JDS Uniphase tips integrated modulator

Colorado Springs, Colo. - JDS Uniphase Corp. will show its first prototypes of a tunable-laser modulator this week in Los Angeles at the Optical Fiber Communication Conference & Exposition. The Integrated Laser Modulator combines a tunable laser based on a distributed-feedback (DFB) array with a lithium niobate modulator, wavelength locker, photodiode and optional variable optical attenuator.

The module is the first to offer full tunability in both C and L bands, said Charles Neagoy, senior product line manager of JDS Uniphase's modulator group. Designers looked at external-cavity lasers, DFB arrays and distributed Bragg reflectors as possible laser-source designs and opted for a DFB array with a MEMS mirror as the best to integrate with other functions, he said. DFB arrays also were the most stable, showing none of the mode hops occasionally seen in other tunable-laser sources, Neagoy said. The resulting device can fit into a 10-Gbit multisource-agreement transponder package for next-generation line cards, JDS Uniphase said.

Since the modulated output power is 4 dBm, the device does not need a transmit amplifier. A single package design can be used for both long-reach applications of up to 120 km and long-haul applications of up to 1,600 km, changing only the type of modulator chip within the package. Designs with or without the variable optical attenuator also differ in only a single chip, the company said.

Typical power dissipation is less than 3.8 watts. A power tap optimizes both the power and the lithium niobate bias, while a wavelength locker is used to ensure wavelength stability.

The C-band output spectra show a side-mode suppression ratio in excess of 50 dB, offering 5 dBm of modulated power, the company said. Tests show consistent eye diagrams every 500 GHz between 191.5 THz and 196 THz.

An initial ILM package with two-sided pinout placement is being replaced by a design with single-side pinout. Orders will be taken and pricing announced in April. In general, the company said pricing will be around 60 percent that of a discrete solution.