Dark Pulses Research Articles

Bright–Dark Pulse Pair in a Figure-Eight Dispersion-Managed Passively Mode-Locked Fiber Laser

We report on the generation of bright–dark pulse pair in a figure-eight dispersion-managed (DM) passively mode-locked fiber laser with net anomalous cavity group velocity dispersion (GVD). The nonlinear amplifying loop mirror (NALM) is employed in this configuration to allow for passively mode-locked operation. Through carefully adjusting the polarization controllers (PCs), the bright–dark pulse pair could be easily achieved. Furthermore, it is found experimentally that the pulse pair is formed due to the cross coupling between the bright and dark pulses, which are located at two different wavebands.

A Study of Dynamic Optical Tweezers Generation for Communication Networks

We propose a novel system of the dynamic optical tweezers generated by a dark soliton in the fiber optic loop. A dark soliton known as an optical tweezer is amplified and tuned within the microring resonator (MRR) system. The required tunable tweezers with different widths and powers can be controlled. The analysis of dark-bright soliton conversion using a dark soliton pulse propagating within a MRR is analyzed. The control dark soliton is input into the system via the add port of the add/drop filter. The dynamic behavior of the dark-bright soliton conversion is observed. The required stable signal is obtained via a drop and throughput ports of the add/drop filter with some suitable parameters. In application, generation of optical tweezers and transportation can be realized by using the proposed system, where the communication network is performed. KEYWORD: Dynamic Optical tweezers, MRR, Add/drop filter, communication network

Acute Behavioral Responses to Light and Darkness in Nocturnal Mus musculus and Diurnal Arvicanthis niloticus

The term masking refers to immediate responses to stimuli that override the influence of the circadian timekeeping system on behavior and physiology. Masking by light and darkness plays an important role in shaping an organism's daily pattern of activity. Nocturnal animals generally become more active in response to darkness (positive masking) and less active in response to light (negative masking), and diurnal animals generally have opposite patterns of response. These responses can vary as a function of light intensity as well as time of day. Few studies have directly compared masking in diurnal and nocturnal species, and none have compared rhythms in masking behavior of diurnal and nocturnal species. Here, we assessed masking in nocturnal mice (Mus musculus) and diurnal grass rats (Arvicanthis niloticus). In the first experiment, animals were housed in a 12:12 light-dark (LD) cycle, with dark or light pulses presented at 6 Zeitgeber times (ZTs; with ZT0 = lights on). Light pulses during the dark phase produced negative masking in nocturnal mice but only at ZT14, whereas light pulses resulted in positive masking in diurnal grass rats across the dark phase. In both species, dark pulses had no effect on behavior. In the 2nd experiment, animals were kept in constant darkness or constant light and were presented with light or dark pulses, respectively, at 6 circadian times (CTs). CT0 corresponded to ZT0 of the preceding LD cycle. Rhythms in masking responses to light differed between species; responses were evident at all CTs in grass rats but only at CT14 in mice. Responses to darkness were observed only in mice, in which there was a significant increase in activity at CT 22. In the 3rd experiment, animals were kept on a 3.5:3.5-h LD cycle. Surprisingly, masking was evident only in grass rats. In mice, levels of activity during the light and dark phases of the 7-h cycle did not differ, even though the same animals had responded to discrete photic stimuli in the first 2 experiments. The results of the 3 experiments are discussed in terms of their methodological implications and for the insight they offer into the mechanisms and evolution of diurnality.

Human phase response curve to a 1 h pulse of bright white light

The phase resetting response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase response curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (∼8000 lux) and to compare this PRC to a <3 lux dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a <15 lux dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n=18) or <3 lux dim background light (n=18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (<3 lux) before and after the light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the <3 lux dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ∼40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration–response function for the effects of light on circadian resetting.

