Broadband multifunctional plasmonic polarization converter based on multimode interference coupler

We propose a multifunctional integrated plasmonic–photonic polarization converter for polarization demultiplexing in an indium-phosphide membrane on silicon platform. By using a compact 1 × 4 multimode interference coupler, this device can provide simultaneous half-wave plate (HWP) and quarter-wave plate (QWP) functionalities. Our device employs a two-section HWP to obtain a very large conversion efficiency of ≥ 91% over the entire C to U telecom bands, while it offers a conversion efficiency of ≥ 95% over ∼ 86% of the C to U bands. Our device also illustrates QWP functionality, where the transmission contrast between the transverse electric and transverse magnetic modes is ≈ 0 dB over the whole C band and 55% of the C to U bands. Using this functionality, our device generates two quasi-circular polarized beams with opposite spins and topological charges of l=±1, based on only one input polarization, and one incoming light beam direction. We expect that this device can be a promising building block for the realization of ultracompact on-chip polarization demultiplexing and lab-on-a-chip biosensing platforms. Finally, our proposed device allows the use of the polarization and angular momentum degrees of freedom, which makes it attractive for quantum information processing.</p

Miniaturization of 90-degree hybrid optical couplers

Here we explore the limits of miniaturization of an efficient 90-degree hybrid coupler on the InP photonic integration platform, working in the L, C and S bands, with respect to their figures of merit. We investigate the main effects responsible for the degradation of the performance of the devices, and establish the minimal dimension that such devices can have without significant degradation for photonic applications. The miniaturized device has a footprint of only 2200µm2, more than 5 times smaller than the conventional device used as reference

Miniaturization of 90-degree hybrid optical couplers

Here we explore the limits of miniaturization of an efficient 90-degree hybrid coupler on the InP photonic integration platform, working in the L, C and S bands, with respect to their figures of merit. We investigate the main effects responsible for the degradation of the performance of the devices, and establish the minimal dimension that such devices can have without significant degradation for photonic applications. The miniaturized device has a footprint of only 2200µm2, more than 5 times smaller than the conventional device used as reference

Analysis of Etch Depth for Polarization-free Directional Couplers

We numerically analyze the etch depth as a design parameter for the realization of integrated polarization independent directional couplers. Through finite-element-method simulations, the coupling coefficients of transverse-electric (TE) and transverse-magnetic (TM) polarizations are investigated according to different etch depth levels in the coupling section of the studied device. By optimizing etching depth, the proposed coupler can perform similarly for both polarizations in broadband. According to simulation results, the minimum difference between the TE and TM coupling coefficients can be kept less than 1% in 100 nm of the wavelength range.</p

Understanding the interaction of photonic waveguides with magnetic multilayers for ultra-fast memory devices

Increasing rates of data consumption require development of new devices for digital communication and data storage. Devices with integrated magnetophotonics are expected to deliver an answer since photons can facilitate ‘writing’ [1] and ‘reading’ of magnetic information stored in metallic multi-layers via spintronic manipulation on ultrafast timescales. This work plays an important role to realize a magnetophotonic device for on-chip all optical reading of magnetic information, i.e. combining racetrack memory with photonics

Efficient and fabrication error tolerant grating couplers on the InP membrane on silicon platform

In order to couple light between photonic integrated circuits and optical fibers, grating couplers are commonly employed. This paper describes the design and fabrication of deep and shallow-etched grating couplers with a metal back-reflector with record low insertion losses in InP-based platforms. The measured insertion losses for deep and shallow-etched gratings are 2.4 and 2.6 dB, respectively. Additionally, fabrication error tolerances in shallow etched grating couplers have been examined experimentally, which showed high tolerance of this structure toward the grating period and fill factor