News | January 13, 2004

NEC Releases High-Speed Laser Diode Modules with Built-in Wavelength Monitor

Enabling creation of compact economical DWDM system

Kawasaki, Japan and Duesseldorf, Germany -- NEC Compound Semiconductor Devices, Ltd. and NEC Electronics (Europe) GmbH today announced the availability of its newly developed laser diode modules featuring electro-absorption modulator distributed feedback (DFB) laser diode and built-in wavelength monitor enabling compact and economical dense wavelength division multiplexing (DWDM) optical transmission systems design.

The new laser diode modules are designed for use in backbone and metropolitan area networks (MAN) and are available in two device types (total 4 models): the NX8560SJ Series with a transmission rate of 10 gigabits per second (Gbps) and the NX8567SA Series with a transmission rate of 2.5Gbps. The products are designed for DWDM wavelengths from 1530 nanometers (nm) to 1560nm with 50GHz (0.4nm) spacing based on ITU (International Telecommunication Union; organization for establishing worldwide communication standards) recommendations.

The laser diode modules feature a built-in wavelength monitor with an etalon filter, which enables a precision-controlled emitted wavelength required from DWDM systems. These modules with built in wavelength monitor function reduce cost of optical transmitter by more than 25% compared with discrete solution where a monitor module is used externally. In addition, the size of the unit is reduced by up to two thirds, allowing a compact and economical DWDM system design.

To suit individual applications, two device types are offered. Customers can select from the 10Gbps NX8560SJ Series (1 model) and the 2.5Gbps NX8567SA Series (3 models) to match their application, allowing flexible system design.

The light source of the modules consists of:

  • A DFB laser diode which is driven by a constant current to reduce the "chirping", i.e., signal transmission distortion caused by wavelength variations.
  • A monolithically integrated electro-absorption modulator. This enables a transmission distance almost four times longer than that of a directly modulated DFB laser diode with a large amount of chirping.

"With the recent proliferation of home access network broadband services such as asynchronous digital subscriber line (ADSL) and fiber-to-the-home (FTTH), data transmission traffic are increasing continuously, resulting in the demand increase for larger transmission capacity in backbone and metropolitan area networks," said Masayuki Yamaguchi, department manager, 1st Optical Semiconductor Department, NEC Compound Semiconductor Devices. "Customers today require products that are optimized to their services and that can realize faster and more economical communication. The NX8560SJ and NX8567SA Series are the perfect solution for these requirements."

NEC Compound Semiconductor Devices will be exhibiting these new laser diode modules and related products at the 4th Fiber Optics Expo (FOE2004) - Asia's largest optical communications exhibition - held at Tokyo Big Sight in Koto Ward, Tokyo, from January 28.

Source: NEC