Browsing by Subject "Optical parametric oscillators"

Now showing 1 - 15 of 15

Open Access
Advances in femtosecond single-crystal sum-frequency generating optical parametric oscillators
(IEEE, 1998) Köprülü, Kahraman G.; Kartaloğlu, Tolga; Dikmelik, Yamaç; Aytür, Orhan
The 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.
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.
Open Access
Highly efficient wavelength conversion of Q-switched Nd: YAG lasers into a red wavelength
(Institute of Electrical and Electronics Engineers, 2006) Figen, Z. G.; Yalabik, A.; Aytür, O.
We report a nanosecond upconversion optical parametric oscillator which can convert the output of a Nd:YAG laser at 1064-nm wavelength into 627 nm with high efficiency. This device is based on a single KTiOAsO4 crystal that is simultaneously phase matched for optical parametric generation and sum-frequency generation. Pumped at a wavelength of 1064 nm by a Q-switched Nd:YAG laser in a double-pass configuration, this device produces 14.2-ns-long 5.8-mJ red pulses at a wavelength of 627 nm with 29% energy conversion efficiency. In addition, we developed a theoretical model for this device, whose predictions agree reasonably well with our experimental results. It is possible to scale this device for use with higher energy pump lasers and to shape it into a physically small semi-monolithic configuration.
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, Orhan
In 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 Ï‡ 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.
Open Access
Laser wavelength upconversion with optical parametric oscillators using simultaneously phase-matched crystals
(2002) Kartaloğlu, Tolga
In this thesis, we present our work on optical parametric oscillators that employ a single nonlinear crystal that is simultaneously-phase-matched for second-harmonic or sum-frequency generation in order to obtain frequency upconversion of laser radiation. We achieved simultaneous phase matching of optical parametric amplification together with second harmonic generation or sum frequency generation in bulk KT10P04 and KTi0 As04 crystals, and in an aperiodically-poled LiNbOs crystal. We demonstrated very efficient frequency conversion of pulsed and continuous-wave lasers to higher frequencies with power conversion efficiencies reaching 40%. In addition, we present our work on an intracavity-doubled optical parametric oscillator that employs a periodicallypoled KT10P 04 crystal for optical parametric amplification and an intracavity (3- Ba2B04 crystal for second harmonic generation. In this thesis, we also introduce a method for designing aperiodic grating structures for simultaneous phase matching in poled nonlinear crystals. In contrast to periodic grating structures, a grating structure designed using our method allows one to achieve simultaneous quasi-phase matching of two arbitrarily chosen nonlinear interactions with freely adjustable coupling coefficients.
Open Access
Nanosecond sum-frequency generating optical parametric oscillator using simultaneous phase matching
(Optical Society of American (OSA), 2005) Figen, Z.G.; Aytür O.
We report a nanosecond sum-frequency generating optical parametric oscillator based on a single KTiOAsO4 crystal that is simultaneously phase matched for optical parametric generation and sum-frequency generation. Pumped at a wavelength of 1064 nm by a Q-switched Nd:YAG laser, this device produces 10.4-ns-long 8.3 mJ red pulses at a wavelength of 627 nm with 21% energy conversion efficiency. This device provides a simple and efficient method for converting high energy Nd:YAG lasers to a red wavelength. © 2005 Optical Society of America.
