The present disclosure relates to, e.g., devices, systems and methods of providing and/or manufacturing Raman lasers based on micro-ring and micro-racetrack resonators, including Raman lasers.
Generally, stimulated Raman scattering (“SRS”) has an extensive history since the development of the laser. Previously, the SRS effect at infrared frequencies has been established. This discovery was then described as a two-photon process with a full quantum mechanical calculation. To account for anti-Stokes generation and higher-order Raman effects, however, coupled-wave formalism was adopted to describe the stimulated Raman effect. Self-focusing was later included to account for the much larger gain observed in SRS. These understandings facilitated the study and design of Raman amplifiers and lasers. For example, low-threshold microcavity Raman lasers have been demonstrated in silica micro spheres and micro disks using excited whispering gallery modes (“WGMs”). Such devices can play an important role in the developing technology of photonic integrated circuits.
Because silicon is being considered as a possible platform for photonic integrated circuits, silicon-based photonic devices have been increasingly researched. Microscopic passive silicon photonic devices such as bends, splitters, and filters have been developed. Active functionalities in highly integrated silicon devices have been studied, such as optical bistability due to the nonlinear thermal-optical effect and fast all-optical switching with two-photon absorption.
Silicon-based Raman amplifiers and lasers also have been analyzed. The bulk Raman gain coefficient gR in silicon is likely about 104 times higher than in silica. Light generation and amplification in planar silicon waveguides with Raman effects have been reviewed. Raman lasing using a silicon waveguide as the gain medium has been demonstrated, where the ring laser cavity is formed by, e.g., an 8-m-long optical fiber. A Raman laser using an S-shaped 4.8-cm-long silicon waveguide cavity with multi-layer coatings has also been reported, which can be integrated onto CMOS-compatible silicon chips.
There have been certain developments of tunable laser devices and methods of manufacturing such devices. For example, U.S. Patent Publication No. 2006/0050744 (the “744 Publication”), the entirety of the disclosure of which is explicitly incorporated by reference herein, describes various embodiments of a laser device that can include a layer of photonic crystal having a lattice of air-holes with defects that form an optical waveguide. According to some embodiments described the 744 Publication, the waveguide can have a cross-sectional area having dimensions in sub-wavelength ranges and which can be perpendicular to the propagation direction of light in the waveguide. In some embodiments described in the 744 Publication, the waveguide can pump light and output Stokes light through Raman scattering. The frequencies of the pump light and the Stokes light can include, e.g., slow group velocity modes of the pump light and Stokes light in the waveguide.
Further, there has been development of microscopic low-threshold Raman amplification and lasing devices on a monolithic silicon chip, which devices can support the development towards efficient, all-optical photonic integrated circuits. For example, U.S. Patent Publication No. 2007/0025409 (the “409 Publication”), the entirety of the disclosure of which is explicitly incorporated by reference herein, describes various embodiments of all-optical on-chip signal amplification and lasing. In particular, some embodiments of the 409 Publication implement Raman amplification and lasing devices using on-chip micro ring resonators coupled with waveguides in monolithic silicon. Some embodiments of the 409 Publication also include methods of manufacturing such devices. According to some embodiments of the 409 Publication, lasers can be designed with geometries so that WGM resonant frequencies of the micro ring resonator match the pump-Stokes frequency spacing of SRS in monolithic silicon. Therefore, in some embodiments of the 409 Publication, one or more pairs of pump and Stokes light can form WGMs in the micro ring resonator.
In the event of a conflict between the teachings of the application and those of the incorporated documents, the teachings of the application shall control.
Despite these advances, various improvements, such as, e.g., devices having a smaller waveguide and a high surface area to volume ratio leading to, e.g., a reduced carrier lifetime can be beneficial. Thus, it would be beneficial to reduce and/or eliminate the need for external biased voltage so as to reduce carrier lifetime.
Some embodiments of the present disclosure described herein include a device which is structured to receive at least one electro-magnetic radiation including at least one resonator arrangement which has a distance from one edge thereof to another edge thereof which is at most approximately a wavelength of the at least one electro-magnetic radiation that impacts the at least one resonator arrangement. The at least one resonator arrangement can be configured to generate a Raman radiation when impacted by a further electro-magnetic radiation, for example. In some embodiments, the at least one resonator arrangement can solely generate the Raman radiation which is lasing.
