Lucent Technologies Inc.

Rene Henri Monnard

Christopher Richard Doerr

Charles H Joyner

Lawrence Warren Stulz

Mujibun Nisa Khan

Martin Zirngibl

Temperature compensation of a wavelength-division-multiplexed (WDM) passive optical network (PON) communication system uses power measurements from each of it remote nodes (RNs) to adjust the frequency of an associated multifrequency laser (MFL). Changes in the power level at each RN caused by frequency drift of its waveguide grating router (WGR), due to changes in the WGR temperature, is determined by monitoring the power level received at each RN and corrected by appropriate changes in the temperature of the associated MFL. The WGR uses one output port (e.g., channel,) which is looped-back through the WGR a second time to increase the temperature sensitivity of the power measurements. A temperature-control algorithm controls the temperature of the MFL as a function of changes in the received power at the WGR.

Temperature compensated multi-channel, wavelength-division-multiplexed passive optical network

Changing the index in the two output branches of a Y-branch optical waveguide in opposite directions, in amounts which are controlled by electrical signals applied to the branches, is used to control the chirp of the signal outputted from the Y-branch optical waveguide. In this manner, predetermined amount of chirp can be add to or subtract from an input signal to the Y-branch optical waveguide. The Y-branch optical waveguide can be fabricated using Group II-VI, Group III-V or Group IV material systems or using an insulating material, such as lithium niobate. The output branches of a semiconductor implemented Y-branch optical waveguide can be fabricated to each include a multiple quantum well for controlling the refractive index of that branch in response to an electrical signal.

Adiabatic Y-branch waveguide having controllable chirp

Methods of using an adiabatic Y-branch digital optical modulator provide a substantially chirp-free modulator by changing the refractive index of only a first output branch of the modulator in response to a modulating signal. A second output branch of the modulator, where no refractive index change is induced, is used as the modulator output. The frequency chirp in this Y-branch modulator is negligible because the modulator output waveguide branch experiences little or no refractive index change and, therefore, little or no phase shift in operation. Substantially all of the phase shift occurs in the waveguide branch where the refractive index change is induced. According to a further embodiment, one or both of the output branches are comprised of one or more tapered waveguide sections.

Adiabatic Y-branch modulator with negligible chirp

A multifrequency laser (MFL) eliminates nonlinearities produced in the 'shared' waveguide of the MFL laser (the section in which all the lightwaves from all the lasers pass) by either making the shared waveguide as short as possible to mimimize the production of mixing product signals or using a channel spacing that is unequal such that any mixing product signals formed from the multifrequency optical laser signal do not overlap in frequency with any of the signals of the multifrequency optical laser signal.

Multifrequency laser having reduced wave mixing

A method of and apparatus for measuring chirp passes an input modulated optical signal through a Waveguide Grating Router (WGR) and processes the signals from adjacent WGR output ports in an oscilloscope, to obtain the real-time dynamic chirp measurements of the modulated optical signal.

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Old Bridge, NJ, United States of America

Rene Henri Monnard