Theory of Chaotic Dynamics on Class A Laser with Optical Delayed Feedback

Abstract

Experiments on the iron-pnictide superconductors appear to show some materials where the ground state is fully gapped, and others where low-energy excitations dominate, possibly indicative of gap nodes. Within the framework of a five-orbital spin fluctuation theory for these systems, we discuss how changes in the doping, the electronic structure or interaction parameters can tune the system from a fully gapped to a nodal sign-changing gap with s-wave (A 1g ) symmetry (s ± ). In particular, we focus on the role of the hole pocket at the (π, π ) point of the unfolded Brillouin zone, identified as crucial to the pairing by Kuroki et al (2009 Phys. Rev. B 79 224511), and show that its presence leads to additional nesting of hole and electron pockets, which stabilizes the isotropic s ± state. The pocket's contribution to the pairing can be tuned 7 2 by doping, surface effects and by changes in interaction parameters, which we examine. Analytic expressions for orbital pairing vertices calculated within the random phase approximation (RPA) fluctuation exchange approximation allow us to draw connections between aspects of the electronic structure, interaction parameters and the form of the superconducting gap. Contents

Effects of Polarization on a Single-mode Class A Laser

“…(23) in ref. 12). Of course, the electric field slaves the population inversion and electric dipole moments that have very faster decay rates than that of the electric field.…”

“…Recently, as reported in our previous papers, the chaotic oscillation of a single mode class A standing wave laser has been observed by optical delayed feedback using an external resonator [9][10][11] . The chaotic dynamics of a single-mode class A laser with optical delayed feedback has also been investigated theoretically 12) . In that paper, we derived the equation for the single-mode class A laser equation and using this model, the characteristic frequency is deduced as the round-trip frequency.…”

Optimizing the external optical cavity parameters for performance improvement of a fiber grating Fabry–Perot laser

“…The delayed feedback system is infinity degree of freedom system [48,49] and in the case of grating optical feedback from the fiber Bragg grating, multiple reflections must be taken into account, especially if the model works in Regime IV [38]; however, by optimizing the laser, we pushed it to work in Regime V. In this case, the rate equations approximation can be used without considering multiple reflections. By considering the effect of temperature and external OFB described in the previous section, the noise characteristics of FGFP laser can be derived from the well-known coupled rate equations [34], after taking into account the effect of external OFB and temperature variation.…”

Chaotic He-Ne laser

“…There are only a few studies on chaotic He-Ne lasers and most of them were made by Kuwashima et al In these studies, optical feedback in the form of an external mirror was used. They found both in numerical analysis [14] and experiments [15,16] that the output intensity of the He-Ne laser can oscillate chaotically. They also used a periodically driven mirror [17] or a very long optical delay [18] in similar studies.…”