Hewlett Packard singlemode Small Form Factor (SFF) module incorporates micromachined silicon, automated passive alignment, and non-hermetic packaging to enable the next generation of low-cost fibre optic transceivers

Hewlett Packard (HP) is currently manufacturing a range of multimode and singlemode (SM) SFF transceivers with data rates from 125 Mb/s to 1.25 Gb/s (higher data rates are being developed). This paper addresses the singlemode module design, assembly techniques and performance. HP SFF transceivers offer the same functionality as SC duplex transceivers but utilise the mini MT-RJ optical interface in order to achieve twice the port density. HP SFF modules are price competitive with SC duplex modules, and are designed to enable low cost, high volume manufacture. In order to meet the size constraints and achieve low manufacturing costs, the HP SM SFF transceiver utilises silicon as a base to support the optical fibres and active components, and as an aid to passively align of the active components to the fibres. Most other passively aligned modules require the use of a more expensive expanded mode region laser diode (LD). But HP has developed a unique passive align and attach system that can easily achieve the required coupling power for Fast Ethernet, OC3 and Gigabit Ethernet using a standard 1300 nm strained MQW LD. The module design and the methods used for passive align are discussed, as is the precision die attach (PDA) equipment. All previous HP SM modules relied on an hermetic cavity around the active devices to achieve the reliability assurance, e.g. as defined in Bellcore TA-NWT-000983, but this type of hermetic design has limited potential for cost reduction. The HP SM SFF module is designed to meet the same assurance levels, but uses silicone encapsulation in place of hermeticity, and the results of the qualification testing are presented