Optical mean power controller with provisionable output levels
First Claim
1. An optical signal generator comprising;
- a light source for generating an optical signal;
an optical power-adjusting apparatus for adjusting the optical power-level of the optical signal before it exits the generator;
an optical power-monitoring apparatus for monitoring the actual power-level of the optical signal outputted by the optical power-adjusting apparatus and generating from said power-level a related present-level signal;
a comparator for comparing the present-level signal to a reference signal in order to supply a control signal to the optical power-adjusting apparatus that causes the present-level signal to be set equal to the reference signal; and
an optical power-setting apparatus for generating the reference signal for use by the comparator, such that the comparator causes the optical power-adjusting apparatus to adjust the power-level of the optical signal to equal a user-defined power-level, wherein the optical power-setting apparatus comprises;
a digital controller for receiving user-defined power levels;
a storage means connected to the digital controller, and containing a table that maps values specifying user-defined power levels to values specifying the reference signal needed to realize said user-defined power levels; and
at least one digital to analogue signal converter (DAC) connected to the storage means for converting the values specifying the reference signal into reference signals.
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Accused Products
Abstract
A mean optical power controller that controls power using a voltage controlled optical attenuator (VCOA) is disclosed. This controller uses a control loop in which a signal indicative of the present optical power level is compared to a signal indicative of the desired optical power level, with the difference then being used as input into the VCOA. This controller generates the required variety of signals indicative of the desired optical power level, or reference signals, without having to rely on a CPU. It does this by storing in a local storage means the voltage-values of the reference signals required to realize each supported user-defined optical power level. During the operation of the controller, the voltage-value corresponding to each selected power-level is passed to one or more DACs, where it is converted into a reference signal. A plurality of DACs can be used, which each convert a fraction of each voltage-value, so as to implement a logarithmic relation between the user-defined power levels and the voltage-values. This provides fine control over the optical power level, over a sufficiently large range of values.
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Citations
20 Claims
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1. An optical signal generator comprising;
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a light source for generating an optical signal; an optical power-adjusting apparatus for adjusting the optical power-level of the optical signal before it exits the generator; an optical power-monitoring apparatus for monitoring the actual power-level of the optical signal outputted by the optical power-adjusting apparatus and generating from said power-level a related present-level signal; a comparator for comparing the present-level signal to a reference signal in order to supply a control signal to the optical power-adjusting apparatus that causes the present-level signal to be set equal to the reference signal; and an optical power-setting apparatus for generating the reference signal for use by the comparator, such that the comparator causes the optical power-adjusting apparatus to adjust the power-level of the optical signal to equal a user-defined power-level, wherein the optical power-setting apparatus comprises; a digital controller for receiving user-defined power levels; a storage means connected to the digital controller, and containing a table that maps values specifying user-defined power levels to values specifying the reference signal needed to realize said user-defined power levels; and at least one digital to analogue signal converter (DAC) connected to the storage means for converting the values specifying the reference signal into reference signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An optical signal generator comprising:
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a laser diode driven by a voltage controlled current injector; a voltage controlled optical attenuator for adjusting the optical power-level of the optical signal before it exits the generator; a PIN diode and a transimpedance amplifier for monitoring the actual power-level of the optical signal outputted by the voltage controlled optical attenuator, and for generating from said power-level a related present-level signal; an operational amplifier, and a capacitor that is connected across the inverting input and the output of the operational amplifier, for comparing the present-level signal to a reference signal in order to supply a control signal to the voltage controlled optical attenuator that causes the present-level signal to be set equal to the reference signal; a digital controller for receiving user-defined power levels; a storage means connected to the digital controller, and containing a table that maps values specifying user-defined power levels to values specifying the reference signal needed to realize said user-defined power levels; and
,a digital to analogue signal converter (DAC) connected to the storage means for converting the values specifying the reference signal into reference signals. - View Dependent Claims (18, 19)
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20. An optical signal generator comprising:
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a laser diode for generating an optical signal; a voltage controlled current injector driving the laser diode and having an input which is varied such that the optical signal generated by the laser diode is wavelength locked; an optical power adjusting apparatus for adjusting the optical power-level of the optical signal before it exits the generator; an optical power-monitoring apparatus for monitoring the actual power-level of the optical signal outputted by the optical power-adjusting apparatus and generating from said power-level a related present-level signal; a comparator for comparing the present-level signal to a reference signal in order to supply a control signal to the optical power-adjusting apparatus that causes the present-level signal to be set equal to the reference signal; and an optical power-setting apparatus for generating the reference signal for use by the comparator, such that the comparator causes the optical power-adjusting apparatus to adjust the power-level of the optical signal to equal a user-defined power-level.
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Specification