Optical pulses generated by current modulation of semiconductor lasers are strongly frequency chirped. This effect has been considered pernicious for optical communications. We take advantage of this effect for the generation of ultrawideband microwave signals by using an optical filter to achieve chirp-to-intensity conversion. We also experimentally achieve propagation through a 20 km nonzero dispersion shifted fiber with no degradation of the signal at the receiver. Our method constitutes a prospective low-cost solution and offers integration capabilities with fiber-to-the-customer-premise systems.
We propose a novel line coding combination (Inverse RZ coding in downlink and RZ in uplink) that extends the reach of WDM Passive Optical Networks based on Reflective SOAs with no in-line amplification. We achieved full downstream remodulation even when feeding the reflective SOA with power levels as low as -35 dBm, thus increasing the system power budget. We experimentally assessed this scheme for a fully passive, full-duplex and symmetrical 1.25 Gb/s WDM-PON over a 80 km G.652 feeder.
We outline a novel method performing all-optical envelope detection of radio-frequency signals for radio-over-fiber links. A high frequency modulated signal with a slower-varying envelope is injected into a DFB laser which, due to gain suppression effects, recovers only the envelope of the optical signal. We characterize the DFB gain suppression effect in terms of injected signal wavelength and power level requirements. System performance is assessed, including experimental bit-error rate results; these illustrate successful envelope detection for a 20 GHz carrier with ASK modulation operating at 2.5 Gbit/second. Preliminary results at 5.5 Gbit/s show significant potential for application in hybrid optical-wireless communications networks.
First-known demonstration of an uncooled, free-running 1550 nm VCSEL at 10.7 Gb/s over 50 km PON uplink with 35 km SMF and 15 km inverse dispersion fiber, achieving 24 dB margin for 10 -9 BER.
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