A new extended-reach GPON for rural areas using distributed Raman amplifiers is proposed and demonstrated. Symmetric 2.5-Gb/s bidirectional transmission is achieved for 32 subscribers over 60-km reach, without using any active extender.
We report long-reach PON systems utilizing distributed Raman amplification for rural and remote areas.Symmetric 2.5-Gb/s bidirectional transmission is achieved over 60-km reach. We also discuss the practical deployment issues and economics of long-reach PON.
We have demonstrated an all-optical time and wavelength switch using cascaded second-order nonlinearities of a PPLN waveguide incorporated in a fiber based loop interferometer. Switching efficiency as high as 90.3% has been achieved. OCIS codes: (070.4340) Nonlinear optical signal processing; (060.4510) Optical communications
IntroductionThe increase in the demand for optical transmission bandwidth has led to a great interest in developing wavelengthdivision-multiplexing technologies in future optical packet switched networks [1]. Recent years, cascaded second order nonlinearity of periodically poled Lithum Niobate (PPLN) waveguide has been explored for its applications in optical processing of high speed data signals [2,3]. With the recent advances in the fabrication of PPLN devices, higher conversion efficiency (as high as 0 dB) [4] as well as polarization independent wavelength conversion [5] had been achieved already. With their advantages of low noise, ease of integration with devices and higher effective nonlinear coefficients, PPLN based devices have good prospects for high speed optical signal processing applications. In this work, we have demonstrated an all-optical switch using cascaded sum and difference frequency generation (cSFG/DFG) [2,6] at a PPLN waveguide incorporated in a fiber loop interferometer. The switching efficiency of the proposed scheme has been investigated through a pump-probe experiment. Fig. 1 (a) is the schematic illustration of our proposed all-optical switch which exploits a fiber loop interferometer incorporated with a PPLN waveguide (PPLN-LI). The role of the PPLN is to introduce phase shift to the clockwise propagating packet without affecting the counter-propagating packet, which can be achieved due to the fact that cSFG/DFG is directional inside the PPLN [5]. It should be noted that by taking the advantage of dependence of nonlinear interactions on the direction of propagation, the position of the PPLN waveguide inside the loop could be made arbitrary, i.e. not like other loop interferometers requiring precise location of the phase-shifting element. Initially, in the absence of the gating pump signal, all the incoming packets are switched out to the Port 1 via the circulator. When the gating pump signal is launched, due to the cSFG/DFG process, the optical packets propagating clockwise inside the PPLN-LI and falling within the switching window established by the gating pump signal will experience a phase shift. Consequently, this leads to a phase difference between clockwise and counterclockwise propagating packets. Therefore, the optical packets gated by the gating optical signal can be switched out to the Port 2 while the rest of the optical packets transmitted to the original Port 1.
Principle and experiment Shown in
By exploiting cascaded second-order nonlinearities of a PPLN waveguide incorporated in a fibre based loop interferometer, we have experimentally demonstrated an optically controlled time and wavelength switch with a switching efficiency as high as 90.3%.
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