For the add/drop optical filter design, the effective mode core areas range from 0.10 µm2 to 0.50 µm2 and the parameters were obtained by using the related practical material parameters (InGaAsP/InP) [21]. When a dark soliton pulse is input and propagated within an add/drop optical filter as shown in Fig. 4.1, a resonant output is formed. The resonator output fields, Et1 and E1, consist of transmitted and circulated components of the add/drop optical filter system, which can act as driving forces for a photon/molecule/atom. For the first coupler of the add/drop optical filter system, the transmitted and circulated components can be written as t1 1 1 i1 1 41 1E E j E g k k (4.3) 1 1 1 4 1 i11 1E E j E g k k (4.4) n2 2 22 0 1 L LjkE E E e a (4.5) Here k1 is the intensity coupling coefficient, g1 the fractional coupler-intensity loss, a the attenuation coefficient, kn = 2p/l the wave propagation number, l the input wavelength light field, and L = 2pRad, where Rad is the radius of the add/drop device.
For the add/drop optical filter design, the effective mode core areas range from 0.10 µm2 to 0.50 µm2 and the parameters were obtained by using the related practical material parameters (InGaAsP/InP) [21]. When a dark soliton pulse is input and propagated within an add/drop optical filter as shown in Fig. 4.1, a resonant output is formed. The resonator output fields, Et1 and E1, consist of transmitted and circulated components of the add/drop optical filter system, which can act as driving forces for a photon/molecule/atom. For the first coupler of the add/drop optical filter system, the transmitted and circulated components can be written as t1 1 1 i1 1 41 1E E j E g k k (4.3) 1 1 1 4 1 i11 1E E j E g k k (4.4) n2 2 22 0 1 L LjkE E E e a (4.5) Here k1 is the intensity coupling coefficient, g1 the fractional coupler-intensity loss, a the attenuation coefficient, kn = 2p/l the wave propagation number, l the input wavelength light field, and L = 2pRad, where Rad is the radius of the add/drop device.
The parameters of the add/drop optical filter system are the same as in the previous section. In the system design, the dark soliton pulse is input into the input port through the coupler with the coupling coefficient is k1 = 0.35. It is partially input into the nanoring resonator with 20,000 roundtrips, where the storage signal is observed, the memory time is noted. The output field (Et1) at throughput port is expressed by E x x y E e x x E E e x x y y E E e x x y y E e k k k k k = - È ˘ +Í ˙+ Í ˙-Î ˚ (4.6) The power output (Pt1) at throughput port is given by The output field (Et2)at drop port is (4.8) The power output (Pt2) at drop port is (4.9) The optical tweezers storage signals within the add/drop system is as shown in Figure 4.4. We found that the storage time is 1.2 ns, the tweezer widths of the storage tweezers in add/drop at the throughput and drop ports are 19.2, 17.6 and 18.6 ns, respectively. In Figures 4.4 (a)–(b), the tweezers in the form of potential wells are seen. It can be used for atom/ molecule trapping. The potential well depth (peak valley) can be controlled by adjusting the system parameters, for instance, the bright soliton input power at the add port and the coupling coefficients. The potential well of the tweezers is tuned to be the single well and seen at the drop port, as shown in Figure 4.4(c). In application, the optical tweezers in the design system can be tuned and amplified as shown in Figures 4.2 and 4.4. Therefore, the tunable optical tweezers can be controlled by the dark-bright soliton collision within the add/drop optical system by adjusting the parameters of the input power at the input and add ports, respectively. The output power at the throughput port is shown in Figure 4.2(c), where the single potential well with the optical power of 15 W is seen.
Optical add-drop filters have been widely investigated in many areas of application, especially the use of an all-optical device which is formed with a modified add-drop optical filter known as a PANDA ring resonator [1-3]. By using an optical darkbright soliton control arrangement within a semiconductor add-drop multiplexer, promising applications have been observed [4]. In application, one of the advantages is that the dark soliton peak signal is always at low level, which is useful for secured signal communications in the transmission link. The other applications are associated with high-optical-field configurations (such as an optical tweezer or potential well) [5]. Spin manipulation has generated tremendous research progress in many fields, such as the light-shift effect in a rubidium atom [6], magnetic clusters [7], semiconductors [8], GaAs/AlGaAs quantum well [9], carbon nanotubes [10], thinfilm nanomagnets [11], magnetic tunnel junctions [12], and CdTe quantum dots [13]. All of these fields are based on pulsed magnetic resonance technique, which is well developed, but to date the single spin detection still remains a challenging task. The use of photon states for spin manipulation has become a promising technique of investigation, in which photons are the ideal candidates to transmit quantum information with little decoherency. Furthermore, spin states can be used to store and process quantum information due to their long coherence time. Therefore, the investigation of spin manipulation [14,15], spin detection, remote spin entanglement mediated by photons, and quantum-state transfer between photons and spins are of great importance. However, there is still a need to explore aspects of spin coupling and orbital motion of electrons in carbon nanotubes, magnetic manipulations, sidewall oxide effects on spin torque, magnetic field-induced reversal characteristics of thin-film nanomagnets, magnetic vortex oscillator driven by direct spin polarized current, and measurement of the spin transfer torque vector in magnetic tunnel junctions [16,17].
The proposed system consists of three optical devices, which are a PANDA ring resonator, an add/drop filter, and a Mach-Zehnder interferometer as shown in Figs. 2.1-2.3. The transmitter part of an optical cryptography system consists of a PANDA ring resonator, two add/drop filters, and a Mach-Zehnder interferometer. The receiver part consists of two add/drop filters and a Mach-Zehnder interferometer. An add/drop filter and the double microring resonators, together known as a PANDA ring resonator, are shown in Fig. 2.1. To perform the dark-bright soliton conversion, the dark and bright solitons are input into the add/drop optical filter. The input optical field (Ein) and the control port optical field (Econ) of the bright-dark soliton pulses are given by Eqs. 2.1 and 2.2 [15].
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.
The close form of Eq. (8.3) indicates that a ring resonator in the particular case is very similar to a Fabry-Pérot cavity, which has an input and output mirror with a field reflectivity, (1 – k), and a fully reflecting mirror. k is the coupling coefficient, and x = exp(–aL/2) represents a roundtrip loss coefficient, f0 = kLn0 and z kLn ENL in2 2= are the linear and nonlinear phase shifts, k = 2p/l is the wave propagation number in a vacuum, where L and a are a waveguide length and linear absorption coefficient, respectively. In this work, the iterative method is introduced to obtain the results as shown in Eq. (8.3), similarly, when the output field is connected and input into the other ring resonators.