occurs left vertical axis such that a decrease in laser power output results in a shorter operating wavelength as shown a power change from 3 0 mw to below 1 0 mw results in a wavelength shift of about 2000 picometers in modem dense wavelength division multiplex dwdm systems designed for 100 ghz or tighter channel spacings the channels are only u2212 100 picometers wide around a nominal specified center wavelength thus the change in wavelength operation that occurs with the power adjustment shown in fig2 is too large and is unacceptable for modem telecommunication systems 0032 fig3 is a chart that illustrates the effect on operating wavelength when the temperature reference voltage vtemp is adjusted for the laser transmitter 10 of fig1 while the output power of the laser transmitter and vref are kept constant the slope of the curve in fig3 is negative that is an increase in temperature reference voltage vtemp causes the tec element to operate at a cooler temperature which results in a shorter operating wavelength for the laser diode as shown a change in vtemp from 2 to 3 volts results in a wavelength shift of about 2000 picometers it has been found in the present approach that by taking into account the wavelength shift due to power adjustment and due to temperature a power control circuit can be implemented that provides variable laser power output while maintaining operation of the laser diode at a nominal wavelength within an acceptable range in an embodiment of a laser control circuit 100 in accordance with the present approach shown in fig4.