HIGHER ORDER OPTICAL PAM MODULATION USING A MACH-ZEHNDER INTERFEROMETER (MZI) TYPE OPTICAL MODULATOR HAVING A BENT OPTICAL PATH
First Claim
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1. An optical modulator, comprising:
- an optical waveguide having an input and an output;
a plurality of PN junction phase shifters, each PN junction phase shifter extending along a portion of said optical waveguide;
a digital to analog converter configured to receive an n-bit input digital signal and output a pulse amplitude modulated (PAM) analog signal having 2n levels, where n is greater than or equal to 2; and
a drive circuit having an input configured to receive said analog signal, said drive circuit comprising a plurality of drivers coupled in cascade, each driver configured to generate a drive signal in response to said PAM analog signal for controlling operation of a corresponding PN junction phase shifter.
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Abstract
An optical modulator includes an optical waveguide including at least a first PN junction phase shifter and a second PN junction phase shifter. A driver circuit drives operation of the first and second PN junction phase shifters in response to a pulse amplitude modulated (PAM) analog signal having 2n levels. The PAM analog signal is generated by a digital to analog converter that receives an n-bit input signal. In an implementation, the optical waveguide and PN junction phase shifters are formed on a first integrated circuit chip and the driver circuit is formed on a second integrated circuit chip that is stacked on and electrically connected to the first integrated circuit chip.
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Citations
25 Claims
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1. An optical modulator, comprising:
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an optical waveguide having an input and an output; a plurality of PN junction phase shifters, each PN junction phase shifter extending along a portion of said optical waveguide; a digital to analog converter configured to receive an n-bit input digital signal and output a pulse amplitude modulated (PAM) analog signal having 2n levels, where n is greater than or equal to 2; and a drive circuit having an input configured to receive said analog signal, said drive circuit comprising a plurality of drivers coupled in cascade, each driver configured to generate a drive signal in response to said PAM analog signal for controlling operation of a corresponding PN junction phase shifter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method, comprising:
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receiving an n-bit input digital signal; converting the n-bit input digital signal to a pulse amplitude modulated (PAM) analog signal having 2n levels, where n is greater than or equal to 2; generating from said PAM analog signal a plurality of drive signals; and applying each drive signal to PN junction phase shifter of an optical waveguide, each PN junction phase shifter extending along a portion of said optical waveguide. - View Dependent Claims (15, 16, 17, 18, 19)
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20. An optical modulator, comprising:
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an optical waveguide having; an input waveguide; and an optical splitter to split the input waveguide into a first waveguide arm and a second waveguide arm, said first and second waveguide arms being parallel to each other; a first PN junction phase shifter positioned on the first waveguide arm; a second PN junction phase shifter positioned on the first waveguide arm; a third PN junction phase shifter positioned on the second waveguide arm parallel to the first PN junction phase shifter; a fourth PN junction phase shifter positioned on the second waveguide arm parallel to the third PN junction phase shifter; a digital to analog converter configured to receive an n-bit input digital signal and output a pulse amplitude modulated (PAM) analog signal having 2n levels, where n is greater than or equal to 2; a first driver having an input configured to receive the PAM analog signal and an output configured to generate first drive signals for application to control operation of the first and second PN junction phase shifters; and a second driver having an input configured to receive the first drive signals and an output configured to generate second drive signals for application to control operation of the third and fourth PN junction phase shifters. - View Dependent Claims (21, 22, 23, 24, 25)
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Specification