Out of band communications link for 4-lane optical modules using dark fibers and low-bandwidth LEDs

1. A module comprising:

a first transmitter configured to transmit user data through a first physical channel of a connector;

a first detector configured to receive a first status signal but not receive said user data through a second physical channel of said connector;

a second transmitter configured to transmit an initialization pattern but not transmit said user data through a third physical channel of said connector; and

a controller configured to (i) send said initialization pattern to said second transmitter and (ii) adjust a power of said first transmitter in response to said first status signal such that (a) said first transmitter is an off mode until said first status signal indicates that said initialization pattern has been seen at an opposite end of said third physical channel, (b) said first transmitter is in a low power mode until said first status signal indicates that said first transmitter can be seen at an opposite end of said first physical channel and (c) said first transmitter is in a normal power mode thereafter.

2. The module according to claim 1 , wherein said second physical channel comprises a multi-mode optical fiber.

3. The module according to claim 2 , wherein said first transmitter comprises a non-eye-safe laser.

4. The module according to claim 3 , wherein said first detector is configured to detect visible signals and said second transmitter is configured to generate visible signals.

5. The module according to claim 1 , further comprising a second detector coupled to said controller and configured to receive said user data through a fourth physical channel of said connector.

6. The module according to claim 5 , wherein said controller is further configured to provide a second status signal to said second transmitter in response to said user data as received in both said first physical channel and said fourth physical channel.

7. The module according to claim 6 , wherein said second transmitter produces a non-coherent light.

8. The module according to claim 1 , wherein (i) a laser driver circuit of said first transmitter is configured to provide a power utilization signal to said controller and (ii) said controller is further configured to adjust said power of said first transmitter in response to said power utilization signal.

9. The module according to claim 1 , wherein (i) said connector is configured per a standard defining an unused physical channel and (ii) second physical channel is said unused physical channel.

10. The module according to claim 9 , wherein said standard defines at least two unused physical channels that are used by said module.

11. A method of operating a communications link, comprising the steps of:

(A) transmitting a first user data through a first physical channel in a connector of said communications link;

(B) receiving a first status signal but not receiving a second user data through a second physical channel in said connector of said communications link;

(C) transmitting an initialization pattern but not transmitting said first user data through a third physical channel in said connector of said communications link; and

(D) adjusting a transmission power for said first physical channel in response to said first status signal such that (a) said first physical channel is dark until said first status signal indicates that said initialization pattern has been seen at an opposite end of said third physical channel, (b) said first physical channel carries low power light until said first status signal indicates that said low power light can be seen at an opposite end of said first physical channel and (c) said first physical channel carries normal power light thereafter.

12. The method according to claim 11 , further comprising the step of receiving said second user data through a fourth physical channel of said communications link.

13. The method according to claim 12 , further comprising the step of transmitting a second status signal through said third physical channel of said communications link in response to said second user data.

14. The method according to claim 13 , further comprising the step of receiving a third user data through a fifth physical channel of said communications link.

15. The method according to claim 14 , further comprising the step of transmitting said second status signal in response to both said second user data and said third user data.

16. The method according to claim 11 , wherein said initialization pattern is an optical pattern noticeable to a human observer.

17. The method according to claim 16 , further comprising the step of modulating said first status signal to flash in a fault pattern (i) different than said initialization pattern and (ii) noticeable to said human observer in response to a failed condition in a transmitter module of said communication link.

18. The method according to claim 16 , further comprising the steps of:

disabling transmission through said first physical channel in response to an absence of said first status signal; and

transmitting said initialization pattern after said disabling.

19. The method according to claim 11 , wherein said first status signal is transmitted at least three orders of magnitude slower than said first user data.

20. A module comprising:

means for transmitting user data through a first physical channel in a connector of a communications link;

means for receiving a first status signal but not receiving said user data through a second physical channel in said connector of said communications link;

means for transmitting an initialization pattern but not said user data through a third physical channel in said connector of said communications link; and

means for adjusting a transmission power for said first physical channel in response to said first status signal such that (a) said first physical channel is dark until said first status signal indicates that said initialization pattern has been seen at an opposite end of said third physical channel, (b) said first physical channel carries low power light until said first status signal indicates that said low power light can be seen at an opposite end of said first physical channel and (c) said first physical channel carries normal power light thereafter.