Inp Based Monolithically Integrated Devices For All-optical Signal Processing

The21st century witnesses information explosion and the ever-developing demand of data communication imposes a higher and higher requirement on the capacity of communication systems. The all-optical signal processing technology has been widely studied owing to that it can potentially remove the O/E/O conversion at network nodes and thus overcome the limitation of data rates. Photonic integration provides a feasible approach for all-optical signal processing technology to be applied in optical communication networks due to its low cost, low energy-consumption and high reliability. Photonic integration is regarded as one of the technologies that can lead the future of optical data communications.The operation wavelength of InGaAsP is1.0μm-1.65μm, and can be adjusted flexibly to obtain passive material and active material, while maintaining lattice matching with InP substrate, which makes it a perfect material for photonic integrated circuits. This thesis first studies the methods of monolithic integration with InP-based materials. Then, with the developed manufacturing processes on the InP platform, passive components, active components, monolithically integrated semiconductor optical amplifier (SOA) and delayed interferometer (DI), are designed, fabricated and tested. Finally, these devices are applied in all-optical signal processing. The major research achievements and contributions are summarized as follows:(1) Studies have been focused on both QWI and ATG integration methods. The mechanism of QWI integration method is first introduced as well as several typical techniques to realize QWI. Based on the atom diffusion mechanism of III-V semiconductors, the argon plasma enhanced quantum-well intermixing (Ar-PEQWI) technique is analyzed in details. A bandgap blue shift of110nm has been achieved. Next, the principles of the asymmetric twin-waveguide (ATG) technique are analyzed. The key element of the ATG structure, taper, is subsequently analyzed and designed. A single bevel taper with simplified fabrication process is proposed. Moreover, an ultra-short coupler is designed for the ATG integration structure by applying transformation optics, the3-μm-long coupler characterizes a high coupling efficiency of94.9%. Finally, based on the QWI and the ATG techniques, the fabrication processes of monolithically integrated device with SOA and DI are designed.(2) The mask layouts of the SOA and DI monolithically integrated device are designed. The structure of the multiple quantum wells epitaxial wafer and the sizes of SOA are first determined. The InP passive straight and bend waveguides are then designed according to the finite element method. The operating principle of multimode interference (MMI) couplers is introduced and1×2/2×2MMI couplers are therefore designed. The layout sizes of DIs are subsequently determined to meet their operating bandwidth. In the last, the mask layouts including integrated passive and active components are designed.(3) The key fabrication processes of monolithically integrated devices on the InP platfrom are studied and developed, including ultraviolet lithography, wet etching, magnetic enhanced reactive ion etching (MERIE), inductively coupled plasma (ICP) etching, metal deposition, lift-off, die-bonding, wire-bonding and et. al. The developed fabrication processes are capable of manufacturing the InP-based photonic integrated devices that can be used for all-optical signal processing.(4) The passive, active and monolithically integrated devices are fabricated and measured. Passive ridge waveguides with single-mode and multi-mode operation are first demonstrated. Then, the detailed manufacturing processes of Fabry-Perot semiconductor optical amplifier (FP-SOA) are introduced, and a FP-SOA with a high extinction ratio of30dB is fabricated successfully. Finally, the SOA and DI monolithically integrated devices are realized and measured. The saturation output powers of the2000-μ,m-long SOAs in the integrated devices are higher than3dBm, the extinction ratio of the tunable DI with a phase shifter is16dB, and the arrayed waveguide grating shows an extinction ratio higher than20dB.(5) The all-optical signal processing based on InP-based devices is investigated. All-optical1st-and2nd-order differential equation solvers with large tuning ranges using FP-SOAs are proposed and demonstrated. By simply changing the injection currents of FP-SOAs, a quite large constant coefficient tunable range from0.0026/ps to0.085/ps is achieved for the lst-order differential equation, and the two constant coefficients of the2nd-order ODE solver can be tuned from0.0216/ps to0.158/ps and0.0000494/ps2to0.006205/ps2. Then, based on four-wave mixing and corss gain modulation, all-optical wavelength conversion and wavelength multicasting at lOGbit/s are experimentally demonstrated by using the SOA and DI monolithically integrated device.