Fabrication of F-ion implanted quantum well intermixed waveguide grating

Abstract

This paper reports the ion implantation induced quantum well intermixing used to fabricate waveguide gratings for applications at CWDM wavelengths on InGaAsP/InP multi quantum well structure. The waveguide is fabricated using reactive ion etching (methane chemistry) with a surface roughness 2-3nm. Focused ion beam is used to open windows for fluorine implantation on titanium mask followed by anneal under forming gas environment. The transmission spectrum of the waveguide has been measured and found cross talks of -IOdB among the adjacent channels. The insertion loss of the fabricated waveguide gratings is less than 5dB. Keywords-waveguide; grating;quantum well; intermixing· insertion loss ' I. I NTRODUCTION Integration of discrete passive and active optoelectronics devices on a single chip brings numerous benefits in terms of reduced packaging cost, low power consumption, improved thermal and mechanical stability, high component density, and high functionality. Quantum Well Intermixing (QWI) [1] is a powerful technique for the fabrication of monolithic photonic integrated circuits. QWI is a post-growth modification of refractive index through modification of the energy band structure, which makes it, a very attractive technique for optoelectronic integration. It involves interdiffusion of atomic species of quantum well with atomic species in the barriers. QWI can be achieved by different techniques like impurity induced intermixing (III) [2], impurity free vacancy diffusion (IFYD) [3], laser induced intermixing (LID) [4], and photoabsorption induced disordering (PAID) [5]. Different QWI based devices have been proposed and demonstrated [6]. The impurity induced QWI (II-QWI) technique used here, involves impurity implantation and subsequent anneal, and is better suited for device design that are not close to the surface. This paper reports a fabrication and characterization of a single channel InGaAsP/InP multi quantum well (MQW) intermixed waveguide grating at 1570nm and 1590nm coarse wavelength division multiplexing (CWDM) wavelengths. Coupled mode theory [7] for grating and the perturbation analysis is used to calculate the reflection coefficient produced by the QWI. This requires prior calculations of the refractive index of bulk layers and that of the impurity induced MQW layer for different values of operational wavelengths. For the impurity induced MQWs it includes first, a calculation of the interdiffusion profile of the In, As, P and Ga species, followed by solving both the diffusion equation and Schrodinger wave equation's on a region containing quantum well. Finally, the dielectric constant is calculated to obtain the MQW refractive index at an operating wavelength. Atomic interdiffusion between the well and barrier atoms leads to changes in the shape of the quantum well. This modification in shape gives rise to changes in the absorption coefficient, refractive index and band gap. The detailed design analysis of the architecture is presented in [8]. II. E XPERIMENTAL D ETAILS The proposed geometry consi...

Electronic Band Structure of Quantum Cascade Laser

“…Due to the rapid advancement in microelectronics technology [64,65] in the last decade, research in the domain of semiconductor nanostructure has been carried out to a great extent by both theoretical [4,66] and experimental workers [5,6]. Quantum well waveguide is fabricated by ion implantation technique using InGaAsP/InP material composition.…”