Enhancement of multioctave dynamic range in a push-pull modulated analog photonic link

We demonstrate an analog photonic link with a high multioctave spurious-free dynamic range (SFDR) using a push-pull modulation technique of laser diodes combined with a balanced detection scheme. SFDR enhancements ranging from 5 dB to 18 dB, relative to the case of a single arm link, have been obtained in a frequency range of 2.5 GHz to 3.2 GHz

A Novel Modulation Scheme for Noise Reduction in Analog Fiber Optic Links

A novel balanced modulation and detection scheme for analog fiber optic links is proposed to overcome the limitations in signal-to-noise ratio (SNR) and dynamic range (DR). In this scheme, the modulating signal is split into positive and negative halves and applied to a pair of laser diodes. Both arms of the link will convey a half-wave rectified version of the signal. At the receiving end the signal is restored via differential detection. Calculation results show that significant improvement in link SNR together with suppression of second-order distortions are achieved

On chip frequency discriminator for microwave photonics signal processing

Microwave photonics (MWP) techniques for the generation, distribution and pro- cessing of radio frequency (RF) signals have enjoyed a surge of interest in the last few years. The workhorse behind these MWP functionalities is a high performance MWP link. Such a link needs to fulfill several criteria namely high link gain, low noise figure and high spuriousfree dynamic range (SFDR). High SFDR dictates high linearity and low noise in the links. In a conventional intensity modulated direct detection (IMDD) link the SFDR is mainly limited by the laser relative intensity noise (RIN) and the third order intermodulation distortion (IMD) either from the directly modulated laser or the electro-optic modulator

A novel microwave photonic link employing cascaded ring resonators as balanced optical discriminators

We report the design, fabrication and characterization of a balanced optical discriminator for a high performance phase modulation-direct detection microwave photonic link (MPL). The discriminator is an integrated optical filter consisting of five ring resonators which are fully tunable using thermo-optical tuning. The discriminator is configured to yield a desired transfer where the intensity transmission ramps linearly with the frequency. The performance of an MPL employing this discriminator is investigated. Measurement results on the MPL noise, linearity and spurious-free dynamic range are presented and discussed

A study of slow light in 1D photonic crystals

Slow light (SL) states corresponding to wavelength regions near the bandgap edge of grating structure are known to show strong field enhancement. Such states may be excited efficiently by well-optimised adiabatic transitions in such structures, e.g., by slowly turning on the modulation depth. To study adiabatic excitations, a detailed research in 1D is performed to obtain insight into the relation between the device parameters and properties like enhancement and modal reflection. The results enable the design of an adiabatic device for efficient excitation of SL states in 1D. In addition of that, the effects of small wavelength variations as well as that of small fluctuations in the modulation depth of the grating have been investigated

Development of a broadband and squint-free Ku-band phased array antenna system for airborne satellite communications

Novel avionic communication systems are required for various purposes, for example to increase the flight safety and operational integrity as well as to enhance the quality of service to passengers on board. To serve these purposes, a key technology that is essential to be developed is an antenna system that can provide broadband connectivity within aircraft cabins at an affordable price. Currently, in the European Commission (EC) 7th Framework Programme SANDRA project (SANDRA, 2011), a development of such an antenna system is being carried out. The system is an electronically-steered phased-array antenna (PAA) with a low aerodynamic profile. The reception of digital video broadcasting by satellite (DVB-S) signal which is in the frequency range of 10.7-12.75 GHz (Ku-band) is being considered. In order to ensure the quality of service provided to the passengers, the developed antenna should be able to receive the entire DVB-S band at once while complying with the requirements of the DVB-S system (Morello & Mignone, 2006). These requirements, as will be explained later, dictate a broadband antenna system where the beam is squint-free, i.e. no variation of beam pointing direction for all the frequencies in the desired band. Additionally, to track the satellite, the seamless tunability of the beam pointing direction of this antenna is also required. In this work, a concept of optical beamforming (Riza & Thompson, 1997) is implemented to provide a squint-free beam over the entire Ku-band for all the desired pointing directions. The optical beamformer itself consists of continuously tunable optical delay lines that enable seamless tunability of the beam pointing direction

Phased array antenna steering using a ring resonator-based optical beam forming network

A novel beam steering mechanism for a phased array antenna receiver system is introduced. The core of the system is a ring resonator-based integrated optical beam forming network chip. Its principles are explained and demonstrated by presenting some measurement results. The system architecture around the chip is based on a combination of frequency down conversion, filter-based optical single sideband modulation and balanced coherent detection. It is proven that such an architecture has significant advantages with respect to a straightforward architecture using double sideband modulation and direct detection, namely relaxed bandwidth requirements on the optical modulators and detectors, reduced complexity and optical losses of the beam forming chip, and enhanced dynamic range

Optical beam forming for phased-array antennas

The activities of the Telecommunication Engineering (TE) group span the communications spectrum from copper cables, optical fibres, microwaves, radio and electromagnetic compatibility. Our research concentrates on optical signal processing and networks, mobile communications, microwave techniques and radiation from ICs and PCBs [1]. A considerable (and particularly interesting) part of it is related to optical beam forming for phased array antennas, using optical ring resonators.\ud In this article the theoretical basics and practical challenges of this interesting research topic will be summarized.\u

Optical phase synchronization in coherent optical beamformers for phased array receive antennas

An optical phase synchronization system using a power feedback loop technique is experimentally demonstrated. The system allows coherent combining of signals modulated on the same optical carrier in a hybrid optical beam forming system setup