Design and development of a package for a diluted waveguide electro-absorption modulator

Externally coupled electroabsorption modulators (EAM) are commonly used in order to transmit RF signals on optical fibers. Recently an alternative device design with diluted waveguide structures has been developed. [1] Bench tests show benefits of lower propagation loss, higher power handling (100 mW), and higher normalized slope efficiency. This paper addresses the specific issues involved in packaging the diluted waveguide EAM devices. An evaluation of the device requirements was done relative to the standard processes. Bench tests were performed in order to characterize the optical coupling of the EAM. The photo current maximum was offset from the optical power output maximum. The transmissions vs. bias voltage curves were measured, and an XY scanner was used to record the mode field of the light exiting from the EAM waveguide in each position. The Beam Propagation Method was used to simulate the mode field and the coupling efficiency. Based on the bench tests and simulation results, a design including mechanical, optical and RF elements was developed. A Newport Laser Welding system was utilized for fiber placement and fixation. The laser welding techniques were customized in order to meet the needs of the EAM package design.