Laser power monitor
View Patent ↗In part, the disclosure relates to a method of controlling power output of a tunable laser. The method may include changing optical loss during a first time period; recording gain chip voltage V value changes and optical output power P value changes during the first time period; and compensating for changes in gain chip voltage and/or gain chip current, using a feedback control loop, based on the correlation between optical output power P change and gain chip voltage V change, due to optical loss changes measured during the first time period.
1 . A method of controlling power output of a tunable laser comprising:
changing optical loss during a calibration period;
recording gain chip voltage V value changes and optical output power P value changes during the calibration period; and
compensating for changes in gain chip voltage and/or gain chip current, using a feedback control loop, based on the correlation between the optical output power P changes and the gain chip voltage V changes, due to optical loss changes measured during the calibration period.
2 . The method of claim 1 , wherein the feedback control loop comprises one or more linear models, wherein each linear model comprises a coefficient determined in response to changes in optical losses of laser.
3 . The method of claim 1 , further comprising fitting P as a function of V to obtain a first coefficient.
4 . The method of claim 3 , further comprising recording gain chip current I value changes and optical output power P value changes during the calibration period.
5 . The method of claim 3 further comprising fitting P as a function of I to obtain a second coefficient.
6 . The method of claim 1 , further comprising recording gain chip current I value changes and gain chip V value changes during the calibration period.
7 . The method of claim 6 further comprising fitting V as a function of I to obtain a third coefficient.
8 . The method of claim 1 further comprising mitigating gain-chip-to-photonic integrated circuit (PIC) coupling efficiency degradation using the feedback control loop, wherein the feedback control loop includes a linear model calibrated using optical loss changes.
9 . The method of claim 1 , wherein the calibration period is a sweep period.
10 . The method of claim 1 , wherein one or more steps are performed using a microprocessor.
11 . A method of controlling power output of a tunable laser comprising:
reading an I value and a V value from a gain chip of a laser, wherein I is a current and V is a voltage;
calculating a first power value (Δ P1) based on the I value deviating from a calibration current value;
calculating a second power value (ΔP2) based on the V value deviating from a calibration voltage value;
determining a I NEW value, wherein I NEW is a new current; and
applying the I NEW on a gain chip, wherein applying the I NEW on a gain chip adjusts the power output of the tunable laser.
12 . The method of claim 11 , wherein one or more steps are performed using a microprocessor.
13 . The method of claim 11 further comprising repeating all steps during operation of the tunable laser.
14 . The method of claim 11 , wherein ΔP1=(I−Ic)×K PI , wherein Ic is the calibration current value and K PI is a first linear coefficient.
15 . The method of claim 14 , wherein ΔP2=(V−Vc)×Kpv, wherein Vc is the calibration voltage value and Kpv is a second linear coefficient.
16 . The method of claim 15 , wherein I new =I−g*(ΔP1+ΔP2), wherein g is a proportionality factor.
17 . The method of claim 15 , wherein the Ic and Vc are obtained during a calibration period.
18 . The method of claim 17 further comprising varying optical losses of tunable laser during the calibration period.