Certain embodiments of the Raman radiation which is lasing can be generated by the at least one resonator arrangement in a continuous mode and/or a pulsed lasing mode. In some embodiments, the at least one resonator arrangement can generate the Raman radiation which is lasing without a use of an external electrical driver. The external electrical driver can be a p-i-n diode arrangement, for example. According to some embodiments, the resonator arrangement(s) can have a carrier lifetime which is at most about 1 nanosecond. In some embodiments, the carrier lifetime can be at most about 0.5 nanosecond. The electro-magnetic radiation(s) can be applied to the resonator arrangement(s) so that carriers within the resonator arrangement(s) are purged at a surface of the at least one resonator arrangement, for example. According to some embodiments, the carriers can be completely purged immediately at a surface of the resonator arrangement(s).
In addition, provided herein are certain embodiments of a device according to the present disclosure which can be structured to receive at least one electro-magnetic radiation including at least one waveguide arrangement. Such exemplary waveguide arrangement(s) can have a width that is at most approximately a wavelength of the electro-magnetic radiation(s) that can impact the waveguide arrangement(s). The waveguide arrangement(s) can be configured to generate a Raman radiation when impacted by a further electro-magnetic radiation, for example. In some embodiments, the waveguide arrangement(s) can include at least one photonic crystal arrangement, which can be structured to produce the Raman radiation at a slow-group velocity of a propagation of at least one of the Raman radiation or the at least one elector-magnetic radiation, for example. The resonator arrangement(s) can have a first portion extending along one axis, and a second portion which has at least (i) a first section which extends parallel to the first portion, and (ii) a second section which is distanced further from the first portion than the first section.
In addition, described herein are certain embodiments of methods and/or procedures according to the present disclosure for manufacturing a lasing device, which can include, e.g., providing a silicon micro-ring with a predetermined radius and a predetermined first cross-sectional dimension; creating a silicon waveguide with a predetermined second cross-sectional dimension; and disposing the silicon micro-ring from the silicon waveguide at a predetermined distance. The predetermined distance, radius, first cross-sectional dimension, and second cross-sectional dimension can be configured so that at least one first whispering gallery mode resonant frequency of the silicon micro-ring and at least one second whispering gallery mode resonant frequency of the silicon micro-ring can be separated by an optical phonon frequency of silicon, for example. In some embodiments, the lasing device can include at least one resonator arrangement which has a distance from one edge thereof to another edge thereof which is at most approximately a wavelength of at least one electro-magnetic radiation that impacts the at least one resonator arrangement. The resonator arrangement(s) can be configured to generate a Raman radiation when impacted by a further electro-magnetic radiation, for example.
According to some embodiments, the cross-sectional dimension of the silicon waveguide and a surface area to volume ratio can be configured to provide a reduced carrier lifetime. For example, the cross-sectional dimension of the silicon waveguide can have a submicron meter width and a submicron meter height. Embodiments of methods and/or procedures according to the present disclosure can further include displaying and/or storing information associated with the lasing device, manufacturing the lasing device and/or using the lasing device in a storage arrangement in a user-accessible format and/or a user-readable format.
A method for manufacturing a lasing device having a silicon micro-ring coupled with a silicon waveguide in accordance with another embodiment of the present disclosure is also described herein. Some embodiments of such methods can include, e.g., determining (i) a radius and a first cross-sectional dimension of the silicon micro-ring, (ii) a second cross-sectional dimension of the silicon waveguide, and (iii) a distance between the silicon micro-ring and the silicon waveguide, so that at least one first whispering gallery mode resonant frequency of the silicon micro-ring and at least one second whispering gallery mode resonant frequency of the silicon micro-ring are separated by an optical phonon frequency of silicon. Some embodiments can further include, e.g., creating the silicon micro-ring with the determined radius and the determined first cross-sectional dimension, creating the silicon waveguide with the determined second cross-sectional dimension, and disposing the silicon micro-ring from the silicon waveguide at the determined distance.
These and other objects, features and advantages of the present invention will become apparent upon reading the following detailed description of exemplary embodiments of the present disclosure, when taken in conjunction with the appended claims.
