Abstract: The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Tunable lasers are employed to generate respective subcarrier frequencies which represent subchannels of an ITU channel to which client signals can be mapped. In one embodiment, subchannels are polarization interleaved to reduce crosstalk. In another embodiment, polarization multiplexing is used to increase the spectral density. Client circuits can be divided and combined with one another before being mapped, independent of one another, to individual subchannels within and across ITU channels. A crosspoint switch can be used to control the client to subchannel mapping, thereby enabling subchannel protection switching and hitless wavelength switching.

Abstract: The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Tunable lasers are employed to generate respective subcarrier frequencies which represent subchannels of an ITU channel to which client signals can be mapped. In one embodiment, subchannels are polarization interleaved to reduce crosstalk. In another embodiment, polarization multiplexing is used to increase the spectral density. Client circuits can be divided and combined with one another before being mapped, independent of one another, to individual subchannels within and across ITU channels. A crosspoint switch can be used to control the client to subchannel mapping, thereby enabling subchannel protection switching and hitless wavelength switching.

Abstract: The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Various wavelocker apparatus and methods are disclosed that measure the frequency offsets between signal lasers and reference lasers. The measured offsets are used to adjust the signal laser frequencies to meet their target frequencies. The absolute accuracy of the reference laser frequency is improved by measuring the absorption of the reference laser by a gas cell with known fixed absorption lines versus the reference laser frequency. Apparatus and methods are disclosed to cover scenarios in which the reference laser polarization is aligned with the signal lasers, as well as those in which the reference laser polarization is not aligned with the signal lasers. The wavelocker apparatus may or may not be located at the same network site as the signal lasers.

Abstract: Gain for single and multi-stage optical amplifiers is controlled to determine gain profile and adjust for input signal transients by varying the gain linearly in relation to balanced variable gain settings in input signal and output signal feedback circuits. ASE correction may be dynamically applied in relation to temperature, input signal level, and gain setting. Feed-forward transient control may also be applied.

Abstract: An optical fiber connector is used as a means of carrying an optical element. The optical element is either permanently or removeably affixed to a planar end of the optical fiber connector with a suitable adhesive or gel. After the mating connector plugs are secured together, the affixed optical element is adjacent each end of each connector plug becoming in-line with the connector.

Abstract: By using a pumped erbium doped fibre (EDF) cascaded with a non-saturable absorbing fibre (NSAF), an amplifier is provided with a desired flat uniform output response for a input signals with different intensities at a plurality of wavelengths. Furthermore, from a commercial standpoint, the amplifier is relatively inexpensive and simple to fabricate, being compatible with standard telecommunication fibre. With this particular invention, a previously recognized undesired characteristic of NSAF, its poor amplification qualities, are now being used to an advantage.

Abstract: The subject of the invention is a device synchronizing modes of the laser, fastened in its resonance cavity, in a housing 1 having its inner temperature stabilized, which contains an acousto-optical modulator whose buffer 5, functioning at the same time as a prism, together with a transducer 13 generating an acoustic wave for modulation of a light wave and with a back mirror 11 form an integrated optical element in the form of a prism with a trapezoid base.