Thermal chirp compensation in a chirp managed laser
View Patent ↗Thermal chirp compensation in a chirp managed laser. In one example embodiment, a method for thermal chirp compensation in a chirp managed laser (CML) includes several acts. First, a first bias condition and temperature is selected. Next, a first thermal chirp compensation signal is generated. Then, the laser is driven by biasing a first input drive signal with the first thermal chirp compensation signal. Next, a second bias condition and temperature is selected. Then, a second thermal chirp compensation signal is generated. Finally, the laser is driven by biasing a second input drive signal with the second thermal chirp compensation signal.
1. A method for thermal chirp compensation in a chirp managed laser (CML), the method comprising:
selecting a first bias condition and temperature;
generating a first thermal chirp compensation signal corresponding to a predetermined level of thermal chirp that is induced in a laser by operating the laser at the first bias condition and temperature;
driving the laser by biasing a first input drive signal with the first thermal chirp compensation signal;
selecting a second bias condition and temperature;
generating a second thermal chirp compensation signal corresponding to a predetermined level of thermal chirp that is induced in the laser by operating the laser at the second bias condition and temperature; and
driving the laser by biasing a second input drive signal with the second thermal chirp compensation signal.
2. The method as recited in claim 1 , wherein generating a first thermal chirp compensation signal corresponding to a predetermined level of thermal chirp that is induced in the laser by operating the laser at the first bias condition and temperature comprises solving the following formula for the first compensation signal S comp :
S comp *H ( t )+ S input drive ( t )* H ( t )= S output drive ( t )
where:
H(t) is a transform function of the predetermined level of thermal chirp that is induced in the laser by operating the laser at the first bias condition and temperature;
S input drive (t) is the first input drive signal;
S output drive (t) is a compensated first input drive signal; and
* is a convolution operator.
3. The method as recited in claim 2 , wherein H(t) is calculated by de-convolving S input drive (t) and an output signal of the laser that is driven without compensation.
4. The method as recited in claim 2 , wherein H(t) is calculated using a fast Fourier transform (FFT).
5. The method as recited in claim 2 , wherein the laser comprises a distributed feedback (DFB) laser or a distributed Bragg reflector (DBR) laser.
6. The method as recited in claim 3 , wherein the laser is packaged in a transmitter optical sub assembly (TOSA).
7. The method as recited in claim 3 , wherein the laser is packaged in a transmitter 13 pin-general purpose output (GPO) butterfly transmitter package.