Abstract:
A channel-growth plan for an optical transmission system selects channels such that the transients that result in the channels that survive a network failure, such as an upstream fiber cut, are either minimized or effectively handled by some transient-control technique. In one embodiment, the growth plan may try to keep post-transient surviving channel total power gain equal to the pre-transient total power gain. Alternatively, the growth plan may try to distribute the surviving channels uniformly over the pre-transient channel-frequency range. Other manifestations are to keep (1) the average power of the surviving channels substantially equal to the average power of the pre-transient channels or (2) the average power of the post-transient surviving channels substantially equal to the power level of a specified channel. Transient-control can be balanced with conventional low-cost and high-performance goals to provide an effective hybrid channel-growth plan.
Abstract:
The process time required for fluorine doping of porous silica bodies to produce fluorine doped preforms for the manufacture of depressed index optical fibers is reduced by separating the doping step into a predeposit step, where "excess" fluorine is deposited on the silica particles within the porous silica body, and a drive-in step where atomic fluorine is distributed into the silica particles. The drive-in step is conveniently combined with the sintering or consolidation step to further enhance the efficiency of the doping process and is carried out at a temperature above 1300°C in an atmosphere devoid of fluorine.
Abstract:
A new type of multimode fiber is provided, capable of being constructed without the need for chemical doping. The fiber contains a core region comprising a first material and one or more axially oriented elements disposed in the first material. The axially oriented elements (which typically extend throughout the length of the fiber) are configured to provide a graded effective refractive index profile or to provide more focused interaction with selected modes. The fiber further contains a cladding region surrounding the core region, where the cladding region exhibits a refractive index less than the effective refractive index of the portion of the core immediately adjacent the cladding region, i.e., there exists an index step at the core/cladding interface.
Abstract:
In an optical transmission system, operations of certain elements are adjusted in an individualized manner after detecting a change in the total optical power level corresponding to multiple optical channels in a link of the system in order to control transients in those channels. For example, in response to a sudden drop in the number of channels resulting from a fiber cut, the power levels of the optical pumps in a Raman amplifier in an OADM are adjusted to reduce transient gain errors in the surviving channels, where the adjustment to the pump power level for each different optical pump is a function of both the detected change in the total optical power level and at least one specified coefficient for that particular optical pump, in order to handle non-linearities in the response of the Raman amplifier to the sudden drop in the number of optical channels.
Abstract:
The process time required for fluorine doping of porous silica bodies to produce fluorine doped preforms for the manufacture of depressed index optical fibers is reduced by separating the doping step into a predeposit step, where "excess" fluorine is deposited on the silica particles within the porous silica body, and a drive-in step where atomic fluorine is distributed into the silica particles. The drive-in step is conveniently combined with the sintering or consolidation step to further enhance the efficiency of the doping process and is carried out at a temperature above 1300°C in an atmosphere devoid of fluorine.
Abstract:
In an optical transmission system, operations of certain elements are adjusted in an individualized manner after detecting a change in the total optical power level corresponding to multiple optical channels in a link of the system in order to control transients in those channels. For example, in response to a sudden drop in the number of channels resulting from a fiber cut, the power levels of the optical pumps in a Raman amplifier in an OADM are adjusted to reduce transient gain errors in the surviving channels, where the adjustment to the pump power level for each different optical pump is a function of both the detected change in the total optical power level and at least one specified coefficient for that particular optical pump, in order to handle non-linearities in the response of the Raman amplifier to the sudden drop in the number of optical channels.