RESUMEN
We show that the direct modulation bandwidth of nano-cavity light emitting devices (nLEDs) can greatly exceed that of any laser. By performing a detailed analysis, we show that the modulation bandwidth can be increased by the Purcell effect, but that this enhancement occurs only when the device is biased below the lasing threshold. The maximum bandwidth is shown to be inversely proportional to the square root of the modal volume, with sub-wavelength cavities necessary to exceed conventional laser speeds.
RESUMEN
Optical buffering is a major challenge in realizing all-optical packet switching. In this paper we propose a new buffer called a multipleinput single-output FIFO (MISO-FIFO) optical buffer that supports several functions normally associated with electronic RAM. Our structure reduces the physical size of a buffer by up to an order of magnitude or more by allowing reuse of its basic optical delay line (ODL) elements. Moreover, by using controllable fractional delay lines (CFDLs) as the basic building block we are able to reduce t size and frequency of voids in the output of the buffer. We develop a Markov Chain (MC) model for the performance of our new buffering scheme, and demonstrate the advantages of our structure over buffer structures that use ODLs in terms of throughput and link utilization.
RESUMEN
Optical performance monitoring is an indispensable feature for optical systems and networks. In this paper, we propose the concept of optical performance monitoring through channel estimation by receiver signal processing. We show that in coherent-optical-orthogonal-frequency-division- multiplexed (CO-OFDM) systems, critical optical system parameters including fiber chromatic dispersion, Q value, and optical signal-to-noise ratio (OSNR) can be accurately monitored without resorting to separate monitoring devices.
RESUMEN
We explore the potential of chromatic dispersion and polarization-mode dispersion (PMD) mitigation using Viterbi equalization in 10 Gb/s nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) and differential quadrature phase-shift keying (NRZ-DQPSK) systems. We show through Monte Carlo simulations that using Viterbi equalization improves the performance of NRZ-OOK, NRZ-DPSK and NRZ-DQPSK receivers. For NRZ-DQPSK receiver with a Viterbi equalizer, the chromatic dispersion tolerance is about 5000 ps/nm and the 1st order PMD tolerance is about 160 ps at 3 dB OSNR penalty.
RESUMEN
We demonstrate an improved chromatic dispersion monitoring technique using a single RF monitoring tone. Compared to conventional techniques using a single RF monitoring tone, our proposed technique is able to monitor the sign of the residual dispersion and doubles the monitoring range. Our proposed technique utilizes the RF fading caused by chromatic dispersion and a two-detector dispersion monitor setup, where a dispersion offset is inserted before one of the detectors. The observed monitoring error is less than +/-35 ps/nm over a 1300 ps/nm monitoring range. A small power penalty less than 0.5 dB is observed due to the addition of the RF monitoring tone. Our technique is more than twice as accurate as the conventional technique.
RESUMEN
We propose and demonstrate a bidirectional optical add-drop multiplexer for use in single-fiber bidirectional networks. With effective use of multiport circulators, fiber-Bragg gratings, and a single amplifier element, the new structure can add and/or drop channels in both directions and achieves more than 16 dB of bidirectional gain. The device utilizes Bragg gratings and light absorber to remove Rayleigh backscattered and reflected light at the input stage.