# US 9,519,162 B2 · Optical modulator having a plurality of modulator segments > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,519,162 B2 - Document ID: US9519162B2 - Status: Granted - Kind: B2 - Application number: 14/879,149 - Filed: 2015-10-09 - Published: 2016-04-14 - Granted: 2016-12-13 - Earliest claimed: 2014-10-09 - Assignees: Coriant Advanced Technology, LLC - Applicants: Coriant Advanced Technology, LLC - Inventors: Ran Ding; Thomas Wetteland Baehr-Jones; Peter D. Magill; Michael J. Hochberg; Alexander Rylyakov - Web page: https://patentgrep.com/patent/US9519162B2 ## CPC - G02F 1/0121: {Operation of devices; Circuit arrangements, not otherwise provided for in this subclass} - G02F 1/011: {in optical waveguides, not otherwise provided for in this subclass} - G02F 1/025: in an optical waveguide structure (G02F1/017, {G02F1/2257} take precedence) - G02F 1/035: in an optical waveguide structure - G02F 1/225: in an optical waveguide structure - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS ## Abstract An optical modulator apparatus may include a plurality of segment drivers, each segment driver having a unique offset voltage and driving but a portion or a segment of an electro-optical modulator. A modulating electrical signal may be applied to the segment drivers via a plurality of electrical delays. Parameters of the segment drivers may be selected so as to approximate a pre-defined transfer function, which may include a linear or a non-linear transfer function. ## Claims ### Claim 1 A modulator apparatus comprising: an optical path comprising an optical input port receiving an optical carrier wave, an optical output port outputting a modulated optical signal, and a succession of serially optically coupled optical modulator segments extending between the input and output optical ports modulating the optical carrier wave so as to obtain the modulated optical signal; a plurality of segment drivers, wherein each segment driver has associated: a low voltage Vlow; a high voltage Vhigh; a unique offset voltage Vos; and a threshold voltage Vth; wherein each segment driver is electrically coupled to one of the succession of the modulator segments applies a driving voltage Vd thereto in response to a control voltage Vc, such that: Vd=Vlow when VcVos+Vth; and Vdvaries between Vlow and Vhigh when Vc varies between Vos−Vth and Vos+Vth; an electrical input port receiving an electrical signal to be modulated onto the optical carrier wave to obtain the modulated optical signal; a plurality of electrical connections between the electrical input port and each segment driver. ### Claim 2 (depends on 1) The modulator apparatus of claim 1, wherein each segment driver comprises a limiting amplifier having the corresponding low voltage Vlow, the high voltage Vhigh, the unique offset voltage Vos, and the threshold voltage Vth. ### Claim 3 (depends on 2) The modulator apparatus of claim 2, wherein each electrical connection has a corresponding delay ΔTelectrical between the electrical input port and each limiting amplifier; and wherein the delays ΔTelectrical are such that in operation, the application of the driving voltage Vd to individual optical modulator segments in the succession of optical modulator segments is substantially synchronized with propagation of the optical carrier wave therein. ### Claim 4 (depends on 1) The modulator apparatus of claim 1, further comprising a comparator module operationally coupled to the electrical input port and the plurality of segment drivers to provide individual control signals to the plurality of segment drivers when the control voltage Vc exceeds the offset voltages Vos of corresponding segment drivers of the plurality of segment drivers. ### Claim 5 (depends on 1) The modulator apparatus of claim 1, wherein the succession of serially optically coupled optical modulator segments comprises an optical waveguide and a succession of electrodes disposed along the optical waveguide and operationally coupled thereto. ### Claim 6 (depends on 1) The modulator apparatus of claim 1, wherein the plurality of electrical connections comprise a succession of serially electrically coupled electrical delay line segments, wherein each progressive one of the succession of electrical delay line segments is electrically coupled to a segment driver of the plurality of segment drivers, and wherein the segment driver is electrically coupled to a corresponding progressive one of the succession of optical modulator segments. ### Claim 7 (depends on 6) The modulator apparatus of claim 6, comprising more than eight optical modulator segments and more than eight segment drivers. ### Claim 8 (depends on 1) The modulator apparatus of claim 1, wherein the offset voltage Vos of each successive segment driver is greater than the offset voltage Vos of the immediately preceding segment driver, if any. ### Claim 9 (depends on 8) The modulator apparatus of claim 8, wherein the offset voltage Vos of each successive segment driver is greater than the offset voltage Vos of the immediately preceding segment driver, if any, by a same step voltage ΔVos. ### Claim 10 (depends on 1) The modulator apparatus of claim 1, wherein a slope of each segment driver, defined as (V high−Vlow)/2Vth, is such that in operation, a degree of modulation of the modulated optical signal is substantially proportional to a magnitude of the electrical signal received at the electrical input port. ### Claim 11 (depends on 10) The modulator apparatus of claim 10, wherein the slope is less than 5. ### Claim 12 (depends on 1) The modulator apparatus of claim 