External Light Wave Research Articles

Silicon Photonic Integrated Optoelectronic Oscillator for Frequency-Tunable Microwave Generation

Photonic generation of a frequency-tunable microwave signal based on a silicon photonic integrated optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The silicon photonic chip includes a high-speed phase modulator (PM), a thermally tunable micro-disk resonator (MDR), and a high-speed photodetector (PD). When an external light wave is injected into the chip, by a joint use of the PM, the MDR, and the PD, a bandpass microwave photonic filter (MPF) based on phase modulation and phase-modulation to intensity-modulation (PM-IM) conversion is realized. If the output microwave signal from the MPF is fed to the microwave input port of the PM with a sufficiently large gain provided by an electrical amplifier, the MPF becomes an OEO. By controlling the electrical power applied to a micro-heater, the resonance frequency of the MDR is tuned, which leads to the tuning of the MPF, and thus, the OEO oscillation frequency. In the experimental demonstration, two silicon photonic integrated OEOs using two MDRs with different micro-heaters are studied. The first OEO has a high-resistivity metallic micro-heater placed on top of the MDR, and the second OEO has a p-type doped silicon heater in the MDR. The two thermally tunable MDRs are characterized, and the performance of the MPFs based on the two MDRs is evaluated. The use of the two MPFs to implement two OEOs is performed, and their performance is evaluated in terms of frequency tunable range, phase noise, and power consumption.

Extremely high-intensity laser interactions with fundamental quantum systems

The field of laser-matter interaction traditionally deals with the response of atoms, molecules, and plasmas to an external light wave. However, the recent sustained technological progress is opening up the possibility of employing intense laser radiation to trigger or substantially influence physical processes beyond atomic-physics energy scales. Available optical laser intensities exceeding ${10}^{22}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$ can push the fundamental light-electron interaction to the extreme limit where radiation-reaction effects dominate the electron dynamics, can shed light on the structure of the quantum vacuum, and can trigger the creation of particles such as electrons, muons, and pions and their corresponding antiparticles. Also, novel sources of intense coherent high-energy photons and laser-based particle colliders can pave the way to nuclear quantum optics and may even allow for the potential discovery of new particles beyond the standard model. These are the main topics of this article, which is devoted to a review of recent investigations on high-energy processes within the realm of relativistic quantum dynamics, quantum electrodynamics, and nuclear and particle physics, occurring in extremely intense laser fields.

Simple theoretical analysis of the photoemission from quantum confined effective mass superlattices of optoelectronic materials

The photoemission from quantum wires and dots of effective mass superlattices of optoelectronic materials was investigated on the basis of newly formulated electron energy spectra, in the presence of external light waves, which controls the transport properties of ultra-small electronic devices under intense radiation. The effect of magnetic quantization on the photoemission from the aforementioned superlattices, together with quantum well superlattices under magnetic quantization, has also been investigated in this regard. It appears, taking HgTe/Hg1−xCdxTe and InxGa1−xAs/InP effective mass superlattices, that the photoemission from these quantized structures is enhanced with increasing photon energy in quantized steps and shows oscillatory dependences with the increasing carrier concentration. In addition, the photoemission decreases with increasing light intensity and wavelength as well as with increasing thickness exhibiting oscillatory spikes. The strong dependence of the photoemission on the light intensity reflects the direct signature of light waves on the carrier energy spectra. The content of this paper finds six different applications in the fields of low dimensional systems in general.

Influence of External Light Waves on the Thermoelectric Power Under Strong Magnetic Field in Ultrathin Films, Quantum Wires and Quantum Dots of Optoelectronic Materials

In this paper, an attempt is made to study the influence of external light waves on the thermoelectric power under strong magnetic field (TPSM) in ultrathin films (UFs), quantum wires (QWs) and quantum dots (QDs) of optoelectronic materials whose unperturbed dispersion relation of the conduction electrons are defined by three and two band models of Kane together with parabolic energy bands on the basis of newly formulated electron dispersion laws in each case. We have plotted the TPSM as functions of film thickness, electron concentration, light intensity and wavelength for UFs, QWs and ODs of InSb, GaAs, Hg1-xCdxTe and In1-xGaxAsyP1-y respectively. It appears from the figures that for UFs, the TPSM increases with increasing thickness in quantum steps, decreases with increasing electron degeneracy exhibiting entirely different types of oscillations and changes with both light intensity and wavelength and these two latter types of plots are the direct signature of light waves on opto-TPSM. For QWs, the opto-TPSM exhibits rectangular oscillations with increasing thickness and shows enhanced spiky oscillations with electron concentration per unit length. For QDs, the opto-TPSM increases with increasing film thickness exhibiting trapezoidal variations which occurs during quantum jumps and the length and breadth of the trapezoids are totally dependent on energy band constants. Under the condition of non-degeneracy, the results of opto-TPSM gets simplified into the well-known form of classical TPSM equation which the function of three constants only and being invariant of the signature of band structure.

