154-μm TM-mode waveguide optical isolator based on the nonreciprocal-loss phenomenon: device design to reduce insertion loss

Abstract

We developed a 1.5-microm band TM-mode waveguide optical isolator that makes use of the nonreciprocal-loss phenomenon. The device was designed to operate in a single mode and consists of an InGaAlAs/InP ridge-waveguide optical amplifier covered with a ferromagnetic MnAs layer. The combination of the optical waveguide and the magnetized ferromagnetic metal layer produces a magneto-optic effect called the nonreciprocal-loss phenomenon--a phenomenon in which the propagation loss of light is larger in backward propagation than it is in forward propagation. We propose the guiding design principle for the structure of the device and determine the optimized structure with the aid of electromagnetic simulation using the finite-difference method. On the basis of the results, we fabricated a prototype device and evaluated its operation. The device showed an isolation ratio of 7.2 dB/mm at a wavelength from 1.53 to 1.55 microm. Our waveguide isolator can be monolithically integrated with other waveguide-based optical devices on an InP substrate.

Ultrahigh-contrast-ratio silicon Fano diode

“…Up to now, many different mechanisms and methods to achieve ODs have been proposed, such as using metamaterials [1,2], tunable liquid crystals [3], nonreciprocal loss [4], Mach-Zehnder interferometers [5], cascaded gratings [6], nonlinear harmonic generation [7], indirect interband photonic transitions [8], and ferromagnetic structures [9][10][11][12][13][14]. The all-optical diode (AOD) is still being investigated for its advantages in all-optical operation, short relaxing time, and compactness.…”

TM mode waveguide isolator monolithically integrated with InP active devices

“…Figure 2 shows the calculated optical losses for the 1550nm TM mode as a function of p-InP(1) thickness d. The nonreciprocal loss (isolation ratio) is difference between the optical absorption loss of forward propagation and the one of backward propagation. This simulation is based on the scalar wave equation including off-diagonal elements in the dielectric tensor of the ferromagnetic layer and calculated with 2D-FDM [6]. As shown in Fig.…”

Low-cross-talk and high-contrast all optical bistable switching based on coupled defects in a nonlinear photonic crystal cross-waveguide geometry

“…By intentionally introducing defects into perfect PCs, various functional devices and large-scale integration of optical components can be constructed. All-optical switches, as one of the key components for future all-optical signal processing, have attracted much attention and have been extensively studied, and various methods for realizing switching function have been proposed such as those based on non-reciprocal media, liquid crystals, or nonlinearity [1][2][3][4][5][6][7][8]. Among these approaches, it has been shown that the use of nonlinear bistability in PC microcavities allows the construction of ultra-compact all-optical switches that operate with high speed.…”