Frequency conversion using highly non-degenerate four-wave mixing is reported in InAs/GaAs quantum-dot Fabry- Perot lasers. In order to compress the spontaneous emission noise, the laser is optically injection-locked. Under proper injection conditions, the beating between the injected light frequency and the cavity resonant frequency dominates the dynamic behavior and enhances a carrier modulation resonance at frequencies higher than the relaxation oscillation frequency. Conversion efficiencies as high as -12 dB associated to a large optical signal-to-noise ratio of 36 dB are reported. The conversion bandwidth is extended up to 2.1 THz for down-conversion (resp. 3.2 THz for up-conversion) with a quasi-symmetrical response between up- and down-converted signals.
In this work, the sensitivity to external optical feedback of two different InAs/GaAs QD Fabry-Perot (FP) lasers is investigated under long cavity regime. The first, which has a 1.5 mm-long cavity, emits on the GS while the second one, which is 1 mm long, radiates solely on the ES transition. The results indicate that for the same bias level, the ES laser presents a larger sensitivity to external feedback, the critical level being under 1% versus above 9% for the GS laser. In particular, the ES laser exhibits a route to chaos such that the first destabilization occurs for a lower feedback strength than for the GS laser.
This paper presents a new double-frequency method for the instantaneous frequency and amplitude measurement of
unknown microwave signal. Using the specific interaction of double-frequency radiation and FBG (fiber Bragg grating)
with a π phase shift allowed us to obtain measuring characteristics, that are independent of the energy fluctuations of the
optical carrier and the microwave signal, and reduce measurement inaccuracy caused by temperature instability of the
spectral characteristics of used elements.
The aim of this paper is to examine the refractometric method of determining the octane number of gasoline and the
presence of organic compounds in biological fuels. A feature of this method is π-shifted etched fiber Bragg grating as
the sensing element utilization, which is characterized by a narrow bandwidth. The advantage of this method is the
detection of changes in the refractive index at the level of 1,3×10-5.
The paper considers possibility of using a system based on amplitude measurement method with a fiber Bragg grating as
a sensitive element. The features of measurement technique is application of Bragg gratings with a special spectrum
structure for different industries.
Optical microelectromechanical systems (MEMS) technology or micro-optoelectromechanical systems (MOEMS)
technology has experienced rapid growth in recent years and find its application in modern telecommunications,
including fiber optics. This technology can provide high-performance features and new functionalities for optical and
communication systems. Therefore due to their widespread applications, MEMS variable optical attenuators (VOA) have
been one of the most attractive fiber optic components.
We analyze the most effective way to obtain microwave-photonic filter's coefficients, specifically implemented by electro-
optical modulators. These devices are attractive to obtain desired number and sign of coefficients which results in
high tunability and reconfigurability of filters. One have to decide which device will be the most appropriate in obtaining
desired frequency response of the filter. The results of numerical simulations are presented for phase modulator, singleport
mach-zehnder modulator and dual-port mach-zehnder modulator.
All-optical microwave filter has been a topic of interest for over two decades because of the many advantageous features
such as large time-bandwidth product, wide tunability, high Q-factor, low loss, light weight, and immunity to electromagnetic
interference offered by photonic devices. All-optical microwave photonic filter is a system used to implement
microwave filtering in the optical domain, which can provide a large tunability and a high Q factor which are usually
difficult to realize through conventional electronic methods. In addition, since the microwave signal is processed directly
in the optical domain without additional optical-electrical and electrical-optical conversions, the photonic microwave
filters are particularly suitable for applications such as optically controlled phased-array antennas, radio-over-fiber (RoF)
systems, and other microwave-photonic links (MPLs). For these reasons, photonic microwave filters have attracted considerable
interest for a few years.
We demonstrate optical comb generator based on dual drive Mach-Zehnder modulator with tunable output spectrum and
its application in ROF filters. Mathematically it has been shown how to obtain comb spectrum with adjusted number of
harmonics with desired amplitudes and necessary wavelength separation. The results of numerical simulations are presented.
Paper investigates various optical link simulation programs that can be used in different teaching courses. Web-based
educational materials became popular because these resources can be accessed by anyone who has access to the World
Wide Web. In this paper, we will review software that deals with the simulation of optical communication systems. The
main advantages of embedding this kind of software into teaching courses consist of opportunity to experiment and to
research by using simulation. Students can experiment with different facts and test the system which may otherwise
require a large and an expensive setup of laboratory equipment and at the same time making the theoretical courses more
interesting to learn.
A method and device for all-optical bandpass and comb microwave filter synthesis is presented. Negative coefficients that are necessary to obtain bandpass filter are provided through a proposed method applied to a electro-optical modulator.
High level of optical radiation in optical fiber due to utilization of optical amplifiers causes an interaction of strong electromagnetic field with fiber core material. As a result of this interaction different nonlinear effects in optical fiber may occur. In this paper FWM effect is investigated. Methods that can be used to reduce deteriorations caused by this type of nonlinear interaction between optical signals and fiber core material are researched. Suggested FWM reducing system is presented.