Three key applications appear to be driving the development of new amplifier technologies:
All-optical crossconnects. These require amplifiers to compensate for losses in the optical signal as it traverses the switching fabric.
Pre-amplification. When amplifiers are used to boost the sensitivity of receivers, the system loss budget can be maintained when networks are upgraded from 2.5 to 10 Gbit/s.
"Banded" amplification. This term refers to amplifying channels in groups rather than all together.
The upshot of these emerging trends is the need for more amplifiers in the network and a corresponding requirement for amplifiers to be smaller, cheaper, and reliant on less power. What's more, these new applications don't require as much gain as traditional long-haul amplification, which opens the door to new amplifier technologies.
Here's a summary of recent developments in optical amplifiers:
Traditional EDFA vendors have given their products makeovers to fit them better to the new wave of applications. Just before the show, Alcatel Optronics (Nasdaq: ALAO; Paris: CGO.PA), Agere Systems (NYSE: AGR), and Nortel Networks Corp. (NYSE/Toronto: NT) announced a multisource agreement (MSA) that specified certain characteristics for compact amplifiers (see Major EDFA MSA Launched).
Independently, JDS Uniphase Inc. (Nasdaq: JDSU; Toronto: JDU) announced a broad range of standard amplifier products (see JDSU Unleashes Posse of Products and JDSU's Got New EDFAs). In the past, the EDFA business has revolved around customized products, which take longer to develop and deliver to customers. The emergence of standard products suggests that volumes will increase and prices will start to come down.
Gemfire Corp. unveiled an eight-port EDFA array for banded amplification (see Gemfire Demos Multiport EDFA). "It's like an EDFA and a dynamic gain equalizer rolled into one," says Rick Tompane, CEO of Gemfire. Instead of attenuating all the channels down to the weakest one before amplifying, individual channels or bands of channels get boosted up to the maximum. The result? Gemfire calculates that this technique might improve the system loss budget by nearly 10 decibels. Gemfire showed an eight-port pump laser array and an eight-port gain block at its booth. The two elements will be combined in the final product, which is set to sample at the end of Q2.
In a post-deadline paper to be presented tomorrow, Schott Telecom Optics GmbH will describe a new type of fiber for EDFAs (see Schott Intros Optical Fiber). The new fiber is "hundreds of times" better at absorbing light from the pump laser, so it's more efficient, says Torsten Holdmann, general manager for product development. "Instead of 15 meters of fiber, now you only need 15 cm [to make an EDFA]," he claims. Schott doesn't plan to make EDFAs, though; it hopes to sell its fiber to vendors like Corning and JDS Uniphase.
NP Photonics Inc. unveiled what it calls the first erbium micro-fiber amplifier (EMFA) (see Duo Launches New Acronym). Like Schott, NP has developed a speciality fiber with higher erbium concentration, so it's possible to use shorter pieces of fiber inside the amplifier. The difference, according to Schott's Holdmann, is that Schott's fiber offers broader gain as well as higher efficiency, making it possible for customers using the fiber to develop EDFAs that cover both the C and L bands of frequencies.
Cisilias A/S upped the ante on Gemfire with a demonstration at its booth of a 12-port amplifier gain block (see Cisilias Demos Amplifier). The gain block monolithically integrates five functions per amplifier port: input and output tap couplers for monitoring, a 980nm/1550nm multiplexer, an amplifying section, and pump kill filter. "This brings the total number of functions monolithically integrated in the 12-port amplifier array up to 60," the company notes. The 12-port device is only a technology demonstrator, however. Cisilias says its first products, which are expected in Q3 of this year, will probably have lower port counts.
Molecular OptoElectronics Corp. (MOEC) announced general availability of its WaveDæmon gain blocks (see MOEC Intros EDWA and VOA). This product takes on EDFAs on their home turf, being aimed at high-gain, multichannel amplification. It has a peak gain of more than 25 dB, and a noise figure of 5.5 dB. But being based on erbium-doped waveguides, the devices are much smaller than traditional EDFAs, the company claims.
Alcatel Optronics, JDS Uniphase, and Kamelian Ltd. announced an MSA for SOAs (see SOA Leaders Define Standard). Knowing that they have several product sources should give systems vendors more confidence to deploy SOAs, says Kamelian's CEO Paul May. Being part of the MSA is important to Kamelian, he adds, as systems vendors can be especially wary of buying from a startup.
Kamelian also announced commercial availability of two products for single channel amplification -- an optical pre-amplifier and an optical power booster (see Kamelian Launches First Products). At its booth, it also showed a four-port gain array, which includes four SOAs in the same package.