Coherent Grabs at Telecom Pie

R. Winn Hardin

SANTA CLARA, Calif. -- Hoping to grab part of the $2 billion suppliers' market to the optical communications industry, Coherent Inc. has entered into a joint venture with Fiber Optics Network Solutions Corp. of Northboro, Mass., to form CFX Communications Systems.
The new venture will target the smaller cable television delivery market with the release of a 1313-nm Nd:YLF transmitter with external modulator and two 17-dBm outputs.
Several companies offer self-modulated, distributed-feedback 1310-nm transmitters including Ortel Corp. of Alahambra and Harmonic Lightwaves Inc. Harmonic's system offers a single 13-dBm output and extended modulation output to 16 dBm, according to product manager of transmitter systems John Trail.
Jean-Michel Pelaprat, vice president of the commercial business unit at Coherent, said CFX hopes to capitalize on the lower dispersion factor of 1310 nm by offering a total fiber-to-the-home solution during the next year. The initial product offering is suitable for the head end of cable ring networks. Additional products will include smaller, less-expensive transmitters aimed at the nodal level and modules for narrowcasting, a technique that allows cable providers to replace national advertisements with local ads or programming.
According to established cable TV hardware suppliers such as Uniphase Telecommunications Products Inc. of Bloomfield, Conn., and Harmonic Lightwaves, CFX will have to overcome the power and dependability of 1550-nm diode technology if it is to succeed in grabbing a significant part of the estimated $700 million optical cable TV market.

The telecom angle
Some competitors question the wisdom of investing in 1310-nm technology when 1550-nm transmitters already control a large part of the cable TV trunk lines. "The technology of choice is 1550 because it has optical amplifiers," said Paul Suchoski, business development manager for Uniphase.
Part of CFX's charter is aimed at fixing that problem. Praseodymium-doped amplifers require a pump source at 1017 nm. Pelaprat hopes to enable mass production of praseodymium-doped fiber amplifiers for 1310-nm networks by introducing an optically pumped semiconductor source that is tunable between 800 and 1500 nm at 0.5 W.
The technology was developed by Micracor Inc. of Acton, Mass., and later purchased by Coherent in January 1997. Pelaprat said Coherent will demonstrate a prototype laser within two to four months and enter production by the end of the year. If so, besides a pump source for praseodymium, the laser could drastically reduce the number of pump sources for erbium-doped fiber amplifiers from six to two or fewer, based on its high-power output.
Suchoski also questions whether Coherent can deliver what Micracor attempted to do for nearly five years. "Even if it could be pulled off, there are probably manufacturing issues that will have to be overcome."