Platform manufacturing technique for next generation integrated photonic components

Abstract

EXTENDED ABSTRACTInnovation in integrated photonics and associated fields is imperative with looming bottlenecks in the existing internet infrastructure due to rapidly increasing demand, across society and industry, for greater bandwidth and data access. A priority in this field is the development of a monolithic photonic integrated circuit (PIC), simplifying the design, manufacture and material requirements of current devices, with reduced cost, power and footprints.Furthermore, an improved efficiency and performance is highly sought after as this market anticipates explosive growth. Typically the key components are often made through disparate methods, and then packaged together for a final device. This creates an exciting opportunity for a novel platform technology to overcome such limitations and enhance existing capabilities while opening up new frontiers in device design and complexity.The use of pulsed laser deposition in thin film fabrication has often been used for optical applications, but undesirable characteristics of the resulting films have habitually limited their applicability [1]. Modifications to this technique have allowed for a novel material manufacturing platform to be discovered which is capable of implanting a highly homogenous, metastable layer in an existing substrates surface, such as silica or silicon, called ultrafast laser plasma implantation (ULPI) [2]. A key characteristic in this process is the ability to implant large ionic radii elements such as lanthanides into a glassy matrix such as silica to depths of several microns, whilst maintaining the native glass network. This new approach is currently being investigated for doping rare earth ions such as Er 3+ to achieve at least two-orders of magnitude increase in optical gain [3]. In addition, extensive modification and densification of this implanted region leads to tremendous increases in the refractive index difference between the implanted region and the pristine substrate in excess of 10%. Both these characteristics are expressed in the EDX line scan of a cross section of a sample doped with Er in Fig. 1(a), further demonstrating the homogeneity of the dopants therein. Figure 1: (a) EDX line scan from the top surface (zero) through the interface (~ 900 nm) into the pristine silica; (b) SEM cross section of implanted sample, with the implanted region and pristine silica labelled as well as the platinum coating to protect the surface during extraction of this segment through focussed ion beam lithography.