A method for tuning a laser via a temperature control loop that linearizes a non-linear characteristic of a thermal electric cooler (TEC) element used to adjust the temperature of tuning components and corresponding laser apparatus. One or more TEC elements are thermally coupled to respective tuning components, such as etalon filters. The TEC elements provide a heat transfer function (cooling rate) in response to a received electrical input (drive signal), wherein the relationship between the cooling rate and the drive signal is non-linear. An un-compensated drive signal produced by the control loop is compensated such that the open loop gain of the control loop is linearized via a linearizer control block. In effect, the non-linear transfer function of the TEC element is cancelled out by the linearizer control block to produce a linear relationship between the cooling rate and the drive signal. This open loop gain linearization enables tuning events such as channel slewing, and laser start-up operations to be performed with reduced tuning overshoots and undershoots that would otherwise result from the non-linear TEC transfer function characteristic.