Abstract: A modulator may include a substrate. The modulator may include one or more waveguides formed upon or formed in the substrate. A signal electrode may be provided adjacent to at least one of the one or more waveguides and may include a curved outer surface. The modulator may include one or more ground electrodes provided adjacent to the signal electrode. Each ground electrode, of the one or more ground electrodes, may include a respective curved inner surface that is radially spaced from the curved outer surface of the signal electrode. The one or more ground electrodes and the substrate may at least substantially enclose the curved outer surface of the signal electrode.

Abstract: A modulator may include a substrate. The modulator may include one or more waveguides formed upon or formed in the substrate. A signal electrode may be provided adjacent to at least one of the one or more waveguides and may include a curved outer surface. The modulator may include one or more ground electrodes provided adjacent to the signal electrode. Each ground electrode, of the one or more ground electrodes, may include a respective curved inner surface that is radially spaced from the curved outer surface of the signal electrode. The one or more ground electrodes and the substrate may at least substantially enclose the curved outer surface of the signal electrode.

Abstract: A modulator may include a substrate. The modulator may include one or more waveguides formed upon or formed in the substrate. A signal electrode may be provided adjacent to at least one of the one or more waveguides and may include a curved outer surface. The modulator may include one or more ground electrodes provided adjacent to the signal electrode. Each ground electrode, of the one or more ground electrodes, may include a respective curved inner surface that is radially spaced from the curved outer surface of the signal electrode. The one or more ground electrodes and the substrate may at least substantially enclose the curved outer surface of the signal electrode.

Abstract: A modulator may include a substrate. The modulator may include one or more waveguides formed upon or formed in the substrate. A signal electrode may be provided adjacent to at least one of the one or more waveguides and may include a curved outer surface. The modulator may include one or more ground electrodes provided adjacent to the signal electrode. Each ground electrode, of the one or more ground electrodes, may include a respective curved inner surface that is radially spaced from the curved outer surface of the signal electrode. The one or more ground electrodes and the substrate may at least substantially enclose the curved outer surface of the signal electrode.

Abstract: The invention relates to waveguide optical modulators wherein two or more waveguides are modulated with specific modulation strengths using a single straight signal electrode or a single multi-segment signal electrode. Modulation strengths for each of a plurality of waveguides modulated by a single multi-segment electrode are matched over a wide modulation frequency range. Linearized output characteristics with respect to second and third order distortions arc achieved in one aspect of the invention.

Abstract: An electrical termination circuit for a traveling wave optoelectronic device is disclosed. The electrical termination circuit is constructed to reflect a portion of a radio-frequency signal back into the optoelectronic device. The reflected signal is out of phase with the applied radio-frequency signal at a frequency of a detrimental spectral feature or a bump in an electro-optical transfer characteristic of the optoelectronic device. The amplitude and the phase of the reflected signal are selected so as to suppress the detrimental spectral feature without a significant reduction in the efficiency of electro-optical or optical-electrical transformation of the optoelectronic device.

Abstract: A method of controlling the operating parameters of an optical modulator, without using a dither signal, is provided. Past operating parameters are compared to present operating parameters using a quality of modulation signal obtained by cross-correlating the data modulation signal used to drive the optical modulator with the modulated optical signal output from the optical modulator. The quality of modulation signal is used to optimize the operating parameters (e.g., bias point) of the optical modulator, or other operating parameters of the arrangement, such as the modulator drive level, timing alignment, etc.

Abstract: The invention relates to an optical waveguide device that includes a waveguide phase modulator (WPM). A waveguide monitoring structure is coupled optically in parallel with the WPM so as to form a Mach-Zehnder interferometer therewith for producing monitor light indicative of a phase shift imparted by the WPM. The waveguide monitoring structure includes a first optical tap for tapping off a fraction of light entering the first WPM for providing first tapped-off light, a second optical tap for tapping off a fraction of light exiting the first WPM for providing second tapped off light, and an ancillary phase modulator for modulating the optical phase of the first or second tapped-off light so as to modulate the intensity of the monitor light in dependence upon the first phase shift. A feedback circuit controls the phase shift imparted by the WPM based on a modulation index of the monitor light.

Abstract: The invention relates to waveguide optical modulators wherein two or more waveguides are modulated with specific modulation strengths using a single straight signal electrode or a single multi-segment signal electrode. Modulation strengths for each of a plurality of waveguides modulated by a single multi-segment electrode are matched over a wide modulation frequency range. Linearized output characteristics with respect to second and third order distortions arc achieved in one aspect of the invention.

Abstract: An electrical termination circuit for a traveling wave optoelectronic device is disclosed. The electrical termination circuit is constructed to reflect a portion of a radio-frequency signal back into the optoelectronic device. The reflected signal is out of phase with the applied radio-frequency signal at a frequency of a detrimental spectral feature or a bump in an electro-optical transfer characteristic of the optoelectronic device. The amplitude and the phase of the reflected signal are selected so as to suppress the detrimental spectral feature without a significant reduction in the efficiency of electro-optical or optical-electrical transformation of the optoelectronic device.

Abstract: A Mach-Zehnder (MZ) interferometer modulator structure for fiberoptic telecommunications is disclosed in which drift of the operating point can be monitored with a reduced phase tracking error. One or more components of free-space light radiated into the substrate of the MZ modulator are selectively detected with one or more photodetectors. Suitable summing circuits are described for nulling out undesired photocurrent contributions in the photodetector(s) from on-state and off-state light radiated from the MZ.