Open Access
Nanosecond upconversion optical parametric oscillators
(2005) Figen, Ziya Gürkan
In this thesis, we demonstrate a technique for highly efficient red beam generation using nanosecond upconversion optical parametric oscillators based on KTiOAsO4 crystals that are simultaneously phase matched for optical parametric generation and sum-frequency generation. Pumped at a wavelength of 1064 nm by a Qswitched Nd:YAG laser, these devices produce red output beams at 627 nm with 1064-nm-to-627-nm energy conversion efficiencies reaching 20% for the singlepass pumping and 30% for the double-pass pumping. Our devices are simpler in architecture compared to other devices converting nanosecond Nd:YAG laser radiation into red wavelengths. A typical nanosecond upconversion optical parametric oscillator is comprised of three cavity mirrors which are all high reflectors at the signal wavelength (1525 nm), a 2-cm-long KTiOAsO4 crystal, and an intracavity retarder plate for rotating the polarization of the signal beam. The total cavity length is under 5 cm. With its small size, the device can be shaped into a module to be placed in front of Nd:YAG lasers for highly efficient red beam generation. The single-pass sum-frequency generating optical parametric oscillator is the first demonstration of a nanosecond optical parametric oscillator using simultaneous phase matching. We have fully characterized these devices in terms of their energy output as functions of polarization rotation angle and input pump energy, time profiles, spatial beam profiles, and spectra of the output. In this thesis, we also present our work on modelling continuous-wave intracavity optical parametric oscillators.
Open Access
Phase-matched self-doubling optical parametric oscillator
(IEEE, 1996) Kartaloğlu, Tolga; Köprülü, Kahraman G.; Aytür, Orhan
A new self-doubling optical parametric oscillator (OPO) uses a single nonlinear crystal for both parametric generation and frequency doubling. It is based on a KTiOPO4 (KTP) crystal pumped by a Ti:Sapphire laser operating at a wavelength of 739 nm. The crystal is cut such that the signal wavelength of the OPO is at 1064 nm, corresponding to an idler wavelength of 2420 nm. The OPO cavity resonates only the signal wavelength. The signal beam is also phase-matched for second harmonic generation (SHG) at the same crystal orientation. With proper polarization rotation, an output beam at a wavelength of 532 nm can be obtained.
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.
Open Access
Plane-wave dynamics of optical parametric oscillation with simultaneous sum-frequency generation
(IEEE, 1998) Akgün, Gülbin; Dikmelik, Yamaç; Aytür, Orhan
The 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.
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.
Open Access
Plane-wave theory of single-crystal upconversion optical parametric oscillators
(1998) Dikmelik, Yamaç
'rhis thesis pi'('s('nts a theoi'etical analysis of single-crystal upconversion optical parametric oscillators (OPO’s) where a single nonlinear crystal is used for both the OPO and sum-frequency generation (SPG) or second-harmonic generation (SHG). In these devices, the OPO and SFG/SHG 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 biréfringent. a.nd quasi-phcise matching methods. This categorization results in four classes of sumfrequency generating OPO’s (SF-OPO’s) and three classes of self-doubling OPO’s (SD-OPO’s). Plane-wa.ve coupled mode equations a.re presented for each of these seven classes. Solutions of these coupled mode equations, and calculation of the single-pass saturated signal gain are outlined. The dependence of the photon conversion efficiency on various design parameters are investigated. .Λ pulsed plane-wave model that takes into account the temporal profiles of the fields and the group velocity mismatch between pulses is constructed. This model is in good qualitative agreement with experimental measurements of a class-G SF-OPO.
Open Access
A self-doubling optical parametric oscillator based on aperiodically-poled lithium niobate
(IEEE, 2001) Kartaloǧlu, Tolga; Figen, Ziya Gürkan; Aytür, Orhan
A self-doubling optical parametric oscillator (SDOPO) having one-dimensional aperiodic grating structure based on a LiNbO3 crystal was constructed. The structure was designed to quasi-phase-match both second harmonic generation (SHG) and optical parametric oscillation (OPO) processes. The grating structure contained in the LiNbO3 crystal was based on the construction of a function by summing up two cosine functions with arbitrary phase and amplitude.
Open Access
Simultaneous optical parametric oscillation and sum-frequency generation within a single crystal for converting 1064 nm into 627 nm
(IEEE, 2005-07) Figen, Z. Gürkan; Aytür, Orhan
We report a 1064-nm pumped optical parametric oscillator based on a single KTiOAsO4 crystal that simultaneously generates the sum frequency of the pump and signal wavelengths, providing a 627 nm output with a high conversion efficiency.
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.