José Capmany

Reconfigurable fiber-optic delay line filters incorporating electrooptic and electroabsorption modulators

The authors propose and demonstrate experimentally a novel class of flexible and fastly reconfigurable fiber optic delay line filters for microwave signal processing that incorporate electrooptic and electroabsorption modulators as weighting elements.

Solutions to the synthesis problem of optical delay line filters.

We report new design methods for the synthesis of incoherent low-pass fiber-optic delay line filters with finite impulse responses. These structures are considerably simpler in their operation than infinite impulse response filters, are always stable, and are capable of performing almost the same signal-processing operations. Some of their implementations and applications as adaptive filters or for demultiplexing of high-definition television signals are presented and discussed.

Experimental Demonstration of 360 o Tunable RF Phase Shift Using Slow and Fast Light Effects

A microwave photonic phase shifter realizing 360ophase shift over a bandwidth of more than 10GHz is demonstrated using optical filtering assisted slow and fast light effects in a cascaded structure of semiconductor optical amplifiers

Wavelength conversion of SCM signals using semiconductor optical amplifiers: theory, experiments, and applications

In this paper, we deal with the subject of cross-gain modulation (XGM) and cross-phase modulation (XPM) semiconductor optical amplifier-based wavelength conversion of optical channels carrying subcarrier multiplexing signals in a comprehensive way. The equations and models that describe the conversion process and the resulting harmonic and intermodulation distortions are obtained showing the superior performance of XPM over XGM in terms of secondand third-order distortion and contrast ratio. Experimental results for XGM-based wavelength conversion that confirm the results predicted by our theoretical models are presented, and finally, we consider the specific application of wavelength conversion of optical channels carrying full frequency plans such as that of cable television applications.

Highly Chirped Reconfigurable Microwave Photonic Filter

A photonic structure is proposed to implement a chirped single-bandpass filter based on a broadband optical source, an inteferometric structure, and a nonlinear dispersive element. The ability of controlling a quasi-linear chirp in the passband by using the dispersive element in addition to the possibility of tuning and reconfiguring the passband by means of a proper configuration of the interferometric structure and the optical source are special and unique features of the system proposed. Moreover, the flexibility of the proposed filter permits us to achieve an operation range up to tens of gigahertz improving the chirp achieved by current proposals in one order of magnitude.

UWB Monocycle Generator Based on the Non-Linear Effects of an SOA-Integrated Structure

In this letter, we propose and experimentally demonstrate a novel and single structure to generate ultra-wideband (UWB) pulses by means of the cross-phase modulation present in a semiconductor optical amplifier unified structure. The key components of this system is an integrated Mach-Zehnder interferometer with two semiconductor optical amplifiers and an optical processing unit. The fusion of these two components permits the generation and customization of UWB monocycle pulses. The polarity of the output pulses is easily modified through the single selection of a specific input port. Moreover, the capacity of transmitting several data sequences is demonstrated and the potentiality to adapt the system to different modulation formats is analyzed.

Experimental demonstration of the continuous tuning of microwave photonic filters by sinusoidal modulation of the filter coefficients

We show the results of a technique to tune continuously the resonances of the microwave photonic filters are shifted by changing the weight of the optical taps. It improves the performance of the cited filters.

Reconfigurable integrated waveguide meshes for photonic signal processing and emerging applications

We review the recent advances reported in the field of integrated photonic waveguide meshes, both from the theoretical as well as from the experimental point of view. We show how these devices can be programmed to implement both traditional signal processing structures, such as finite and infinite impulse response filters, delay lines, beamforming networks as well as more advanced linear matrix optics functionalities. Experimental results reported both in Silicon and Silicon Nitride material platforms will be presented. We will also discuss the main programming algorithms to implement these structures and discuss their applications either as standalone systems or as part of more elaborated subsystems in microwave photonics, quantum information and machine learning.

Amplification of the transmission rate for quantum key distribution based on subcarrier multiplexing

The security represents one of the most important perspective future lines in telecommunications. This work is focused on new techniques and methods employing the properties of quantum physics to provide the ability to obtain an unconditional security. This article proposes the use of cryptographic hash functions used in the amplification layer of privacy to expand the bit rate relying on the properties of these functions. In this way, our approach permits to improve the quantum key transmission rate when optically is limited. We demonstrate the potentiality of the proposal with an amplification of 6 dB.

Noise Figure of Slow Light Cascaded SOA based Microwave Photonic Phase Shifters

The noise figure of Slow and Fast Light Microwave Photonic phase shifters made up by SOA followed by optical filtering stages is experimentally evaluated. Noise figure results show compression when adding the third cascaded stage.