Laser makers opt for standard size

Laser makers opt for standard size

yvonne carts-Powell

An agreement on the packaging of diode lasers for telecommunications by three major manufacturers aims to create a de facto industry standard for the local access market. Consensus was reached on a common size and pin-out structure for diode lasers--13.2 ¥ 7.6 mm and 8 pins--in addition to pin-compatibility with 14-pin dual-inline (DIL) packages (see figure).

The three laser makers--Northern Telecom Ltd. in Paignton, UK; Hitachi Ltd. in Tokyo and Lucent Technologies in Berkeley Heights, NJ--are encouraging designers to use their standard instead of customizing a component for each application. This standard would provide economies of scale for the manufacturers, which, in turn, could then reduce prices. The ability to design a system using a source available from three suppliers is also seen as a major cost incentive to users.

Although the standard could be used to design sources for long-haul trunk applications, the agreement focuses on access markets, which are generally short-distance lines closer to the customer--fiber-to-the-curb systems would be considered access systems. According to analyst Jerry Hobbs at Kessler Marketing Intelligence Corp. (KMI), an international fiber-optics market research firm in Newport, RI, 72% of typical U.S. networks comprise access lines, which contain a limited amount of fiber at this time.

However, fiber has saturated the long-haul portion of networks. In the past three years, it has gained approximately half of the intermediate feeder parts of these networks. According to Dave Buckley, company spokesman at Northern Telecom, there is a strong demand for E1 and E3 lines. "The market is nowhere near mature," says Buckley. He expects to see explosive growth in optoelectronics for access through the year 2001. The access market requires a singlemode laser.

Tom Dudley, optoelectronics device product manager at Lucent Technologies, explains why the companies believe that this move will cause the access market to grow faster. By standardizing the size and pin-outs of the laser, companies provide benefits to customers, including a short design time and the ability to buy components from multiple sources. Buckley notes that the access market has had "a high degree of custom specification."

Advantages of the standard laser allow high-volume production, which in turn, leads to lower prices. As a result of the joint announcement, it is expected that industry support for the component will accelerate the installation of reliable networks to deliver high-bandwidth added-value services, such as fast data, Internet access and interactive TV.

John Kulnick, product manager for optoelectronic products at AMP Inc. in Somerville, NJ, however, believes that cost-competitive applications, not component availability, will drive this market. He adds, "It`s always dangerous to try and tell customers what they want," and points out that customers with existing systems would have to redesign boards and requalify their products if they were to conform to the new standard.

But can these three suppliers, in fact, implement a de facto standard? According to a KMI study of the 1994 market, Lucent (at that time known as AT&T Microelectronics) had sales figures of approximately $150 million for singlemode optoelectronics worldwide. In 1994, Northern Telecom sold approximately $100 million to $125 million in sources, and Hitachi sold from $75 million to $100 million in singlemode optoelectronics, says Hobbs. He estimates that Northern Telecom, Hitachi and Lucent control almost 50% of the optoelectronics market. Buckley of Northern Telecom also estimates that the three companies hold about half of the worldwide market, making this a significant partnership.

The telecommunications laser packaging design that the three manufacturers have agreed upon is pin-compatible with 14-pin DIL lasers and meets Bellcore 983 environmental conditions. Buckley explains that these stringent standards for commercial telecommunications components require that the laser operate in an uncontrolled environment between -40° and +85°C, through temperature cycling.

Lasers in the 14-pin DIL package have been around for several years. When the design was developed, explains Kulnick, the lasers required thermoelectric coolers, and the flat surfaces worked well for heat transfer; however, they were difficult to package with fiber. The fiber had to come into the side wall and be aligned. Then, the package was hermetically sealed. "It was not a manufacturer-friendly process," says Kulnick of AMP. Coaxial-cable packages let manufacturers use their experience in transistor-outline-style packaging and allowed the fiber to be placed outside the hermetically sealed package.

Although 14-pin and coaxial-cable packages are current market standards, individual vendors vary the leads and sizes of the lasers, explains Dudley of Lucent Technologies. One obvious advantage of the 8-pin lasers is the savings in printed circuit board space. Also, because of its low profile, says Buckley, the design allows boards to be packed closer together.

Packaging technology

To gain the economies of scale that manufacturing companies want, not only must they receive a large number of orders, but also the packaging technology must be efficient. Kulnick comments that the laser chip only represents a minor cost of today`s transmitters.

The lasers are based on silicon submount technology, which companies and competitors agree can offer economies of scale. Dudley explains that optical components are mounted on a silicon optical bench platform using high-volume manufacturing methods. This technology improves performance and stability because the silica (fiber) and silicon have similar coefficients of expansion.

The flat package is also easier to assemble, according to the companies, because the laser requires no lead bending, unlike the transistor-outline package. Kulnick says AMP is also developing silicon submount technology, but today`s cost may be too high to justify its use.

Northern Telecom already has a laser that meets the terms of the agreement. This laser and a corresponding mini-DIL receiver are available in volume. Later this year, Lucent will introduce products that can be made using high-speed automated processing (see photo). q

Yvonne Carts-Powell writes from Belmont, MA.

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