Further objects, features and advantages provided by the present disclosure will become apparent from the following detailed description taken in conjunction with the accompanying figures showing illustrative embodiments, in which:
a) is a silicon waveguide cross-section of a micro-racetrack in accordance with some embodiments of the present disclosure,
a) and 3(b) are graphs illustrating enhancement of spontaneous Raman scattering in a micro-racetrack resonator in accordance with certain embodiments of the present disclosure;
Throughout the figures, the same reference numerals and characters, unless otherwise stated, are used to denote like features, elements, components or portions of the illustrated embodiments. Moreover, while the present disclosure will now be described in detail with reference to the accompanying figures, it is done so in connection with the illustrative embodiments. It is intended that changes and modifications can be made to the described embodiments without departing from the true scope and spirit of the present disclosure.
Provided and described herein are, e.g., devices, systems and methods of manufacturing Raman lasers based on micro-ring and micro-racetrack resonators. Some embodiments in accordance with the present disclosure provide, e.g., devices and methods of manufacturing all-silicon Raman lasers based on micro-ring and micro-racetrack resonators.
According to some embodiments of the present disclosure, a device for generating a laser beam can be provided. For example, certain embodiments of the device can include, e.g., a silicon micro-ring having a radius and a first cross-sectional dimension; and a silicon waveguide having a second cross-sectional dimension. The waveguide can be disposed at a predetermined distance from the exemplary micro-ring. The distance, the radius, the first cross-sectional dimension, and the second cross-sectional dimension can be configured and/or arranged so that at least one first whispering gallery mode resonant frequency of the silicon micro-ring and at least one second whispering gallery mode resonant frequency of the silicon micro-ring are separated by an optical phonon frequency of silicon.
According to some embodiments of the present disclosure, a device for generating a laser beam is provided that can include, e.g., a layer of photonic crystal having a lattice of air-holes with defects that form an optical waveguide with a cross-sectional area having dimensions in sub-wavelength ranges. The cross-sectional area can be perpendicular to the propagation direction of the electro-magnetic radiation (e.g., light) in the waveguide. The waveguide can receive pump light and output Stokes light through Raman scattering.
Some embodiments according to the present disclosure also provide a device for generating a laser beam that can include, e.g., a photonic crystal made from silicon that can have air-holes forming a pair of optically coupled cavities having geometries that can be substantially the same to one another. The cavities can be defined to cause a frequency-splitting difference between a frequency of pump light and a frequency of Stokes light to correspond to an optical phonon frequency in silicon through Raman scattering, for example.
According to further embodiments of the present disclosure, a device for generating a laser beam is provided that can include, e.g., a layer of photonic crystal having a lattice of air-holes and at least one cavity formed by defects in the lattice of air-holes. The cavity can have a surface area on a surface of the layer. The dimensions of the surface area can be in the range of, e.g., several micro-meters. The cavity can output Stokes light in response to pump light through Raman scattering, for example.
In some embodiments of a device in accordance with the present disclosure, including some of those devices described herein for example, the cross-sectional dimension of the waveguide can be small and the surface area to volume ratio can be high, which can lead to a reduced carrier lifetime. Thus, a need for external biased voltage to reduce carrier lifetime can be eliminated, for example. The cross-sectional dimension of the waveguide can have a submicron meter width and height. For example, the width can be within a range of, e.g., approximately 0.1 μm to approximately 0.9 μm, such as, e.g., approximately 0.45 μm. The height can also be within the range of, e.g., approximately 0.1 μm to approximately 0.9 μm, such, e.g., as approximately 0.25 μm, for example.
Some embodiments of the device can provide a relatively low-threshold continuous-wave Raman silicon laser based on a 3-centimeter-long racetrack cavity. For example, the micrometer-size rib waveguide can have an effective modal area of 1.6 μm2. A p-i-n diode structure can be used to, e.g., minimize nonlinear losses due to two-photon absorption (TPA) induced free-carrier absorption (FCA) and achieve low lasing threshold, for example. By reverse-biasing the diode with a voltage of, e.g., 10 to 20 volts, such as 25 volts, the effective free carrier lifetime τfc can be reduced from, e.g., 10 to 20 nanoseconds, such as, 15 nanoseconds to, e.g., 0.1 to 0.9 nanoseconds, such as to below 0.4 nanoseconds, for example.
