Orthogonal frequency-division multiplexing in wireless communication systems with multimode fiber feeds

The feasibility of using multimode fiber as an inexpensive cell feed in broad-band indoor picocellular systems is investigated in this paper. The performance of coded orthogonal frequency-division multiplexing (OFDM) for a variety of multimode fiber profiles, including stepped index and -profile graded index fibers, is assessed. In addition to its ability to perform well in a frequency- selective multipath environment, OFDM is shown to offer good protection against the frequency selectivity of a dispersive multimode fiber. Data rates in excess of 100 Mb/s (without equalization) over a multimode fiber channel are possible, whereas they may be limited to some 20–30 Mb/s using conventional ASK modulation

Self-oscillating optical comb generator based on optoelectronic oscillator

This work is focused on two promising concepts of microwave photonics- optoelectronic oscillators and optical frequency comb generators, and their use to generate a self-oscillating optical comb. In particular we develop a recirculating loop topology in which a Mach-Zehnder modulator is modulated recursively via a secondary loop that acts as a self-homodyne input

Optoelectronic oscillator based on class AB photonic link

An optoelectronic oscillator topology based on a class AB analogue optical link is proposed. The motivation for this approach is based on the unique property of class AB links for mitigating both shot noise and relative intensity noise contributions. The class AB optoelectronic oscillator is compared with a conventional single loop optoelectronic oscillator

High-Q wavelength division multiplexed optoelectronic oscillator based on a cascaded multi-loop topology

A WDM optoelectronic oscillator (OEO) based on a cascaded optical multi-loop configuration and multiple photodiodes is proposed and demonstrated experimentally. By employing up to three lasers widely separated in wavelength along with two cascaded multi-loop fiber sections and two photodiodes, we demonstrate OEO topologies that scale up to six effective loops revealing an ultra-high quality factor in excess of 1010 and a phase noise performance down to −119 dBc/Hz at 10 kHz offset

Ultra-high-Q optoelectronic oscillator based on bilaterally coupled loops

An optoelectronic oscillator (OEO) based on bilateral coupling between two individual optoelectronic loops is demonstrated. The resulting OEO has two modes of operation, in which the individual loops either oscillate or act as IIR filters. A Q-factor greater than 1010 at 5.8 GHz is observed

Multi-core Fiber Based Mm-Wave Generation, Radio-over- Fiber, and Power-over-Fiber

We propose a multi-core fiber (MCFs) based concept which simultaneously use to generate millimeter wave (mm-wave) signal; a radio over fiber link; and a power over fiber link. In the proposed system, some cores of MCFs are used to generate mm-wave signal using an optoelectronic oscillator (OEO) topology, few of the cores are used to transport data modulated mm-wave signal through radio-over-fiber (RoF) technology while others are used to transmit optical power for biasing the amplifier in the remote antenna unit with help of power over fiber (PoF) technology and photonic power converter in a small cell architecture of the future 5G technology

Cascaded Microwave Photonic Filters for Side Mode Suppression in a Tunable Optoelectronic Oscillator applied to THz Signal Generation & Transmission

We demonstrate experimentally an optoelectronic oscillator (OEO) in which high side-mode suppression is achieved by cascading a phase modulator-based single passband tunable microwave photonic (MWP) filter with an optoelectronic feedback loop-based infinite impulse response (IIR) MWP filter. The OEO provides an RF oscillation that can be tuned from 6.5 GHz to 17.8 GHz with a phase noise lower than -103 dBc/Hz. Experimental results show that inclusion of the IIR section leads to a 20 dB reduction of phase noise close to the carrier and an increase of 10 dB in side mode suppression, compared to the equivalent OEO without an IIR section. The OEO was used to drive an optical frequency comb generator to generate a THz signal at 242.6 GHz by optical heterodyning; inclusion of the IIR section increases suppression of the side modes neighboring the THz carrier. A radio over fiber link was then implemented at a 242.6 GHz carrier frequency, with transmission of a 24 Gbps signal over 40 km of fiber and a 30 cm wireless path at a bit error rate below the forward error correction limit. The proposed system may be applied to frequency reconfigurable THz links and radars

Tunable THz Signal Generation and Radioover-Fiber Link based on an Optoelectronic Oscillator-driven Optical Frequency Comb

We propose and demonstrate experimentally a photonic THz signal generation technique based on a tunable optoelectronic oscillator (OEO), and its application in a radio over fiber (RoF) link. The OEO's is tuned by varying the bandwidth of a tunable optical bandpass filter (TOBF) that is cascaded with a phase modulator (PM). The resulting tunable microwave photonic filter is used to generate OEO oscillations from 6.58 GHz up to 18.36 GHz (with a phase noise of ≤−103dBc/Hz at 10 kHz offset from the carrier frequency). The OEO is subsequently used to drive an optical comb, generating 22 comb lines with a frequency spacing of 17.33 GHz covering a bandwidth of 360 GHz within a 20 dB envelope. By selecting two optical comb lines with a wavelength selective switch (WSS) and beating them in a uni-traveling carrier photodiode (UTC-PD), THz signals are generated at 101.5 GHz and 242.6 GHz with phase noise of -90 dBc/Hz and -78 dBc/Hz, respectively at 10 kHz offset from carrier frequency. Tunable mm-wave and THz signals can be generated either by changing the OEO oscillation frequency or the selected comb lines. Using the OEO driven OFCG, we implemented a RoF link at 242.6 GHz with a data rate of 24 Gbps over a wireless distance of 30 cm and with a bit error rate (BER) below the hard decision forward error correction (FEC) limit of 3.8×10−3 . This method allows the creation of an allphotonic frequency reconfigurable THz signal generator and RoF system

Self-oscillating Optical Frequency Comb: Application to Low Phase Noise mm-wave Generation and Radio-over-Fiber Link

A self-oscillating optical frequency comb generator (SOFCG) is demonstrated by applying the optoelectronic loop feedback to an optical frequency comb generator (OFCG) based on a dual-drive Mach–Zehnder modulator. The resulting SOFCG provides 23 comb lines with a frequency spacing of 11.84 GHz, corresponding to the oscillation frequency defined by the optoelectronic loop. The corresponding OFCG is also implemented by replacing the optoelectronic feedback loop with a microwave synthesizer at 11.84 GHz. A 94.8-GHz millimeter (mm)-wave signal is then generated by selecting two tones and heterodyning in a high-speed photodetector for both the SOFCG and the OFCG. The SOFCG system offers superior single sideband phase noise performance compared to the OFCG approach. Using the SOFCG developed here, it is possible to generate mm-wave signals up to 260 GHz, and this method is applicable to multiband radio-over-fiber (RoF) links. An RoF link is implemented with the SOFCG at 94.8 GHz. An LTE Advanced OFDM FDD 64-QAM signal of 20-MHz bandwidth is transmitted over a 1.3-m wireless distance

Optoelectronic recirculating delay line implementation of a high-q optoelectronic oscillator

A dual-loop optoelectronic oscillator incorporating an optoelectronic recirculating delay line in order to circumvent the limitations of optical coherence associated with all-optical loops is demonstrated. The optoelectronic oscillator produces a very stable signal at 5.4 GHz (suitable for WLAN 802.11n and 4G-WiMAX systems) with a sub-Hz 3-dB bandwidth and a Q-factor in excess of 1010. A phase noise of -115 dBc/Hz is recorded at 10 kHz offset, owing to the reduction in phase induced intensity noise, whilst side modes are significantly suppressed for offset values in the range 100 kHz - 1 MHz