Polarization-sensitive optical phenomena in thick semiconducting nanowires

For semiconducting nanowires with the dielectric constant ε differing from that of their environment, the distribution of ac electric fields, created in a nanowire by an external lightwave and emitted outside by an effective dipole in a nanowire, is found. The results are used for calculating the spectra and polarization properties of optical absorption, luminescence, and photoconductivity in such nanowires. For relatively thick nanowires, with diameter a comparable to the light wavelength, all polarization characteristics exhibit strong oscillations with the light frequency ω and even change the sign over some intervals of ωa∕c. Some of these phenomena have already been observed experimentally. In a system of randomly oriented nanowires, they result in a polarization memory where polarization of photoluminescence is determined by the polarization of the exciting light, by a factor strongly dependent on the frequencies of both the exciting and emitted light.

Fast Wavelength Switching Based on a Fabry-Perot Laser Pair Using Optical Injection

We propose and experimentally demonstrate a new fast wavelength-selectable laser technique, which is based on Fabry–Perot (FP) lasers with external light wave injection. By using different bias currents of FP lasers, wavelength tuning can be realized. In the experiment, the tuning of three different wavelengths tuning, the side-mode suppression ratio of >20 dB, and the wavelength switching time of <2 ns were attained.

Fast tunable laser based on Fabry-Perot lasers with optical injection

We have proposed and experimentally demonstrated a new tunable laser structure, which is based on Fabry-Perot (FP) lasers with external lightwave injection. The wavelength tuning can be obtained by adjusting the bias currents of FP lasers. The wavelength tuning time of 19 dB have been achieved experimentally. In addition, the SMSR performance has also been investigated. This tunable laser has the advantage of simple architecture, potentially low cost, data direct modulation, and fast wavelength tuning, and is expected to benefit the applications of fast wavelength tuning.

Linear nonstationary optical dimensional resonances in atomic nanostructures

The existence of linear nonstationary optical resonances in a diatomic nanostructural object with a dipole-dipole atomic interaction has been proved. A new solution to the joint system of modified Bloch optical equations and nonlocal field equations is obtained for time intervals much shorter than the times of phase and energy relaxation. Formulas for effective polarizabilities of the object’s atoms, which have a set of dimensional resonances, are derived. The frequencies of these resonances significantly differ from the eigenfrequencies of the object’s atoms, and their properties depend on the interatomic distance, light-pulse duration, initial atomic inversions, and the orientation of the object’s axis relative to the direction of incidence of the external light wave.

Optical holography of diatomic small nanostructure objects and the near-field effect: Dimensional resonances at normal incidence of external optical radiation on a small object

The interaction of an atomic group occupying a volume with linear dimensions which are considerably smaller than the length of an external light wave is considered. On the basis of the joint set of equations for the electric field strength of the light wave and the optical equations for linear dipole oscillators, the self-consistent problem of determination of the field at the points of location of the atoms, as well as at different points of observation outside the atomic group (a small object) in the wave and near-field zones, is solved. An optical plane hologram of a small object is obtained by way of interference of the coherent field of dipoles of the object and a reference coherent wave in a certain plane of observation points far from the object in the wave zone. It is shown with the help of numerical experiments that a small object forms interference fringes with a good contrast, which allows one to use optical quasi-resonant emission for the development of a nondestructive method of investigation of small objects.

Near-field effect in optics of small objects composed of dipole atoms

A self-consistent problem of interaction of two dipole atoms separated by an unrestricted distance with the field of a quasi-resonance light wave was solved on the assumption that the investigated atoms are Lorentz linear oscillators and the polarizing fields inside the system consist of the Coulomb and the retarded parts. The solution obtained was investigated for the case where the atoms have the same polarizability and the distance between them is much smaller than the length of the external light wave. Formulas for the electric fields inside a small object and outside it have been obtained. It is shown that inside a small two-atom object there can take place longitudinal and transverse optical vibrations accompanied by corresponding dispersion effects depending on the interatomic distance and the angle between the axis of the system and the direction of propagation of the external light wave. The field outside the small object in the wave zone is linearly polarized when the external wave has linear polarization. However, the direction of polarization of the corresponding waves is largely determined by their frequency. It is also shown that the amplitude of the field outside the small object in the wave zone depends greatly on the frequency of the external field and the interatomic distance. The effects observed are considered as a near-field effect in optics of small objects. This phenomena makes it possible to investigate the structure of small objects with the use of optical radiation.

The near-field effect in a quantum computer

It is shown that in principle it is possible to write optical information on individual quasiresonant atoms in a concentrated system by changing the angle of incidence of an external light wave.

Chaotic motion of the density operator for an exciton-photon system

A semiconductor inside a ring cavity is driven by an external light wave. Free carriers screen the interaction between excitons and photons. The density operator of this dissipative system is represented by a quasi-distribution assumed to be in the form of a generalized Gaussian. Its coefficients obey a system of 15 ODEs. There are chaotic solutions for the density operator and for the expectation values of some observables too. Nonclassical states of the boson modes may appear even during the chaotic motion.