IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 15, NO. 2, FEBRUARY 2003 299 A Novel Method for Fabrication of a Hybrid Optoelectronic Packaging Platform Utilizing Passive–Active Alignment Madhumita Datta, Member, IEEE, Zhaoyang Hu, and Mario Dagenais, Senior Member, IEEE Abstract—We present a novel fabrication method for a hybrid optoelectronic packaging platform using a combination of passive and active alignment. -grooves on a silicon optical bench facilitate coarse passive alignment, while on-board thin-film heaters enable final active alignment. The passive–active align- ment technique ensures 50% peak-coupling efficiency from a semiconductor laser diode with a single-mode conically lensed fiber, making it a low-cost packaging solution appropriate for a variety of optoelectronic modules. Index Terms—Hybrid integration platform, passive–active alignment, silicon optical bench, thin-film heaters. I. INTRODUCTION H YBRID INTEGRATION enables the realization of var- ious photonic functional blocks, such as optical switches (OSs), wavelength converters (WCs), multiplexers/demulti- plexers for wavelength-division multiplexing (WDM), etc. Packaging procedure of the individual components dominates the overall product cost of an optoelectronic (OE) module. Therefore, improvement of optical coupling between active devices and optical fibers has been a crucial issue to achieve low cost and compact size of OE modules, while maintaining the desired functionality and performance [1]. The coupling of the optical fiber to the optoelectronic devices by active alignment accounts for a significant portion of the cost, especially in the unconventional coupling schemes required for Mach–Zehnder (MZ) interferometer WC or 1 2 OS, etc. To date, many investigations and developments have been reported based on passive alignment techniques to facilitate low-cost mass production [2], [3]. Although passive alignment technology for a hybrid integrated optical module has the potential for low-cost implementation, it is mainly limited by the accumulation of misalignments during the fabrication process [4]. In this letter, we present a novel fabrication method and structure of a packaging platform for the hybrid integration of an optical device by a combination of passive and active alignment. First, the active device is soldered onto the silicon optical bench (SiOB) using passive alignment with the help of fiducial marks. Next, metallized lensed fibers are solder Manuscript received July 1, 2002; revised October 1, 2002. M. Datta and M. Dagenais are with the Department of Electrical and Com- puter Engineering, University of Maryland, College Park, MD 20742 USA. Z. Hu was with the Department of Electrical and Computer Engineering, Uni- versity of Maryland, College Park, MD 20742 USA. He is now with the Depart- ment of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106 USA. Digital Object Identifier 10.1109/LPT.2002.806090 Fig. 1. Proposed hybrid optoelectronic packaging platform. attached inside the -grooves of separate silicon fiber-holder blocks. Then, the silicon fiber-holder blocks are mounted on the SiOB such that the fibers are automatically placed inside the solderless -grooves etched on the SiOB itself. The integrated -grooves on the SiOB are defined in such a way that coarse lateral alignment between the device and the fibers can be obtained through the passive-alignment step. During this step, the critical height accuracy is not needed, because the vertical alignment is assisted with thick solders deposited on the thin-film heaters during subsequent active alignment as described in more detail below. Active alignment completes final accurate lateral and vertical alignments by heating and refreezing the solders with localized thin-film heater on the SiOB so as to adjust the position of the fiber for peak efficiency. The passive–active-alignment technique offers important ad- vantages over other solely active or entirely passive alignment schemes, because it alleviates the SiOB fabrication difficulty to a great extent, while ensuring micron-level positional accuracy required for single-mode lensed fiber alignment with optimum coupling efficiency. II. HYBRID PLATFORM CONFIGURATION The proposed packaging platform structure is shown in Fig. 1, where a 1 2 active device (such as 1 2 OS or MZ interferom- eter WC) is mounted directly on the SiOB. The hybrid platform consists of two parts: One part is the SiOB as the fundamental motherboard, and the other part is the two silicon fiber-holder blocks, i.e., Block-1 and Block-2, to hold the input and output 1041-1135/03$17.00 © 2003 IEEE