Micro-ring and micro-racetrack resonators used in accordance with the present disclosure can have cross section dimensions of, e.g., 0.45 μm (W) by 0.25 μm (H), with an effective modal area of approximately 0.1 μm2, which can be more than 10 times smaller in comparison to other embodiments, such as those described herein. The τfc can be significantly reduced to a level below 1 nanosecond, such as, e.g., approximately 0.5 nanoseconds for micro-ring resonators. Such embodiments can provide the device to lase, e.g., without introducing an external p-i-n diode to drive the carriers away, for example. According to embodiments with a micro-ring having a diameter of 10 μm, the effective modal volume can be, e.g., approximately 7 μm3. According to further embodiments with, e.g., a 3-mm-long micro-racetrack, the effective modal volume can be, e.g., approximately 2000 μm3, for example.
a)-1(c) illustrate various views of a cross-section of a device 101 according to certain embodiments of the present disclosure that has been configured and arranged to provide enhancement of spontaneous emission, for lasing, in micro-racetracks. As shown in
b) illustrates a micro-racetrack 111 of the device 101 and
According to certain embodiments, a low power tunable laser source which can include the device 101 can be amplified using an erbium doped fiber amplifier to be used as the Raman pump. Such exemplary amplification can be to a power in the range of, e.g., approximately 200 mW to approximately 500 mW, such as, e.g., approximately 250 mW. For example, the pump can be coupled into the resonator using a tapered lensed fiber, for example. The transmitted pump and the emitted Stokes can be coupled to the resonator using, e.g., a similar lensed fiber. A wavelength division multiplexer can then be used to separate the pump wavelength from the Stokes wavelength. Both the pump and the emitted stokes can be measured using, e.g., a photo detector. For example, the waveguide loss can be in the range of, e.g., approximately 2 dB/cm to approximately, 4 dB/cm, such as approximately 3 dB/cm. The coupling loss can be in the range of, e.g., approximately 6 dB to approximately 10 dB, such as, e.g., approximately 8 dB. Thus, for example, a coupled input power in the range of, e.g., approximately 30 mW to approximately 50 mW, such as, e.g., approximately 40 mW, can be provided in accordance with some embodiments of the present disclosure.
Further described herein are examples of lasing characteristics analysis procedure according to certain exemplary embodiment of the present disclosure for silicon Raman lasers based on micro-ring and micro-racetrack resonators using a coupled-mode theory (CMT) model or procedure. Other embodiments can include, for example, data relating to a spontaneous emission enhancement of Raman scattering in micro-racetrack resonators, for example.
For example, according to certain embodiments of the present disclosure, lasing input-output characteristics and lasing a threshold can be analyzed and determined by using a coupled-mode theory framework. Loss rates of cavity modes due to, e.g., radiation, linear material absorption, two-photon absorption and free-carrier absorption can be included in the CMT model. A refractive index shift from, e.g., Kerr effect, free-carrier dispersion and thermal dispersion can also be considered in some embodiments. Equations in accordance with certain embodiments of the present disclosure can be numerically integrated to, e.g., describe the dynamical behavior of pump-Stokes interactions in micro-ring and micro-racetrack resonators that can support two-mode frequencies of, e.g., 15.6 THz, which can be desired in some embodiments of the present disclosure.
Raman lasing in silica-based high-Q whispering gallery mode resonators, such as, e.g., microspheres, microdisks and microtoroids, can have relatively low and/or ultralow lasing thresholds. In addition, continuous-wave silicon Raman lasers can have centimeter-size waveguide cavities and racetrack cavities with significantly reduced free carrier lifetime. According to certain embodiments of the present disclosure, a reverse-biased p-i-n diode embedded in a silicon waveguide can be used. The bulk Raman gain coefficient gR can be, e.g., 103 to 104 times larger in silicon than in silica, for example. The enhanced stimulated Raman amplification and relatively low and/or ultralow threshold Raman lasing in high-Q/Vm photonic crystal nanocavities and slow-light photonic crystal waveguides can be used. According to some embodiments according to the present disclosure, Raman lasers can be provided which can be based on micrometer-size whispering gallery mode resonators such as, e.g., micro-ring and micro-racetrack configurations that can reduce free carrier lifetime and achieve Raman lasing without an external p-i-n diode for driving the free carrier away.
