Manuel Rius

Integrable high order UWB pulse photonic generator based on cross phase modulation in a SOA-MZI

We propose and experimentally demonstrate a potentially integrable optical scheme to generate high order UWB pulses. The technique is based on exploiting the cross phase modulation generated in an InGaAsP Mach-Zehnder interferometer containing integrated semiconductor optical amplifiers, and is also adaptable to different pulse modulation formats through an optical processing unit which allows to control of the amplitude, polarity and time delay of the generated taps.

Multiband-UWB Signals Generation Based on Incoherent Microwave Photonic Filters

A structure for multiband-UWB waveforms generation is proposed using an N tap microwave photonic filter with positive and negative taps. The system is based on phase inversion in electro-optical modulators and the sliced broadband source optical signal by means of a structure of AWGs, which permits us to obtain a high number of taps. System performance is experimentally shown by the generation of a uniform waveform. Capabilities as reconfigurability and frequency tuning have been also experimentally demonstrated. The flexibility of the system allows us to obtain multiband UWB waveforms, which fulfill the FCC spectral requirements.

Scalable UWB photonic generator based on the combination of doublet pulses

We propose and experimentally demonstrate a scalable and reconfigurable optical scheme to generate high order UWB pulses. Firstly, various ultra wideband doublets are created through a process of phase-to-intensity conversion by means of a phase modulation and a dispersive media. In a second stage, doublets are combined in an optical processing unit that allows the reconfiguration of UWB high order pulses. Experimental results both in time and frequency domains are presented showing good performance related to the fractional bandwidth and spectral efficiency parameters.

Harmonic distortion in microwave photonic filters

We present a theoretical and experimental analysis of nonlinear microwave photonic filters. Far from the conventional condition of low modulation index commonly used to neglect high-order terms, we have analyzed the harmonic distortion involved in microwave photonic structures with periodic and non-periodic frequency responses. We show that it is possible to design microwave photonic filters with reduced harmonic distortion and high linearity even under large signal operation.

Chirped Waveform Generation With Envelope Reconfigurability for Pulse Compression Radar

Chirped pulses generation is evaluated and experimentally demonstrated by means of the processing of incoherent optical signals using a nonlinear dispersive element. The capability of generating chirped electrical pulses, in which the instantaneous frequency changes with time, has been demonstrated for a Gaussian waveform envelope similar to photonic coherent techniques. For pulse compression radar systems, the control of the pulse envelope permits to increase the coverage distance of the transmitted signals and the spatial resolution of the system. In this sense, the envelope control of the generated waveform has been also experimentally demonstrated for different profiles, such as gradual, hyperbolic tangent, and uniform by means of the optical signal power spectral density. Indeed, we have experimentally probed how the resolution and the coverage distance of the signals can be increased for a uniform waveform in a pulse compression radar system.

Experimental photonic generation of chirped pulses using nonlinear dispersion-based incoherent processing

We experimentally demonstrate, for the first time, a chirped microwave pulses generator based on the processing of an incoherent optical signal by means of a nonlinear dispersive element. Different capabilities have been demonstrated such as the control of the time-bandwidth product and the frequency tuning increasing the flexibility of the generated waveform compared to coherent techniques. Moreover, the use of differential detection improves considerably the limitation over the signal-to-noise ratio related to incoherent processing.

Optical single sideband transmitter using phase modulation and a photonic integrated filter

We propose and experimentally demonstrate the operation of a linear OSSB+C transmitter based on combining a phase modulator and an integrated band-pass filter. The transmitter can provide several advantages including broadband operation, modulation linearity, stability and improved RF modulation efficiency.

Incoherent Photonic Processing for Chirped Microwave Pulse Generation

We propose and experimentally demonstrate a fully reconfigurable generator of chirped microwave pulses based on the processing of an incoherent optical signal by means of a dispersive element with a non-uniform optical spectral shaping. The system performance has been proven by the generation of different chirped microwave pulses. Different capabilities of the system have been experimentally demonstrated as frequency tunability and time-bandwidth product control by means of the dispersive element and optical source power distribution. Furthermore, the possibility for generating chirped microwave pulses with positive and negative chirp characteristic has been shown achieving similar chirps in terms of magnitude but opposite sign. For it, the chirp characteristic is introduced by proper shaping of the optical source signal power distribution.

Analysis of harmonic distortion involved in microwave photonic filters

We present a theoretical and experimental analysis of nonlinear microwave photonic filters. Far from the conventional condition of low modulation index to neglect high-order terms, we analyze the harmonic distortion involved in microwave photonic structures to profit the filtering properties. We demonstrate that it is possible to design microwave photonic filter to reduce the harmonic distortion by achieving a high linearity in the system performance under large signal operation.

High-Order UWB Pulses Generation Adaptable to Bi-Phase Modulation

In this letter, we present a high-order impulse-radio ultra-wideband (UWB) pulses generator based on the processing of incoherent optical signals by a dispersive element. The full waveform reconfigurability is achieved by the control of the optical signal power spectral density profile. Operation principle is experimentally shown by the generation of classical UWB pulses: monocycle and doublet. High-order UWB pulses generation is experimentally demonstrated by the generation of triplet and quadruplet. Also, the proper adjustment of the optical signal power distribution permits to reduce the baseband content of the synthesized waveform, which is critical in UWB environments to achieve spectrally efficient solutions. Moreover, system flexibility allows the adaptation to a bi-phase modulation scheme. This feature has been proved by the generation of the inverted version of the UWB pulses achieved in this letter.