A method for compensating for ASE in gain control mode while controlling gain of an optical amplifier, the method including the following steps: (i) obtaining value for input and output power electronic circuitry DC offset; (ii) selecting the following set point values: power set point=0.0, gain set point=desired gain, (iii) obtaining digital value representing signal input value and subtracting input power electronic circuitry DC offset to produce adjusted input power value; (iv) obtaining digital value representing signal output value and subtracting output power electronic circuitry DC offset to produce adjusted output power value; (v) obtaining the ASE content of the adjusted input power value by either utilizing a lookup table or a formula and subtract ASE content from the adjusted input power value to produce ASE adjusted output power value; (vi) either multiplying the gain setpoint by the obtained ASE adjusted input power value and subtracting this from the ASE adjusted output power value, or dividing the ASE adjusted input power to obtain gain control error signal; (vii) subtracting the gain control error signal from any number to produce a controller input signal; (viii) transforming the controller input signal into digital representation of at least one pump control signal by a control algorithm; (xi) transforming said digital representation of said at least one pump control signal into at least one corresponding analog pump control signal; and (x) applying the at least one analog pump control signal to at least one pump via driver circuitry.