As also shown in
In order to determine the effect that a resonator according to certain embodiments of the present disclosure can have on an emitted Stokes intensity, a pump laser wavelength can be scanned through multiple free-spectral ranges while the emitted stokes power and transmitted pump power is recorded. This exemplary information and/or data can be stored on, e.g., a computer-readable medium and/or computer-accessible medium that can be part of, e.g., a computing arrangement and/or processing arrangement, which can include and/or be interfaced with computer-accessible medium having executable instructions thereon that can be executed by the computing arrangement and/or processing arrangement. These arrangements can include and/or be interfaced with, but not limited to) a storage arrangement, which can be or include memory such as, e.g., RAM, ROM, cache, CD ROM, etc., a user-accessible and/or user-readable display, and user input devices, a communication module and other hardware components forming a system to, e.g., design, provide and/or manufacture a lasing device in accordance with certain embodiments of the present disclosure, and/or analyze information and/or data associated with the device and/or a method of manufacturing and/or using the device accordance with certain embodiments of the present disclosure, for example.
For example,
For the exemplary resonance shown in the graph of
A method of manufacturing a lasing device can be provided according to certain embodiments of the present disclosure. For example, a summary of such exemplary method can be as follows:
1) create and/or provide a silicon micro-ring with a predetermined radius and a predetermined first cross-sectional dimension;
2) create and/or provide a silicon waveguide with a predetermined second cross-sectional dimension; and
3) dispose, provide or arrange the silicon micro-ring from the silicon waveguide at a predetermined distance.
According to certain embodiments of the present disclosure, the predetermined distance, the predetermined radius, the predetermined first cross-sectional dimension, and the predetermined second cross-sectional dimension can be determined and/or configured so that, e.g., at least one first whispering gallery mode resonant frequency of the silicon micro-ring and at least one second whispering gallery mode resonant frequency of the silicon micro-ring are separated by an optical phonon frequency of silicon, for example.
For example,
Further, a method of manufacturing a lasing device having a silicon micro-ring coupled with a silicon waveguide according to certain other embodiments of the present disclosure can be provided. For example, a summary of such exemplary method can be as follows:
1) determine (i) a radius and a first cross-sectional dimension of the silicon micro-ring, (ii) a second cross-sectional dimension of the silicon waveguide, and (iii) a distance between the silicon micro-ring and the silicon waveguide, so that at least one first whispering gallery mode resonant frequency of the silicon micro-ring and at least one second whispering gallery mode resonant frequency of the silicon micro-ring are separated by an optical phonon frequency of silicon;
2) create and/or provide the silicon micro-ring with the determined radius and the determined first cross-sectional dimension;
3) create and/or provide the silicon waveguide with the determined second cross-sectional dimension; and
4) dispose, provide or arrange the silicon micro-ring from the silicon waveguide at the determined distance.
For example,
For example, additional embodiments of the present disclosure provide another method of manufacturing a laser device. A summary of such exemplary method includes the following procedure:
1) form or provide a layer of silicon; and
2) etch the silicon layer to form photonic crystal having a lattice of air-holes with defects that form an optical waveguide having a cross-sectional area with dimensions that are in sub-wavelength ranges.
For example, the cross-sectional area of the waveguide can be perpendicular to the propagation direction of light in the waveguide, which can receive pump light and output Stokes light through Raman scattering, for example.
In addition, a further method of manufacturing a laser device according to certain exemplary embodiments of the present disclosure can be provided that can include the following procedure:
1) form or provide a layer of silicon; and
2) etch the silicon layer to form a photonic crystal having air-holes and to form a pair of optically coupled cavities having geometries that are substantially identical to one another.
The cavities can be defined to cause a frequency-splitting difference between a frequency of pump light and a frequency of Stokes light to correspond to an optical phonon frequency in silicon through Raman scattering, for example.