Simulation Of Soliton Amplification In Micro Ring Resonator For Optical Communication

A system consisting of a series of micro ring resonator (MRR) is proposed. Optical dark and bright soliton pulses propagating through the nonlinear waveguides are amplified. This system can be used in long distance communication system. The dark and bright soliton is input into the designed system. The nonlinear effect contributes to segregation of continuous soliton pulse into smaller pulses. In this way large bandwidth of optical signals can be obtained. The power amplification occurs when the soliton propagates along the MRRs systems. In this research the concern is the generation of amplified pulse of optical dark and bright soliton while propagating in the MRR device. Simulated results show the amplification of bright soliton in which the input power increases from 0.6 W to 10.9331 W and 7.684 W at the trapped wavelength of 1520.428 nm and 1519.912 nm respectively. Key words: Optical soliton; dark soliton; bright soliton; soliton amplification

Determination Of Fwhm For Solition Trapping

In this study an interesting system in which a bright and dark soliton pulse can be stopped inside a nonlinear waveguide is presented. Here, we propose a system consisting of a series of ring resonators for optical trapping within a nonlinear waveguide. The bright and dark solitons can be controlled and slowed down within the waveguide. The FWHM for the output signals are calculated and used as an optical memory. Bright and dark soliton behaviors within a micro and nano ring resonator are also investigated and described. The required pulse is filtered and amplified, can be controlled and localized within the system. The localized bright and dark solitons are stopped by controlling the input power, which means that the photon stopping can be controlled by light in a ring resonator. Key words: Dark soliton; bright soliton; nonlinear nano waveguide; stopped light

All-optical logic AND and OR gates generated by dark–bright soliton conversion

In this paper, a novel system of simultaneous optical logic AND and OR gates using dark–bright soliton conversion within the add/drop optical filter system is proposed. By using the dark–bright soliton conversion concept, the switching output signal response time of ns can be obtained. The input logic <!-- no-mfc -->‘0’<!-- /no-mfc --> and control logic <!-- no-mfc -->‘0’<!-- /no-mfc --> are formed by using the dark soliton pulse (D) trains. We found that the simultaneous optical logic AND and OR gates at the drop and through ports can be formed, respectively. The comparison data of the commercial system is also given, which is shown that the proposed system has the advantage over the commercial ones.

Soliton spin manipulation using an optical add-drop filter

By using the optical add-drop filter which is formed by a microring resonator.After a dark soliton pulse is fed into an input port of the add-drop filter, the orthogonal soliton pair (dark and bright solitons) can be formed within the system and detected simultaneously at the output ports. Under the resonant condition, the conversion of dark and bright solitons corresponding to the left-hand and right hand soliton orientations can be generated and seen. Whenever a soliton(photon) is absorbed by an object, an angular momentum of either +h or −h is imparted to the object, in which two possible soliton states known as soliton spins are exhibited and confirmed by the helical phase presentation. In application, the train of orthogonal solitons, that is, many solitons (photons) with slightly different wavelengths can be generated by using the modified add-drop filter, which is available for many soliton spin investigations. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1100–1103, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26671

Spatiotemporal Dispersion and Wave Envelopes with Relativistic and Pseudorelativistic Characteristics

A generic nonparaxial model for pulse envelopes is presented. Classic Schrödinger-type descriptions of wave propagation have their origins in slowly-varying envelopes combined with a Galilean boost to the local time frame. By abandoning these two simplifications, a picture of pulse evolution emerges in which frame-of-reference considerations and space-time transformations take center stage. A wide range of effects, analogous to those in special relativity, then follows for both linear and nonlinear systems. Explicit demonstration is presented through exact bright and dark soliton pulse solutions.

Optical Soliton Spin Manipulation Based-on AlGaAs/GaAs Microring Resonator

In this paper, we present the optical soliton spin manipulation based-on a microring resonator. After a dark soliton pulse is fed into an input port of the microring, the orthogonal soliton pair (dark and bright solitons) can be formed within the system and detected simultaneously at the output ports. Under the resonant condition, the conversion of dark and bright solitons corresponding to the left-hand and right hand soliton orientations can be generated and seen. Whenever a soliton(photon) is absorbed by an object, an angular momentum of either + ħ or –ħ is imparted to the object, in which two possible soliton states known as soliton spins are exhibited and confirmed by the helical phase presentation. In application, the train of orthogonal solitons, i.e. many solitons (photons) with slightly different wavelengths can be generated by using the modified add-drop filter, which is available for many soliton spin investigations.

