Eye diagram improving method for laser transmitter

1. A method for calibrating a laser transmitter, comprising:

(a) detecting an eye diagram of an output from the laser transmitter;

(b) determining if the eye diagram is acceptable;

(c) if the eye diagram is not acceptable, changing a value of a control signal of a limiting amplifier coupled to a laser driver in the laser transmitter, wherein the control signal controls at least one variable resistor coupled between rail and a differential pair in the limiting amplifier; and

(d) repeating steps (a), (b), and (c) until the eye diagram is acceptable.

2. The method of claim 1 , wherein the control signal sets a common-mode of a pair of differential output signals from the limiting amplifier.

3. The method of claim 1 , wherein the control signal sets a peak amplitude of a pair of differential output signals from the limiting amplifier.

4. The method of claim 1 , wherein said detecting an eye diagram comprises:

coupling the output of the laser transmitter to an oscilloscope, wherein the oscilloscope generates an eye mask margin; and

downloading the eye mask margin from the oscilloscope to a computer.

5. The method of claim 4 , wherein said determining if the eye diagram is acceptable comprises:

using the computer to determine if the eye mask margin has reached an acceptable value.

6. The method of claim 1 , wherein said changing a value of a control signal comprises:

at least one of incrementing and decrementing the value of tho control signal.