Universal transmitter for wireless and optical access converged networks

Abstract

The integration of ultra-wideband (UWB)-over-fiber into passive optical network (PON) is of great interest as it benefits the high bandwidth capability from optical network technologies and the high flexibility from wireless network technologies. The later can only be done with a reasonable cost when a universal optical transmitter, which is capable of generation both UWB and PON signals, is available. Direct modulation of semiconductor laser was demonstrated to be suitable for high bit-rate PON systems, however the generation of UWB signals by this technique is still challenging. Using the chirp properties of directly modulated semiconductor lasers, UWB signals are generated. Different UWB signal waveforms and polarities are obtained. The received electrical spectra conform to the requirements of indoor UWB systems.

Generating 6thorder Gaussian derivative for UWBoF using directly modulated laser and accumulative chromatic dispersion of fiber

“…5. Principle of operation for generating monocycle and doublet pulses is ex plained in [4], [5] and [6]. Pulse pattern generator at 12.5 Gbps generates a 781.25 MHz driving electrical signal (PRBS 2 7 -1) with a fixed pattern of "1010 0000 0000 0000" for representing the logical '1' and "0000 0000 0000 0000" to represent logical '0'.…”

“…Since generating higher orders would be complicated, generation of first order Gaussian derivative (monocylce) and second order (doublet) have usually been reported in the microwave photonic research community [4]. As shown in Fig.…”

“…Obtained pulse after CML.As it is known and also mentioned in[4], because of the high chirp of our optical signal, chromatic dispersion introduced in optical fiber modifies the waveform, thereby 6 th order Gaussian derivative can be achieved after fiber transmission. Optical signal is converted to electrical through a photo detector (PD); the obtained pulse and its spectrum along with FCC mask are depicted inFig.…”

“…Experimental setup.When a Gaussian shaped driving signal is applied to chirped-man aged-laser (CML), as it is explained in[4], a monocycle pulse is expected at the output. Therefore, by applying the new pattern, a sinusoidal like pulse can be generated after CML.…”