Abstract: The invention relates to an external optical modulator comprising a Mach-Zehnder having a signal electrode including at least four sections of unequal length to one another positioned over an alternating domain structure in an electrooptic substrate, and including a center section, or center pair of sections disposed asymmetrically between pairs surrounding sections. The surrounding pairs, comprise the two sections adjacent the center section or pair of sections, and each two sections adjacent the previous pair of sections, moving outwardly from the center to the final outermost pair, L1 and LN at the RF input 2 and RF output 4. In each pair, the section lengths are equal, or the section closer to the RF output 4 has a longer length than the section closer to the RF input 2. The surrounding pairs have lengths that decrease from the innermost pair to the outermost pair. For a zero chirp structure, the section lengths are selected to maintain an equivalent length for the inverted and uninverted domain sections.

Abstract: A method of controlling the operating parameters of an optical modulator, without using a dither signal, is provided. Past operating parameters are compared to present operating parameters using a quality of modulation signal obtained by cross-correlating the data modulation signal used to drive the optical modulator with the modulated optical signal output from the optical modulator. The quality of modulation signal is used to optimize the operating parameters (e.g., bias point) of the optical modulator, or other operating parameters of the arrangement, such as the modulator drive level, timing alignment, etc.

Abstract: A Mach-Zehnder (MZ) interferometer modulator structure for fiberoptic telecommunications is disclosed in which drift of the operating point can be monitored with a reduced phase tracking error. One or more components of free-space light radiated into the substrate of the MZ modulator are selectively detected with one or more photodetectors. Suitable summing circuits are described for nulling out undesired photocurrent contributions in the photodetector(s) from on-state and off-state light radiated from the MZ.

Abstract: The invention relates to an optical waveguide device that includes a waveguide phase modulator (WPM). A waveguide monitoring structure is coupled optically in parallel with the WPM so as to form a Mach-Zehnder interferometer therewith for producing monitor light indicative of a phase shift imparted by the WPM. The waveguide monitoring structure includes a first optical tap for tapping off a fraction of light entering the first WPM for providing first tapped-off light, a second optical tap for tapping off a fraction of light exiting the first WPM for providing second tapped off light, and an ancillary phase modulator for modulating the optical phase of the first or second tapped-off light so as to modulate the intensity of the monitor light in dependence upon the first phase shift. A feedback circuit controls the phase shift imparted by the WPM based on a modulation index of the monitor light.

Abstract: The invention relates to an external optical modulator comprising a Mach-Zehnder having a signal electrode including at least four sections of unequal length to one another positioned over an alternating domain structure in an electrooptic substrate, and including a center section, or center pair of sections disposed asymmetrically between pairs surrounding sections. The surrounding pairs, comprise the two sections adjacent the center section or pair of sections, and each two sections adjacent the previous pair of sections, moving outwardly from the center to the final outermost pair, L1 and LN at the RF input 2 and RF output 4. In each pair, the section lengths are equal, or the section closer to the RF output 4 has a longer length than the section closer to the RF input 2. The surrounding pairs have lengths that decrease from the innermost pair to the outermost pair. For a zero chirp structure, the section lengths are selected to maintain an equivalent length for the inverted and uninverted domain sections.

Abstract: The invention relates to an electro-optic modulator structure containing an additional set of bias electrodes buried within the device for applying bias to set the operating point. Thus the RF electrodes used to modulate incoming optical signals can be operated with zero DC bias, reducing electrode corrosion by electro-migration, galvanic, and other effects that can be present in non-hermetic packages. The RF electrodes are supported by a first surface of the electro-optic substrate, while the bias electrodes are supported by a second opposite surface.

Abstract: The invention relates to an electro-optic modulator structure containing an additional set of bias electrodes buried within the device for applying bias to set the operating point. Thus the RF electrodes used to modulate incoming optical signals can be operated with zero DC bias, reducing electrode corrosion by galvanic and other effects that can be present in non-hermetic packages. The buried bias electrodes are also advantageous in controlling charge build-up with consequent improvement in drift characteristics. The bias electrode material is useful for routing bias signals inside the device, in particular to external terminals, as well as forming encapsulating layers to permit operation in non-hermetic environments, thereby lowering manufacturing costs. Embodiments using both X-cut and Z-cut lithium niobate (LiNbO3) are presented. For the latter, the bias electrodes can be split along their axis to avoid optical losses.

Abstract: The invention relates to an electro-optic modulator structure containing an additional set of bias electrodes buried within the device for applying bias to set the operating point. Thus the RF electrodes used to modulate incoming optical signals can be operated with zero DC bias, reducing electrode corrosion by galvanic and other effects that can be present in non-hermetic packages. The buried bias electrodes are also advantageous in controlling charge build-up with consequent improvement in drift characteristics. The bias electrode material is useful for routing bias signals inside the device, in particular to external terminals, as well as forming encapsulating layers to permit operation in non-hermetic environments, thereby lowering manufacturing costs. Embodiments using both X-cut and Z-cut lithium niobate (LiNbO3) are presented. For the latter, the bias electrodes can be split along their axis to avoid optical losses.

Abstract: An optical external modulator includes an optical waveguide having a first interferometer section and a second interferometer section formed on an electro-optic substrate. An electrode structure disposed on the substrate transmits an RF drive signal that is applied to the first and second interferometer sections in series. A reflector optically coupled to the substrate redirects light away from the first interferometer section to the second interferometer section and provides an optical fold region that introduces an optical time delay between the first and second interferometer sections. The optical time delay is used for at least partially compensating for a velocity mismatch between the light and the RF drive signal.