Method And Apparatus For Optical Transmission In A Communication Network
A manner of mitigating the self heating effect of a laser or other light source such as a laser in a network node of a communication network. A self-heating mitigation module is provided, the self-heating mitigation module includes one or both of a self-heating adjustment module to accelerate self heating at the beginning of a transmission and a sub-threshold lasing module that applies a sub-threshold current between transmissions. The self-heating adjustment module and the sub-threshold lasing module are preferable both used together and driven by a common signal, for example the burst_enable signal that facilitates transmission from the light source.
1 . A network node, comprising
a laser light source; and
circuitry for driving the laser light source, wherein the circuitry comprises a self-heating mitigation module.
2 . The network node of claim 1 , further comprising:
a processor for controlling operation of components of the network node; and
a memory device for storing executable program instructions.
3 . The network node of claim 2 , further comprising executable program instructions stored on the memory device that when executed cause the network node to form a transmission preamble initially dominated by 1 bits.
4 . The network node of claim 3 , wherein the formed preamble gradually assumes a bit pattern comprising alternating 1 bits and 0 bits.
5 . The network node of claim 1 , wherein the self-heating mitigation module comprises a sub-threshold lasing module configured to selectively apply a sub-threshold a sub-threshold current to the laser light source.
6 . The network node of claim 5 , wherein the sub-threshold lasing module is controlled by a burst_enable signal generated in the network node.
7 . The network node of claim 1 , wherein the self-heating mitigation module comprises a self-heating adjustment module configure to accelerate the self-heating of the laser light source.
8 . The network node of claim 7 , wherein the self-heating adjustment module comprises an RC circuit configured for producing an overshoot of laser bias current at the beginning of a transmission.
9 . The network node of claim 6 , wherein the self-heating adjustment module is controlled by a burst_enable signal generated in the network node.
10 . A method operating a network node comprising a laser light source, the method comprising accelerating self heating of the laser light source at the beginning of a transmission.
11 . The method of claim 10 , wherein accelerating self heating of the laser light source comprises forming a transmission preamble initially dominated by 1 bits.
12 . The method of claim 10 , wherein accelerating self heating of the laser light source comprises applying an overshoot of the laser current at the beginning of a transmission.
13 . The method of claim 12 , wherein the applying an overshoot of the laser current is controlled by a burst_enable signal.
14 . The method of claim 10 , further comprises selectively applying a sub-threshold lasing current to the laser light source.
15 . The method of claim 14 , wherein the sub-threshold lasing current is only applied when the laser light source is in a non-transmitting state.
16 . The method of claim 14 , wherein the sub-threshold lasing current application is controlled by a burst_enable signal.
17 . The method of claim 14 , further comprising deactivating application of the sub-threshold lasing current when the laser light source is not operated for extended periods.