A model of solitonic conduction in neuronal branchlets with microstructure is presented. The application of cable theory to neurons with microstructure results in a nonlinear cable equation that is solved using a direct method to obtain analytical approximations of traveling wave solutions. It is shown that a linear superposition of two oppositely directed traveling waves demonstrate solitonic interaction: colliding waves can penetrate through each other, and continue fully intact as the exact pulses that entered the collision. These findings indicate that microstructure when polarized can sustain solitary waves that propagate at a constant velocity without attenuation or distortion in the absence of synaptic transmission. Solitonic conduction in a neuronal branchlet arising from polarizability of its microstructure is a novel signaling mode of electrotonic signals in thin processes (<0.5 μm diameter).

An optical-based label-free biosensors including two indirectly coupled double-slot-waveguide-based microring resonator was designed and optimized for sensing purpose. Then, the optimized system was applied for the detection of hemoglobin concentration in anemia disease. The results were simulated based on the variational finite-difference time domain (varFDTD) method using the Lumerical software (Mode solutions) and the optimum geometrical parameters were determined to realize an optimum light transmission via the sensor. Nine different concentrations of hemoglobin in men and women were applied into the sensor and the status of anemia was identified based on the patients’ gender and different status of anemia disease, including the normal, mild, moderate, severe and life-threatening status. A sensitivity as high as 1024 nm/RIU with the minimum deflection limit of 4.88 × 10–6 RIU were measured for this biosensor, which introduces a high precision and micro-scale lab-on-a-chip micro device for health monitoring of the anemia.

A novel system of multisoliton generation using nonlinear equations of the propagating signals is presented. This system uses a PANDA ring resonator incorporated with an add/drop filter system. Using resonant conditions, the intense optical fields known as multisolitons can be generated and propagated within a Kerr-type nonlinear medium. The present simulation results show that multisolitons can be controlled by using additional Gaussian pulses input into the add port of the PANDA system. For the soliton pulse in the microring device, a balance should be achieved between dispersion and nonlinear lengths. Chaotic output signals from the PANDA ring resonator are input into the add/drop filter system. Chaotic signals can be filtered by using the add/drop filter system, in which multi dark and bright solitons can be generated. In this work multi dark and bright solitons with an FWHM and an FSR of 425 pm and 1.145 nm are generated, respectively, where the Gaussian pulse with a central wavelength of 1.55 µm and power of 600 mW is input into the system.

In this paper, the bifurcation behavior of light in the PANDA ring resonator is investigated using the signal flow graph (SFG) method, where the optical transfer function for the through and drop ports of the PANDA Vernier system are derived. The optical nonlinear phenomena, such as bistability, Ikeda instability, and dynamics of light in the silicon-on-insulator (SOI) PANDA ring resonator with four couplers are studied. The transmission curves for bistability and instability as a function of the resonant mode numbers and coupling coefficients for the coupler are derived by the SFG method and simulated. The proposed system has an advantage as no optical pumping component is required. Simulated results show that closed-loop bistable switching can be generated and achieved by varying mode resonant numbers in the SOI-PANDA Vernier resonator, where a smooth and closed-loop bistable switching with low relative output/input power can be obtained and realized. The minimum through-port switching time of 1.1 ps for resonant mode numbers of 5;4;4 and minimum drop port switching time of 1.96 ps for resonant mode numbers of 9;7;7 of the PANDA Vernier resonator are achieved, which makes the PANDA Vernier resonator an operative component for optical applications, such as optical signal processing and a fast switching key in photonics integrated circuits.

Nonlinear response of light such as bistability, the Ikeda instability and the dynamics of light within InGaAsPInP-modified add-drop resonator (PANDA Vernier resonator) is studied. The signal flow graph method is used to obtain the optical transfer function. Invariant and symmetric coupling coefficients k R = k L = 0.25 for indirect couplers are applied and the effect of changing symmetric direct couplers ( K 1 = K 2 ) for two different resonant mode numbers is studied. The minimum drop port switching time of 2.83 ps and 2.87 ps for resonant mode numbers of 7;5;5 and 4;3;3 are achieved, respectively. The simulated results introduce the PANDA Vernier system as a proper optical device for future optical communication and signal processing systems.Index Terms-Optical switching, bistable switching, PANDA vernier filter, optical bistability.

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In this paper, we introduced double-critical coupling condition (DCCC) for lossy mode couplers of the add-drop resonator to achieve the desirable and tunable signals required for optical communication and photonics sensors applications. The performance of add-drop resonator under double-critical condition is simulated and analyzed. Some equations were derived for optical parameters including full width at half maximum (FWHM), the out-of-band rejection ratio (OBRR), quality factor and the crosstalk of the add-drop resonator, and the output signals were examined as a function of DCCC. Based on double-critical condition, the OBRR values larger than 40 dB, the crosstalk larger than 50 dB, highest quality factor of 9000 and the FWHM as small as 0.17 nm were realized in silicon add-drop resonator, which are quite compatible with the reported experimental data. Double-critical condition shows that the lossless coupling is not enough condition to acquire high-quality filtered signal with a large crosstalk and in presence of coupling losses, the DCCC can determine the optimum relation between the strength of coupling coefficients and the coupling losses.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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