A control circuit for a tunable laser has a logic circuit configured to generate a plurality of digital control signals using a table of calibration parameters stored in that circuit. The logic circuit receives an input signal specifying, e.g., an optical communication channel, retrieves the corresponding parameter values from the table of calibration parameters, and generates the digital control signals that are digital-to-analog converted, amplified, and applied to the tunable laser. The table of calibration parameters may be custom-generated for each particular tunable laser to accommodate laser-to-laser variations. In addition, the table of calibration parameters may be periodically updated to correct for wavelength drifting due to laser aging. A control circuit of the invention can be configured to update the table of calibration parameters in a non-disruptive continuous manner while the tunable laser controlled by the circuit is used for data transmission. Certain control circuits of the invention can support channel-to-channel switching times on the order of 50 ns.