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Optical reflection is an important concern in all commercial optical systems because of their potential performance degradation effects. Various approaches are employed to minimize the reflections in the optical couplings/connections, such as anti-reflective (AR) coating, index-matching fluids, and angled surfaces/facets. This manuscript investigates the Optical Return Loss (ORL) of different kinds of angled-facet waveguides using the power overlap between the incoming mode and the reflected one. We present a novel and straightforward analytic method to analyze the reflectance of tilted-facet waveguide modes with the advantage of no analytical approximation of the guided modes profiles that can be used to design integrated photonic waveguides. The dependence of the reflectance on the Mode Field Diameter (MFD) of optical fibers is examined. It is shown that an angle of 6 ∘ is sufficient to get an ORL of - 50 dB for an SMF-28 optical fiber. For High Numerical Aperture (HNA) fibers, an angle greater than 15 ∘ is necessary to achieve - 25 dB. In silicon photonics edge couplers, the reflectance is - 25 dB when the coupler is 15 ∘ tilted for the Transversal Electric (TE) polarization. Finally, the mode reflectance of a typical edge-emitting diode laser is also calculated for a tilted interface in two directions, and a dramatic difference between the reflectances is noticed, which is caused by the mode asymmetry. [ABSTRACT FROM AUTHOR]

The fundamental mode effective area of photonic crystal fiber (PCF) is calculated numerically using the cubic polynomial correction function as the correction factor of Marcuse and Petermann II equations. The numerical calculations are implemented using modified Marcuse and Petermann II methods for six different PCFs in the 1–2 μm wavelength range. The full-vectorial finite element method-based simulations are utilized to determine the effective area and coefficients of the cubic polynomial functions. After using the correction functions, by comparing the calculated effective area values with the values from the simulations, residuals of correction are obtained in the range of -1.11×10-3μm² – +2.66×10-3μm² and -1.4×10-3μm² – +5.112×10-3μm² respectively. These low residual values indicate that the offered method can be used successfully to calculate the wavelength-dependent effective mode area of PCFs in the investigated wavelength range without using simulations and complex theory. [ABSTRACT FROM AUTHOR]