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A new technique to implement a nonuniformly-spaced photonic microwave delay-line filter using a spatially discrete chirped fiber Bragg grating (SD-CFBG) is proposed and investigated. It is different from a regular nonuniformly-spaced photonic microwave delay-line filter where a laser array with nonuniformly spaced wavelengths is used to provide nonuniformly-spaced filter taps, the proposed method...
Horizontal Cu/SiO2/Si/SiO2/Cu nanoplasmonic slot waveguides are experimentally demonstrated using the standard Si CMOS technology, which exhibit attractive properties of deep subwavelength confinement, relatively low propagation loss, and effective coupling with the conventional Si wire waveguide. Based on this high-performance nanoplasmonic slot waveguide, various nanoplasmonic passive components...
An overview of microwave photonics research for defense applications in Singapore is given. Several examples of ongoing work in this area by the Singaporean academia will also be discussed.
Nonlinearities in the RF output of a p-i-n photodiode are attributed to photocurrent-dependent changes in the photodiode quantum efficiency (responsivity). Physical causes of the current dependence are discussed, and a mathematical model for calculating the resulting distortion power is presented. Photodiode responsivity is measured and used to calculate distortion, which is then compared to measured...
This paper presents a novel multiplexing technique of wireless signals of the same frequency band, such as multiple-input-multiple-output (MIMO) signal, on a single optical carrier. In proposed multiplexing technique the use of chromatic dispersion controllers is a key to the suppression of signal interferences. In general RoF system, received wireless signal intensity is periodically varied depending...
A photonic approach with multiple free spectral ranges (FSRs) is proposed to perform instantaneous frequency measurement. In the proposed approach, multiple channels are firstly designed with the use of multiple laser sources operating at different wavelengths and a comb filter, leading to the generation of multiple FSRs at these channels. The microwave signal with its frequency to be measured is...
We present a simple accurate method for the evaluation of the half-wave voltage of phase modulators at high frequency that does not require any high-speed photodiode or components or spectral analyzer. It is based on the use of a tunable unbalanced interferometer and optical mean power measurement. We report on results obtains with large bandwidth lithium niobate phase modulators.
We have proposed a fiber-optic spectrum shaper that can generate optical spectrum with variable shapes. The simulation results verified the diversity of the output optical spectrum and the experimental results are shown to demonstrate the effectiveness of this spectrum shaper.
Improvements in optical component specifications have moved broadband airborne optical link technology into an early adoption phase. This paper will describe the design of an airborne optical link and present challenges observed over the design cycle.
A full tunable microwave photonic phase shifter involving a single semiconductor optical amplifier (SOA) is proposed and demonstrated. It is shown that the optical filtering phase characteristic can be advantageously employed to switch between slow and fast light regimes. 360° phase shift has been achieved using two different optical powers at the SOA input by properly adjusting the frequency detuning...
A simplified uplink communication scheme for millimeter-wave (mm-wave) radio-over-fiber system employing RF self-homodyning at the base station (BS) is proposed and experimentally demonstrated. The proposed scheme establishes a simple low-speed data transmission from the BS to the central station and simplifies the BS and uplink optical transport by removing most of the required high speed optoelectronic...
We report on measured optical fiber W-band wireless channel characteristics such as frequency response, channel loss and fading, directivity, channel capacity and phase noise. Our proposed system performs a sextuple frequency up-conversion after 20 km of fiber transmission, followed by a W-band wireless link. Our experimental measurements are intended to provide engineering rules for designing hybrid...
We report on a 4-channel radio-frequency arbitrary waveform generator, capable to switch within a clock period among synthesized radio-frequency arbitrary waveforms. The system works by combining an original switching scheme of time-multiplexed multi-wavelength optical frequency combs with a two-dimensional line-by-line pulse shaper featuring broad bandwidth operation over large temporal windows....
In this paper we discuss about the extended reach 10-Gbit/s Passive Optical Network (XGPON) and the use of a Saturated Collision Amplifier (SCA) for the up- and downstream extension. Especially the upstream amplification is challenging because of the used (i.e. standardized) wavelength and the bursty nature of the traffic. In order to benefit the SCA scheme, the Optical Network Units (ONUs) have to...
In this paper, we show analytically for the first time that the complementary phase properties of a polarization modulator can be utilized to cancel the dispersion-induced second-order distortions in a Time-Stretched Analog-to-Digital Converter (TSADC). Using differential operation and digital post- processing in the form of arcsine operation, this enables the suppression of system nonlinearities-induced...
Nowadays, the RoF technology can be utilized to converge the heterogeneous broadband wireless communications, because of their huge bandwidth and protocol transparency. Transmitting RF signals are deteriorated by the nonlinearity of the RoF link. This paper provides theoretical estimation of intermodulation distortion of heterogeneous OFDM service including IEEE802.11g and IEEE802.16e-2005 over subcarrier...
A Tunable optoelectronic oscillator (OEO) implemented employing a high-Q spectrum sliced photonic microwave transversal filter without using any electronic microwave filters is proposed and experimentally demonstrated for the first time to our knowledge. The high-Q photonic microwave transversal filter is implemented using a sliced broadband optical source and a dispersive element, to perform frequency-tunable...
We experimentally evaluate the performance of slow light microwave photonic phase shifters based on cascaded SOAs in the context of several figures of merit. Attention is focused on the assessment of the RF net gain, noise figure and nonlinear distortion. Finally, recommendations on the performance optimization of this sort of approaches are detailed.
The concept of high capacity RF-assisted optical transmission system is described. Design parameters and performance trade-offs are analyzed using simulations and the performance of a 112 Gbit/s dual sub-channel system experimental demonstrator is reported. Successful optical transmission up to 824 km is reported.
We demonstrated the dependence of IR-UWB signal waveform on the RZ pulse width, and made it clear that optical RZ pulse width of 12.5 to 90 ps is necessary in combined 1.25 Gbps 10 km SMF and wireless link with UWB band of 7.25–10.25GHz. The 10Gbps (1.25 Gbps × 8TDM) IR signal transmission in optical fiber link is also demonstrated using 29 ps optical pulse. The system satisfies the communication...
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