Patent ID: 7245418

Claim:
An apparatus for switching a light beam comprising: an electro-optic attenuator adapted to provide controlled attenuation of the light beam, having a control input, and having ON and OFF states, one of the ON and OFF states results when either first or second control voltages are applied to the control input, where the first and second control voltages are different voltages, and the other of the ON and OFF states results when a third control voltage is applied to the control input; and a voltage generator, coupled to the control input, generates first, second and third voltages where the first and second voltages are substantially equal to the first and second control voltages, respectively, so that the one of the ON and OFF states is provided by the electro-optic attenuator while either of the first or second voltages is applied to the control input, the third voltage being substantially equal to the third control voltage where the third voltage applied to the control input causes the other of the ON and OFF states; the voltage generator generating alternating current, AC, output voltages having upper and lower peak voltages, wherein the first and second control voltages are each set to one of the upper and lower peak voltages and the third control voltage is set to the other of the upper and lower peak voltages, the first control voltage being greater than zero volts and the second control voltage being less than zero volts; the electro-optic attenuator having a half wave voltage of V π and a built-in optical bias V OB , the voltage generator having a duty cycle α selected in accordance with the equation α=(0.5/ V π )( V 90 +V OB ); the voltage generator generating an average voltage applied to the control input of the electro-optic attenuator of substantially zero volts based on satisfaction of said equation.