The more finely you can slice the optical spectrum into distinct signal-carrying channels, the more data you can send through an optical fiber. That's the idea behind wavelength division multiplexing, which has brought tremendous data-carrying capacity to fiber-optic communications systems. Now Columbia, MD-based Essex has developed a variation on this technology designed to improve the lower-capacity optical networks extending from intercity fiber backbones into metropolitan areas. Essex's "Hyperfine" technology subdivides each optical channel into 50 to 100 subchannels, separated by less than a hundredth of a nanometer. So far, Essex has demonstrated this spacing over a wavelength band of about 0.1 nanometers, but the company plans to demonstrate an industry-standard 0.4-nanometer version early this year. In addition to providing better performance over existing fiber, the company claims the technology can better "tune" or control each of these channels, providing more flexible deployment of optical lines to specific corporate customers.