Lightreading report from last weeks' optical conferences:
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Conference Review: Optical Amplifiers and Integrated Photonics Research topical meetings
7/17/2000 Two overlapping OSA meetings in Quebec City captured the technical thinking of leading optical component researchers. As usual, devices do more and come in smaller packages.
Aside from the beautiful location and ongoing street festival, Quebec City, Canada, was a very good place to be if you are researching or developing optical components. Well over 500 attendees crowded the conference rooms and small exhibit area of two topical meetings sponsored by the Optical Society of America (Washington, DC). The first, the 11th annual Optical Amplifiers and Their Applications (OAA) meeting, ran from July 9-12; the10th annual Integrated Photonics Research meeting ran from July 12-14.
Four types of amplifiers were in the spotlight. Erbium-doped fiber amplifiers (EDFAs) look to remain the dominant technology for long-haul communications (and probably for metro as well in the near term). On the other hand, discrete and distributed Raman amplification is finding great acceptance in long haul and is proving a complementary technology to EDFAs, especially for extending distances and power.
Planar or waveguide amplifiers appear to be rising quickly in acceptance, most likely as metro or access devices. And the SOA was the clear winner in terms of most frequently mentioned—if not yet commercially present--amplifier. Applications ranged from long-haul to access niches. Jay Wiesenfeld, a technology consultant at AT&T Labs and one of the technical program chairs, referred to SOAs as “Chevys”, meaning they may not offer high performance but they are potentially inexpensive (if the market is large enough) and well-suited for some applications.
Novel designs, integration
Distributed Raman amplification is increasingly important in the latest dense wavelength-division multiplexing (DWDM) experiments because it can reduce both nonlinear effects and noise. Another attractive feature is that the gain band is determined by the wavelength of the pump. In an interesting paper, Shu Namiki, from Fitel Photonics Laboratory of Furukawa (Chiba, Japan), described a multi-wavelength pumping scheme to achieve a broadband and flattened gain in Raman amplifiers.
High-power pump lasers from Furukawa and SDL were also of note. SDL (San Jose, CA) reported what it believed to be the first demonstration of 1450-nm narrow stripe laser diodes with power over 500 mW and distributed Raman gain of 14 dB.
Researchers from JDS Uniphase (San Jose, CA) and AT&T Labs (Red Bank, NJ) reviewed the recent achievements in DWDM transmission using SOAs. These ranged from 80 Gbit/s over distances up to 240 km, to transmission of 320 Gbit/s over 160 km of standard fiber plus dispersion compensation. A postdeadline paper from Lucent Technologies Bell Labs (Murray Hill, NJ) demonstrated SOA-based, 10-Gbit/s WDM transmission over 500 km of nonzero-dispersion-shifted fiber. This first long-haul demonstration of in-line SOAs used a novel wavelength modulation technique.
Siemen’s researchers provided a look at the next step in transmission line speed, 40 Gbit/s. They argued that the robustness and lower cost of electrical time-division multiplexing (ETDM) will make it the logical technology to team with WDM. Their electronics are based on Si/SiGe technology.
Integration, next generation
The Integrated Photonics Research meeting opened with reviews of the current state of component design and trends from A. Hadjifotiou at Nortel Networks (Harlow, England) and Joseph Ip at JDS Uniphase (Nepean, Ontario, Canada).
Reflecting the crossover to the OAA meeting (particularly regarding SOAs and waveguides), researchers at Lucent’s Bell Labs reviewed recent progress in erbium-doped waveguide amplifiers (EDWA). One of the manufacturers of these devices, Teem Photonics (Meylan, France), had presented a paper on ion exchange as a means of manufacturing EDWAs at the OAA.
High-speed optical integrated components were of great interest. Researchers at UCLA (Los Angeles, CA) described newly tailored chromophores they have developed to improve the nonlinearity of polymeric devices. They used the technology to fabricate new photonic microwave phase shifters, phased-array radars, and optical add/drop converters.
Pierre Doussiere at Alcatel Optronics (Nozay, France) described the development and use of an electroabsorption modulator integrated with a DFB laser diode (EA-ILM). He pointed out how the shift to 10-Gbit/s systems has created some challenges for manufacturers and some of the areas where design can be improved.
By Conard Holton
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