ABSTRACT
We report on a record spectral efficient terahertz communication system using a coherent radio-over-fiber (CRoF) approach. High spectral efficient back-to-back and wireless THz transmission around 325 GHz is experimentally demonstrated using a 64-QAM-OFDM modulation format and a 10 GHz wide wireless channel resulting in a data rate of 59 Gbit/s.
ABSTRACT
This work demonstrates the feasibility of the generation of an RF direct-detection vector signal using optical in-phase/quadrature-phase (I/Q) upconversion. The advantage of the proposed transmitter is that no electrical mixer is needed to generate the RF signal. Therefore, I/Q data of RF signals are processed at baseband at the transmitter, which is independent of the carrier frequency of the generated RF signal. A 10 Gb/s 16 quadrature amplitude modulation signal is experimentally demonstrated. Following transmission over a 50 km single-mode fiber, the power penalty is negligible. Moreover, I/Q imbalance of the proposed transmitter is studied and compensated by digital signal processing, which is both numerically and experimentally verified.
ABSTRACT
This work describes a proposed 60-GHz radio-over-fiber (RoF) system employing a frequency sextupling optical up-conversion scheme. Based on the modified single sideband modulation scheme, spectrally efficient vector signals were transmitted with no performance degradation due to dispersion-induced fading. Wavelength-division- multiplexed optical up-conversion can be realized using the proposed system. Since the required transmitter bandwidth is significantly reduced, radio-frequency components with lower bandwidth and higher reliability can be utilized. Both 13.75-Gb/s QPSK-OFDM and 20.625-Gb/s 8QAM-OFDM signals were experimentally demonstrated. After transmission over 25-km of standard single mode fiber, no significant received power penalty was observed.
ABSTRACT
This work demonstrates the feasibility of a full duplex Radio-over-fiber (RoF) link employing multi-level OFDM signal via a single-electrode Mach-Zehnder modulator and wavelength reuse for uplink utilizing a reflective semiconductor optical amplifier (RSOA). A High spectral efficiency 5-Gb/s 16-QAM OFDM signal with frequency multiplication for the RoF downstream link is demonstrated, and negligible penalty is achieved after 25-km standard single mode fiber transmission. Furthermore, wavelength reuse for a 1.25-Gb/s OOK signal via a RSOA for the upstream link is also demonstrated with a receiver penalty of less than 0.5 dB following 25-km SMF transmission.
ABSTRACT
This study proposes a full duplex 60-GHz band radio-over-fiber (RoF) link using a modified tandem single sideband (TSSB) modulation scheme with frequency doubling. Based on the modified TSSB modulation scheme, no dispersion induced fading is observed; high spectral efficiency vector signal can be utilized; and wavelength reuse can also be achieved. Both single carrier 8-QAM and QPSK-OFDM signals for down-link transmissions are experimentally demonstrated. After transmission of 50-km SSMF, no significant receiver power penalties are observed. Wavelength reuses with 1.25-Gb/s OOK using a reflective semiconductor optical amplifier (RSOA) for up-link transmission are also demonstrated. After transmission of 50-km SSMF, no significant receiver power penalties are also observed.
Subject(s)
Optical Fibers , Telecommunications/instrumentation , Computer-Aided Design , Equipment Design , Equipment Failure Analysis , Microwaves , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
This work proposes a cost-effective, continuously tunable and filterless optical millimeter-wave (MMW) signal generation employing frequency octupling. Optical MMW signals with 30-dB undesired sideband suppression ratios can be obtained. Since no optical filtering is required, the proposed system can be readily implemented in wavelength-division-multiplexing (WDM) systems. V-band 60-GHz and W-band 80-GHz optical MMW signals are experimentally demonstrated. Because of the high undesired sideband suppression ratio, 60-GHz waveform with 50% duty cycle is observed. The single-sideband (SSB) phase noise of the generated 60-GHz signal is -73 dBc/Hz at 10 kHz. The proposed system is a viable solution for the future ultra-high frequency MMW applications up to 320 GHz using the external modulator with a limited bandwidth of 40 GHz.
Subject(s)
Optical Devices , Refractometry/instrumentation , Telecommunications/instrumentation , Computer-Aided Design , Equipment Design , Equipment Failure Analysis , Filtration , Microwaves , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
To the best of our knowledge, a novel photonic architecture to generate vector signals at microwave/millimeter-wave bands employing an optical frequency quadrupling technique based on an external dual-parallel modulator is proposed for the first time. A 312.5 MSym/s quadruple phase-shift keying signal at 25 GHz is experimentally demonstrated using properly precoding driving signal at 6.25 GHz, and optical power penalty is negligible following 50 km single-mode fiber transmission.
ABSTRACT
This work experimentally demonstrates the efficacy of a radio-frequency phase shifter using a distributed feedback laser in a microwave transport system. Phase shifts of about 101 degrees are obtained at 8.75 GHz. The proposed phase shifter can amplify microwave signals and thereby improve transmission performance. Additionally, a similar single sideband modulation can be generated by the phase shifter. Experimental results indicate that the proposed phase shifter can be used in future long-distance microwave transport systems and all optical inverters.
Subject(s)
Lasers , Telecommunications/instrumentation , Computer-Aided Design , Equipment Design , Equipment Failure Analysis , Feedback , Microwaves , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
This work presents an optical up-conversion system with frequency quadrupling for wavelength-division-multiplexing (WDM) communication systems using a dual-parallel Mach-Zehnder modulator without optical filtering. Four-channel 1.25-Gb/s wired fiber-to-the-x (FTTx) and wireless radio-over-fiber (RoF) signals are generated and transmitted simultaneously. Moreover, the decline in receiver sensitivities due to Mach-Zehnder modulator bias drifts is also investigated. Receiver power penalties of the 20-GHz up-converted WDM signals and baseband (BB) FTTx signals are less than 1 dB when bias deviation voltage is less the 20% of the half-wave voltage. After transmission over a 50-km SSMF, the receiver power penalties of both the BB and 20-GHz RF OOK signals are less than 1 dB. Notably, 60-GHz optical up-conversion can be achieved using 15-GHz radio frequency (RF) components and equipment.
ABSTRACT
This investigation demonstrates the generation of OFDM-RoF signal using frequency doubling technique for the first time, to the author's best knowledge. The 4-Gb/s OFDM signal using 16-QAM format modulated on each subcarrier at a center frequency of 19GHz is experimentally demonstrated. Benchmarked against the OOK format, the 16-QAM OFDM format has the higher spectral efficiency with a sensitivity penalty of less than 2.6 dB. After transmission over 50-km single mode fiber, the power penalties of RF OOK and OFDM signals are less than 0.5 dB.
