The thermal conductivity of self-assembled nanocomposite oxide films consisting of cobalt ferrite (CFO) spinel pillars grown within a single-crystal bismuth ferrite (BFO) perovskite matrix is described as a function of the volume fraction of the spinel. Single phase BFO and CFO had cross-plane thermal conductivities of 1.32 W m⁻¹ K⁻¹ and 3.94 W m⁻¹ K⁻¹, respectively, and the thermal conductivity of the nanocomposites increased with the CFO volume fraction within this range. A small increase (∼5%) in thermal conductivity for the pure CFO phase in the AC-demagnetized state was observed, suggesting possible magnon contributions. Steady state gray-medium based variance-reduced Monte Carlo simulations show consistent trends with experimental data on the dependence of thermal conductivity with the CFO volume fraction.

An ultracompact and broadband silicon wavelength demultiplexer based on SWG-assisted directional coupler is designed and experimentally demonstrated for wavelength splitting of 1310 and 1550 nm. The embedded SWG enables significantly reduced footprint, due to the precise phase matching at 1550 nm and large phase mismatch at 1310 nm. As a result, the fabricated device has a length of only 9 μm, and provides high extinction ratios (ERs) of 23 dB and 19 dB at 1310 and 1550 nm, respectively. Its 3-dB bandwidths are 85 nm for O-band (ER > 15 dB) and 140 nm for C-band (ER > 10 dB).

A controllable phase shifter is an essential part of spin-wave (SW) logic devices. Magnetic domain walls (DWs) as magnonic waveguides have been used to study SW propagation in ultrathin ferromagnetic films. In this study, we present a channel for SW propagation that relies on magnetic DWs as natural waveguides and realize phase manipulation by voltage-controlled magnetic anisotropy (VCMA) at a lower excitation frequency with micromagnetic simulations. The system model is a double-layer magnetic film structure, containing two oppositely magnetized domains and an upper layer (Co₂₀Fe₆₀B₂₀) coupled with the lower layer ([Co/Pd]) through exchange interaction. The pinning structure can effectively maintain the state of the waveguide during later operation without an additional magnetic field. By numerical micromagnetic simulation, we can clearly see that the exchange-dominated isotropic magnetostatic forward volume like SWs are confined in the Bloch-type DW. The phase accumulation by a propagating SW depends on the accumulated phase wave vector (k) and the distance traveled. Therefore, SWs accumulate more phase through DW waveguides covered by electrodes with different lengths. The phase of the SW is shifted after the SW passes through the voltage region, compared with the waveguide where a voltage is unapplied. As a result, the established phase shifter shows a phase difference of 2π by applying a voltage (E = 1 V/nm), and the length of the applied electrode is about 644 nm.

High-performance optical isolators are key components in photonic integrated circuits, with significant applications in nonlinear optical systems. We propose a design for a TE-mode optical isolator based on the AlGaAs-on-insulator platform. The isolator consists of non-reciprocal phase shift (NRPS) waveguides, reciprocal phase shift (RPS) waveguides, and multi-mode interference (MMI) couplers achieving low loss, high isolation, and wide bandwidth. Numerical simulations show that, at a wavelength of 1550 nm, the device provides a bandwidth of 91 nm at 30 dB isolation. The confinement factors for a magneto-optical (MO) waveguide were analyzed, and a detailed loss analysis revealed a total loss of 1.47 dB and a figure of merit (FoM) of 2.76 rad/dB. The manufacturing tolerances of the isolator are discussed referring to the requirement of stability and reliability in practical applications. This study provides an optimized design for high-performance TE-mode optical isolators in integrated photonic systems, which are well-suited for efficient and stable nonlinear optical applications.

An integrated optical isolator is a crucial part of photonic integrated circuits (PICs). Existing optical isolators, predominantly based on the silicon-on-insulator (SOI) platform, face challenges in integrating with active devices. We propose a broadband, compact TM mode Mach–Zehnder optical isolator based on InP-on-insulator platforms. We designed two distinct magneto-optical waveguide structures, employing different methods for bonding Ce:YIG and InP, namely O₂ plasma surface activation direct wafer bonding and DVS-benzocyclobutene (BCB) adhesive bonding. Detailed calculations and optimizations were conducted to enhance their non-reciprocal phase shift (NRPS). At a wavelength of 1550 nm, the direct-bonded waveguide structure achieved a 30 dB bandwidth of 72 nm with a length difference of 0.256 µm. The effects of waveguide arm length, fabrication accuracy, and dimensional errors on the device performance are discussed. Additionally, manufacturing tolerances for three types of lithographic processes were calculated, serving as references for practical manufacturing purposes.