Controllable FWM within a PANDA Ring

In this paper, we present the controllable four-wave mixing (FWM) within PANDA ring resonator based-on optical soliton manipulation. After a dark soliton pulse is fed into an input port of the resonator, the FWM can be formed within the system and detected simultaneously at the output ports. Under the resonant condition, the FWM can be controlled by adding Gaussian or bright soliton at the add port. Whenever a soliton(photon) is absorbed by an object, an angular momentum of either + ħ or –ħ is imparted to the object, in which two possible soliton states known as soliton spins are seen. In application, the controllable FWM can be used atom/photon manipulation.

Dark pulses with tunable repetition rate emission from fiber ring laser

We demonstrated the experimental observation of the dark pulses with tunable repetition rate from an erbium-doped fiber ring laser. A considerable length of high nonlinear fiber is incorporated into the fiber ring laser to enhance the nonlinear intensity. In our experiment, both bright and dark pulses can be observed under the conditions of appropriately setting of the device in the cavity. Further study showed that the dark pulse is formed due to the cross coupling between two different lasing wavelengths. Particularly, dark pulse-train with multiple repetition rates was observed from the laser cavity and the repetition rate switchable operation can be realized by simply adjusting the polarization controller (PC) in the cavity. The operation of multiple repetition rates of dark pulses was further experimentally investigated and detected as a result of pulse splitting of each component with different wavelength.

Dark and antidark soliton solutions in the modified nonlinear Schrödinger equation with distributed coefficients in inhomogeneous fibers

We study a modified nonlinear Schrödinger model with distributed dispersion, self-phase modulation, self-steepening and linear gain/loss, which describes the ultrashort pulse propagating dynamics in inhomogeneous fibers. The dark and antidark soliton solutions are obtained with Hirota's bilinear method. The propagation dynamics and collision behaviors of the dark and antidark soliton pulses in inhomogeneous fibers are discussed by analyzing some important physical quantities and through graphical illustration. The inhomogeneous effects on the evolution and interaction for dark and antidark solitons are considered by virtue of the presented soliton solutions with distributed coefficients. Our analytical results could be applied to research on dark and antidark solitons in the dispersion-managed fiber system.

SOLITON SPIN AND WAVE-PARTICLE DUALITY

By using the optical add-drop filter which is formed by a microring resonator, and after a dark soliton pulse is fed into an input port of the add-drop filter, the orthogonal soliton pair (dark and bright solitons) can be formed within the system and detected simultaneously at the output ports. Under the resonant condition, the conversion of dark and bright solitons corresponding to the left-hand and right-hand soliton orientations can be generated and seen. Whenever a soliton (photon) is absorbed by an object, an angular momentum of either +ℏ or -ℏ is imparted to the object, in which two possible soliton states known as soliton spins are exhibited and confirmed by the helical phase presentation. In application, the train of orthogonal solitons, i.e. many solitons (photons) with slightly different wavelengths can be generated by using the modified add-drop filter, which is available for many soliton spins and long distance spin transport investigations.

Experimental observation of bright-dark pulse emitting in an all-fiber ring cavity laser

We demonstrate the emission of bright pulse and dark pulse in a simple all-fiber ring cavity laser by using self-pulsing technique. The switching between bright pulse and dark pulse can be realized by properly rotating the polarization controller (PC). Meanwhile, the bright-dark pulse can also be generated in the fiber laser and is experimentally verified to be on two different orthogonal polarization axis of the cavity fiber. Our experimental results show that the bright pulse, the dark pulse or the bright-dark pulse can be obtained in an all-fiber laser by using self-pulsing technique.

Dark pulse generation in a dispersion-managed fiber laser

We report an experimental observation of dark pulse generation in a dispersion-managed erbium-doped fiber laser with net anomalous cavity group-velocity dispersion. It is found that apart from the bright soliton pulses, dark pulses with spectral sidebands could be obtained in the laser under appropriate operating conditions. The generation of dark pulses may be attributed to soliton shaping in the cavity.

