Equilibrium mode distribution

About: Equilibrium mode distribution is a research topic. Over the lifetime, 928 publications have been published within this topic receiving 14939 citations.

Failure of the scalar approximation near cutoff frequency of a step-index fiber mode

Abstract: The feasibility of the scalar approximation used in the theory of weakly-guiding optical fibers is considered near the cutoff frequency of the HE/sub 1n/(LP/sub 0n/) mode. The asymptotic behavior of polarisation corrections for transverse and longitudinal wavenumbers of a lossy fiber mode is investigated both analytically and numerically. These results as well as the transmittance calculated for an irregular fiber consisting of single-mode and bimodal segments demonstrate the failure of scalar approximation near the cutoff frequency.

Calculation of the Coupling Coefficient in Step-Index Multimode Polymer Optical Fibers Based on the Far-Field Measurements

Abstract: Using the power flow equation (PFE), this article investigates mode coupling in step-index (SI) multimode (MM) polymer optical fiber (POF). This equation’s coupling coefficient was initially fine-tuned so that it could appropriately reconstruct previously recorded far-field (FF) power distributions. The equilibrium mode distribution (EMD) and steady-state distribution (SSD) in the SI MM POF were found to be obtained at lengths L c = 15 m and z s = 41 m, respectively. These lengths are substantially shorter than their glass optical fiber counterparts. Such characterization of the investigated POF can be used in its employment as a part of the communication or sensory system. Namely, the POF’s bandwidth is inverse linear function of fiber length (z −1) below the coupling length L c . However, it has a z −1/2 dependence beyond this equilibrium length. Thus, the shorter the coupling length L c , the sooner transition to the regime of slower bandwidth decrease occurs. It is also important to be able to determine a modal distribution at a certain length of the POF employed as a part of optical fiber sensory system.

Phase rematch on overmoded waveguide mode converter for BWO

Abstract: The overmoded transmission line is often adopted by high-power millimeter wave system, so the influence of various distortion has to be evaluated. The distortion of waveguide can be utilized if we know its influence to the modes. So, the questions of mode coupling should be studied which arising from waveguide distortion. For the output mode of Backward wave oscillator and Virtual cathode oscillator is often TM01 mode and TM0n mixed modes. The TM0n-TM01 mode converter can adopt gradual radius changes of the waveguide, and TM01 mode radiate outside only converter to TE11 mode, so the thorough study of the structure and characteristic of TM01-TE11 mode converter is needed. The size of a waveguide is large under a high-power situation, thus it is necessary to take account more waves and their mutual coupling as well as the attenuation of circular waveguide and the option of coupling mode etc. Heavy considerations have been given to the influence of multimode factor, backward wave, ohmic losses carried from metal wall, modes choice and phase rematch.

Theoretical analysis of light transmission in a perfectly circular double clad fiber using coupled mode method

Abstract: Light propagation in a perfect circular double clad fiber (DCF) is numerically investigated by using the coupled mode method with translating the DCF into a single mode fiber (SMF) and an annular core fiber (ACF). The results show that for the coupling coefficients between the LP 01 mode of the SMF and the guided modes (LP 0n modes) of the ACF, the high-order mode has a larger coupling coefficient than the low-order mode for the ACF. By using the coupled mode equations the field distribution in the DCF core is calculated, the results show that the power shows a quasi-periodic distribution along the DCF core and its average period increases with increasing wavelength for different DCF parameters. The simulation results agree with the light ray propagation in the DCF.

Simple Technique for Measuring Higher-Order Mode Loss near Cutoff Wavelength Region

Abstract: We propose a simple technique for measuring higher-order mode losses based on the length dependence of the cutoff wavelength. Higher-order mode losses of the few mode fiber are successfully estimated by present technique.