1, wherein in operation, each segment driver has a delay ΔTamp between application of the control voltage Vc thereto and generation of the corresponding driving voltage Vd thereby, wherein the delays ΔTamp of at least two of the plurality of segment drivers are substantially different from one another. ### Claim 13 (depends on 1) The modulator apparatus of claim 1, wherein at least one of the low voltage Vlow,the high voltage Vhigh, and the threshold voltage V.sub.th, of at least one segment driver of the plurality of segment drivers is substantially different from a corresponding one of the low voltage Vlow, the high voltage Vhigh, and the threshold voltage V.sub.th of another segment driver of the plurality of segment drivers. ### Claim 14 (depends on 5) The modulator apparatus of claim 5, further comprising a silicon photonic chip comprising the optical waveguide. ### Claim 15 (depends on 14) The modulator apparatus of claim 14, wherein the silicon photonic chip comprises the plurality of segment drivers. ### Claim 16 (depends on 1) The modulator apparatus of claim 1, wherein the low voltage Vlow, the high voltage Vhigh, and the threshold voltage Vth of each segment driver of the plurality of segment drivers are such that a degree of modulation of the modulated optical signal is a function of the electrical signal received by the electrical input port; wherein the function is selected from the list consisting of quadratic, cubic, periodic, or an exponential function. ### Claim 17 A method of modulating an optical carrier wave by an electrical signal, the method comprising: propagating the optical carrier wave in a succession of serially optically coupled optical modulator segments; and coupling the electrical signal to a plurality of segment drivers, wherein each segment driver has associated: a low voltage Vlow; a high voltage high; a unique offset voltage Vos; and a threshold voltage Vth, wherein each segment driver is electrically coupled to one of the succession of the modulator segments for applying a driving voltage Vd thereto in response to a control voltage Vc, such that: Vd=Vlow when VcVos+Vth; and Vd varies between Vlow and Vhigh when Vc varies between Vos−Vth and Vos+Vth. ### Claim 18 (depends on 17) The method of claim 17, wherein the electrical signal is coupled to an electrical input port, from which the electrical signal propagates to each segment driver via a plurality of electrical connections between an electrical input port and each segment driver; wherein each electrical connection has a corresponding delay ΔTelectrical between the electrical input port and each segment driver; and wherein the delays ΔTelectrical are such that the application of the driving voltage Vd to individual optical modulator segments in the succession of optical modulator segments is substantially synchronized with propagation of the optical carrier wave therein. ### Claim 19 (depends on 17) The method of claim 17, further comprising pre-selecting the offset voltage Vos of each successive segment driver to be greater than the offset voltage Vos of the immediately preceding segment driver, if any. ### Claim 20 (depends on 19) The method of claim 19, further comprising pre-selecting the low voltage Vlow, the high voltage Vhigh, the offset voltage Vos, and the threshold voltage Vth of each segment driver of the plurality of segment drivers such that Vlow of each successive segment driver is substantially equal to Vhigh of the immediately preceding segment driver, if any. ### Claim 21 (depends on 19) The method of claim 19, further comprising pre-selecting a slope of each segment driver, defined as (Vhigh−Vlow)/2Vth, so as to provide a degree of modulation of the optical carrier wave substantially proportional to a magnitude of the electrical signal received at the electrical input port. ### Claim 22 A modulator apparatus comprising: an optical path comprising an optical input port receiving an optical carrier wave, an optical output port outputting a modulated optical signal, and a plurality of serially optically coupled optical modulator segments extending between the input and output optical ports and modulating the optical carrier wave so as to obtain the modulated optical signal; an electrical input port receiving an electrical signal to be modulated onto the optical carrier wave to obtain the modulated optical signal; an analog to digital converter operationally coupled to the electrical input port, digitizing the electrical signal to provide a plurality of input digital signals; a digital filter operationally coupled to the analog to digital converter, and receiving and digital filtering the plurality of input digital signals to provide a plurality of output digital signals, each of which for driving one of the plurality of optical modulator segments. ### Claim 23 (depends on 22) The modulator apparatus of claim 22, wherein the digital filter is configured to provide an amplitude pre-emphasis to lessen a non-linearity of modulation of the optical carrier wave by the electrical signal. ### Claim 24 (depends on 22) The modulator apparatus of claim 22, wherein the digital filter is configured to provide a pre-determined frequency response. ### Claim 25 (depends on 22) The modulator apparatus of claim 22, further comprising a photodetector optically coupled to the optical output port to provide a feedback signal; and a controller operationally coupled to the photodetector and the digital filter to receive the feedback signal from the photodetector and provide a control signal to the digital filter in dependence on the feedback signal.