Still another method of manufacturing a laser device according to certain exemplary embodiments of the present disclosure can be provided that includes the following procedures:
1) form and/or provide a silicon layer; and
2) etch the silicon layer to form photonic crystal having a lattice of air-holes; and forming at least one cavity shaped by defects in the lattice of air-holes.
The cavity can have a surface area on a surface of the layer. According to some embodiments, the dimensions of the surface area can be within several micro-meter ranges. The cavity can output Stokes light in response to pump light through Raman scattering, for example.
In some embodiments of the device manufactured by the exemplary method in accordance with the present disclosure, including one or more of the exemplary methods described herein, for example, the cross-sectional dimension of the waveguide can be small and the surface area to volume ratio can be high, which can lead to a reduced carrier lifetime. Thus, it is possible to reduce or even eliminate the need for an external biased voltage to reduce carrier lifetime, for example. The cross-sectional dimension of the waveguide can have a submicron meter width and height. For example, the width can be within a range of, e.g., approximately 0.1 μm to approximately 0.9 μm, such as, e.g., approximately 0.45 μm. The height can also be within the range of, e.g., approximately 0.1 μm to approximately 0.9 μm, such, e.g., as approximately 0.25 μm, for example.
Some embodiments in accordance with the present disclosure, can including some of those described herein, can be combined with the subject matter disclosed in the 744 Publication and/or the 409 Publication, the entirety of the disclosures of which have been explicitly incorporated by reference herein, and thus shall be considered as part of the present disclosure and application.
Additionally, embodiments of computer-accessible medium described herein can have stored thereon computer executable instructions for designing, manufacturing and/or using a lasing device in accordance with the present disclosure. In addition, such computer-accessible medium can be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, and as indicated to some extent herein above, such computer-accessible medium can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer. When information is transferred or provided over a network or another communications link or connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computer, the computer properly views the connection as a computer-accessible medium. Thus, any such a connection is properly termed a computer-accessible medium. Combinations of the above should also be included within the scope of computer-accessible medium.
Computer-executable instructions can include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device or other devices (e.g., mobile phone, personal digital assistant, etc.) with embedded computational modules or the like configured to perform a certain function or group of functions.
Those having ordinary skill in the art will appreciate that embodiments according to the present disclosure can be practiced with network computing environments with many types of computer system configurations, including personal computers, hand-held devices, multi-processor systems, microprocessor-based or programmable electronics and devices, network PCs, minicomputers, mainframe computers, and the like. Embodiments in accordance with the present disclosure can also be practiced in distributed computing environments where tasks are performed by local and remote processing devices that are linked (either by, e.g., hardwired links, wireless links, or a combination of hardwired and wireless links) through a communications network. In a distributed computing environment, program modules can be located in both local and remote memory storage devices.
The foregoing merely illustrates the principles of the present disclosure. Various modifications and alterations to the described embodiments will be apparent to those having ordinary skill in the art in view of the teachings herein. It will thus be appreciated that those having ordinary skill in the art will be able to devise numerous devices, systems, arrangements, computer-accessible medium and methods which, although not explicitly shown or described herein, embody the principles of the present disclosure and are thus within the spirit and scope of the present disclosure. As one having ordinary skill in the art shall appreciate, the dimensions, sizes and other values described herein are examples of approximate dimensions, sizes and other values. Other dimensions, sizes and values, including the ranges thereof, are possible in accordance with the present disclosure.
It will further be appreciated by those having ordinary skill in the art that, in general, terms used herein, and especially in the appended claims, are generally intended as open. In addition, to the extent that the prior art knowledge has not been explicitly incorporated by reference herein above, it is explicitly being incorporated herein in its entirety. All publications referenced above are incorporated herein by reference in their entireties. In the event of a conflict between the teachings of the application and those of the incorporated documents, the teachings of the application shall control.
The present application claims priority from U.S. patent application No. 61/081,863, filed Jul. 18, 2008, the entire disclosure of which is hereby incorporated herein by reference in its entirety.
The present disclosure was developed, at least in part, using Government support under Grant No. 0622069 awarded by the National Science Foundation. Therefore, the Federal Government has certain rights in the present disclosure.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US09/51117 | 7/20/2009 | WO | 00 | 6/15/2011 |
Number | Date | Country | |
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61081863 | Jul 2008 | US |