Effective Pigtailing Method for Fiber Arrays to InP-Based Photonic Integrated Circuits

A reliable technology for interfacing signals in both the optical and electrical domain that provides the possibility of precise control of the thermal optical chip properties is an essential requirement to utilize photonic integrated circuits in system-related areas. Hence, a practical assembly method is developed here to connect fiber arrays to a wide range of different kinds of advanced indium phosphide-based photonic integrated circuits. The essence of this procedure is a well-controlled step-by-step pig-tailing approach whereby any misalignments during the assembly process can be compensated for using laser supported adjustment. The pigtailing process of two different multiport photonic integrated circuits is described. The circuits include an integrated two-state multiwavelength laser chip, operating at 25degC, and a coupled Mach-Zehnder interferometer chip, operating at 10degC. Both devices function as a 1 bit optical memory element with optical set and reset functions. Successful alignment compensation on the order of 0.1-3 mum is demonstrated. Subsequently, the subassemblies are fixed unambiguously on thermo-electric coolers in a package with a clamp method to reduce internal stress in the subassembly. Consequently, the mechanical alignment stability of both devices are proven to be smaller than 25 nm/degC, as measured in a temperature range from 10degC to 30degC.