for new design techniques, a new understanding of the performance issues, and a new performance evaluation methodology in such networks. This paper describes approaches to that end, summarizes research results, and points to open problems.Item Open Access Plane-wave dynamics of optical parametric oscillation with simultaneous sum-frequency generation(Institute of Electrical and Electronics Engineers, 1999-06) Dikmelik, Y.; Akgün, G.; Aytür, O.This paper presents a theoretical analysis of sum-frequency generating optical parametric oscillators where a single nonlinear crystal is used for both parametric generation and sum-frequency generation. In these devices, the parametric and sum-frequency generation processes are both phase matched for the same direction of propagation inside the crystal. Different polarization geometries for which this simultaneous phase-matching condition can potentially be satisfied are identified and categorized, for both birefringent and quasi-phase-matching methods. Plane-wave coupled-mode equations are presented for each of these categories. Solutions of these coupled mode equations and calculation of the single-pass saturated signal gain are outlined. Intracavity signal photon flux density calculations based on these solutions lead to stable steady-state upconversion, multistability, and chaos. The dependence of the photon conversion efficiency on various design parameters are investigated.Item Open Access Plane-wave dynamics of optical parametric oscillation with simultaneous sum-frequency generation(IEEE, 1998) Akgün, Gülbin; Dikmelik, Yamaç; Aytür, OrhanThe plane wave dynamics of a single-crystal upconversion optical parametric oscillators (OPO) with simultaneous sum-frequency generation (SFG) was studied. It was presumed that simultaneous phase-matching of the SFG and OPO processes were achieved by utilizing birefringent phase matching (BPM). Potential polarization geometries for collinear BPM led to four different sets of coupled mode equations depending on which field components were common to the two processes. The sets were designated as classes A through D. Classes A and D were efficient frequency upconverters. The performance of class A OPO's was limited by crystal properties whereas classes C and D was optimized by adjusting the polarization rotation angle.Item Open Access Plane-wave theory of self-doubling optical parametric oscillators(Institute of Electrical and Electronics Engineers, 1998-03) Aytür, O.; Dikmelik, Y.This paper presents a theoretical analysis of self-doubling optical parametric oscillators (OPO's) where a single nonlinear crystal is used for both parametric generation and frequency doubling. In these devices, the parametric generation and frequency-doubling processes are both phase matched for the same direction of propagation inside the crystal. Different polarization geometries for which this simultaneous phase-matching condition can potentially be satisfied are identified and categorized. Plane-wave coupled-mode equations are presented for each of these categories. Numerical solutions of these coupled-mode equations and calculation of the single-pass saturated signal gain are outlined. Intracavity signal photon flux calculations iased on these numerical solutions are presented. The dependence of performance measures such as the photon conversion efficiency on various design parameters are investigated.Item Open Access Scalable wavelength-converting crossbar switches(IEEE, 2004-10) Demir, Hilmi Volkan; Sabnis, V. A.; Zheng, J. F.; Fidaner, O.; Harris, J. S.; Miller, D. A. B.We report scalable low-power wavelength-converting Crossbar switches that monolithically integrate two-dimensional compact arrays of surface-normal photodiodes with quantum-well waveguide modulators. We demonstrate proof-of-concept, electrically reconfigurable 2 x 2 crossbars that perform unconstrained wavelength conversion across 35 nm in the C-band (1530-1565 nm), using only <4.3-mW absorbed input optical power, and with 10-dB extinction ratio at 1.25 Gb/s. Such wavelength-converting crossbars provide complete flexibility to selectively convert any of the input wavelengths to any of the output wavelengths at high data bit rates in telecommunication, with the input and output wavelengths being arbitrarily chosen within the C-band.Item Open Access Single-crystal sum-frequency generating optical parametric oscillator(IEEE, 1997) Köprülü, Kahraman G.; Kartaloğlu, Tolga; Aytür, OrhanA sum-frequency generating optical parametric oscillator (OPO), where a single crystal is employed for both parametric oscillation and sum frequency generation, is presented. The OPO is based on a KTiOPO4 crystal that is pumped by a Ti:sapphire laser operating at a wavelength of 828 nm. The two-step conversion is efficient, since both nonlinear conversion processes are phase matched in the same crystal.