Generation of optical waveforms in 1.3-μm SOA-based fiber lasers

Passive optical waveform generation is obtained in fiber lasers using a 1.3-μm semiconductor optical amplifier (SOA) as the gain medium. Various waveforms, including square wave, staircase wave, triangular wave, pulse, and dark pulse are generated in SOA-based fiber lasers by adjusting intracavity polarization controllers. The passive waveform generation might be attributed to the SOA gain dynamics and the enhanced nonlinear interaction at the 1.3-μm zero dispersion wavelength of traditional single-mode fiber (SMF), as well as the interference effect between the two sub-cavities of fiber laser. With figure-8 cavity configuration, 1250th-order harmonic pulses have been successfully demonstrated. We have also obtained a free-running SOA-based fiber laser with 3-dB spectral width of 16 nm, and the center wavelength can be tuned over 45 nm range.

Klein-Gordon equation approach to nonlinear split-ring resonator based metamaterials: One-dimensional systems

The electrodynamics of a one-dimensional split-ring resonator (SRR) based nonlinear metamaterial is studied. The metamaterial is a one-dimensional periodic array of weakly coupled SRRs, with each SRR represented by a nonlinear resistor-inductor-capacitor (RLC) equivalent resonator circuit. Nonlinearity is introduced into the system by the addition of Kerr-type dielectric medium within the SRRs or by the introduction into the system of certain other nonlinear elements (e.g. diodes). In the continuum limit of the system, variations of the charge stored within the capacitive slits of the SRRs in both time and space are shown to be described along the array by a nonlinear Klein-Gordon equation. Analytical solutions of the nonlinear Klein-Gordon equation for various dark and bright envelope, breather, and pulse soliton solutions are obtained and studied. A discussion is given of the relationship between the Klein-Gordon solutions and the solutions of the nonlinear Schr\odinger equation approximation to the nonlinear Klein-Gordon equation. A comparison is made of the Klein-Gordon solutions with intrinsic localized mode (discrete breather) solutions of the discrete system and their continuum limits. An additional continuum limit differential equation for the breather modes of the system is obtained which is not bound by a weak coupling assumption, and its relation to the Klein-Gordon equation is studied. Analytic forms are given for the effects of dissipation in the system on the various bright and dark envelope, breather, and pulse solitons. Discussions are given of the effects of further than first neighbor couplings in the SRR system.

SPE analysis of high efficiency PMTs for the DEAP-3600 dark matter detector

The Dark matter Experiment using Argon Pulse-shape discrimination is a collaborative effort to develop a next-generation, tonne-scale dark matter detector at SNOLAB. The detector will feature a single-phase liquid argon (LAr) target surrounded by an array of 266 photomultiplier tubes (PMTs). A new high-efficiency Hamamatsu R877-100 PMT has been delivered to the University of Alberta for evaluation by the DEAP collaboration. The increase in efficiency could lead to a much greater light yield, but other experiments have reported a slower rise time [1],[2]. We have placed the PMT in a small dark box and had a base and preamplifier designed to be used with either an oscilloscope or a multi-channel analyzer. With this setup we have demonstrated the PMT's ability to distinguish single photo-electrons (SPE) and characterized the PMT by measuring the SPE pulse height spectrum, the peak-to-valley ratio, the dark pulse rate, the baseline, time resolution and SPE efficiency for varying the high voltage supplied to the PMT.

Generation of dark hollow femtosecond pulsed beam by phase-only liquid crystal spatial light modulator

Based on the refractive laser beam shaping system, the dark hollow femtosecond pulse beam shaping technique with a phase-only liquid crystal spatial light modulator (LC-SLM) is demonstrated. The phase distribution of the LC-SLM is derived by the energy conservation and constant optical path principle. The effects of the shaping system on the temporal properties, including spectral phase distribution and bandwidth of the femtosecond pulse, are analyzed in detail. Experimental results show that the hollow intensity distribution of the output pulsed beam can be maintained much at more than 1200 mm. The spectral phase of the pulse is changed, and the pulse width is expanded from 199 to 230 fs, which is caused by the spatial-temporal coupling effect. The coupling effect mainly depends on the phase-only LC-SLM itself, not on its loaded phase distribution. The experimental results indicate that the proposed shaping setup can generate a dark hollow femtosecond pulsed beam effectively, because the temporal Gaussian waveform is unchanged.