Abstract: An optical transceiver in an optical communications network, comprising a receiver configured to receive an optical signal comprising an X-polarization component and a Y-polarization component. The optical transceiver further comprises a processor coupled to the receiver and configured to determine a chromatic dispersion (CD) estimate and a local oscillator frequency offset (LOFO) estimate based on a relationship between a plurality of CD values and a plurality of LOFO values. The optical transceiver further comprises a transmitter coupled to the processor and configured to transmit the CD estimate, the LOFO estimate, and the optical signal to a downstream component in the optical communications network.

Abstract: An optical modulator comprises a silicon substrate, a buried oxide (BOX) layer disposed on top of the silicon substrate, and a ridge waveguide disposed on top of the BOX layer and comprising a first n-type silicon (n-Si) slab, a first gate oxide layer coupled to the first n-Si slab, a first p-type silicon (p-Si) slab coupled to the first gate oxide layer, and a light propagation path that travels sequentially through the first n-Si slab, the first gate oxide layer, and the first p-Si slab.

Abstract: A method for fabricating a photonic integrated circuit (PIC) comprises providing a wafer comprising an insulator layer positioned between a top semiconductor layer and a base semiconductor layer, patterning the top semiconductor layer to simultaneously define a waveguide and a first etch mask window for forming a fiber-guiding v-groove that substantially aligns to an axis of optical signal propagation of the waveguide, removing a first portion of the top semiconductor layer to form the waveguide according to the patterning, removing a second portion of the top semiconductor layer to form the first etch mask window according to the patterning, and forming the fiber-guiding v-groove according to the first etch mask window.

Abstract: An apparatus comprises a transistor outline (TO) package comprising a TO can holder; and a TO can at least partially embedded within the TO can holder; and a mode converter coupled to the TO package. A system comprises a mode converter comprising a lens configured to convert a mode of a light from a first mode size to a second mode size, wherein the first mode size is smaller than the second mode size; a silicon photonic chip comprising a waveguide configured to communicate the light; a fiber configured to couple to the lens and the waveguide; and a substrate configured to provide a support for the silicon photonic chip.

Abstract: An apparatus comprises: a first input tap; a first optical modulator coupled to the first input tap; a first output tap coupled to the first optical modulator so that the first optical modulator is positioned between the first input tap and the first output tap; and a controller indirectly coupled to the first input tap and the first output tap.

Abstract: An optical modulator comprising a waveguide for propagating an optical signal comprising a proximate arm configured to communicate a proximate portion of the optical signal, and a distal arm configured to communicate a distal portion of the optical signal, a proximate diode configured to modulate the proximate portion of the optical signal, a distal diode configured to modulate the distal portion of the optical signal, and an electrical input electrically coupled to opposite signed interfaces of the proximate diode and the distal diode such that an electrical driving signal propagated along the electrical input causes an equal and opposite modulation of the proximate portion of the optical signal in the proximate arm of the waveguide and the distal portion of the optical signal in the distal arm of the waveguide.

Abstract: An optical transceiver in an optical communications network, comprising a receiver configured to receive an optical signal comprising an X-polarization component that comprises a first frame and a Y-polarization component that comprises a second frame. The optical transceiver also comprises a processor coupled to the receiver and configured to determine, in a time domain, a phase estimate according to the first frame and the second frame, determine, in a frequency domain, a channel estimate for the optical signal according to a relationship between the first frame, the second frame, and the phase estimate, and determine a compensated optical signal according to the channel estimate. The optical transceiver further comprises a transmitter coupled to the processor and configured to transmit the compensated optical signal to a downstream component in the optical communications network.

Abstract: An optical transceiver in an optical communications network, comprising a receiver configured to receive an optical signal comprising an X-polarization component that comprises a first frame and a Y-polarization component that comprises a second frame. The optical transceiver also comprises a processor coupled to the receiver and configured to determine, in a time domain, a phase estimate according to the first frame and the second frame, determine, in a frequency domain, a channel estimate for the optical signal according to a relationship between the first frame, the second frame, and the phase estimate, and determine a compensated optical signal according to the channel estimate. The optical transceiver further comprises a transmitter coupled to the processor and configured to transmit the compensated optical signal to a downstream component in the optical communications network.

Abstract: An apparatus comprising a modulation block comprising a plurality of modulators, wherein each of the plurality of modulators comprises an optical input port and an optical output port, and wherein all of the optical input ports and all of the optical output ports are positioned on one face of the modulation block. Another apparatus comprising a modulation block comprising one or more Mach-Zehnder modulators (MZMs), wherein each MZM is coupled to an optical input port, an optical output port, and at least one electrical trace, wherein all of the optical input ports and all of the optical output ports are positioned on a first side of the modulation block, and wherein all of the electrical traces are positioned on a second side of the modulation block, and a planar lightwave circuit (PLC) coupled to the modulation block via an optical interface.

Abstract: An optical transceiver in an optical communications network, comprising a receiver configured to receive an optical signal comprising an X-polarization component and a Y-polarization component. The optical transceiver further comprises a processor coupled to the receiver and configured to determine a chromatic dispersion (CD) estimate and a local oscillator frequency offset (LOFO) estimate based on a relationship between a plurality of CD values and a plurality of LOFO values. The optical transceiver further comprises a transmitter coupled to the processor and configured to transmit the CD estimate, the LOFO estimate, and the optical signal to a downstream component in the optical communications network.

Abstract: A first optical transceiver node comprises: a laser configured to emit an input optical signal; a first splitter coupled to the laser and configured to split the input optical signal into a local oscillator (LO) optical signal and an unmodulated optical signal; and a receiver coupled to the first splitter and configured to: receive the LO optical signal from the first splitter; receive a modulated optical signal from a second optical transceiver node, wherein the modulated optical signal is a modulated version of the unmodulated optical signal; and perform phase noise cancellation of the modulated optical signal using the LO optical signal.

Abstract: An optical modulator for generating quadrature amplitude modulation (nQAM) and phase-shift keying (nPSK) signals with tunable modulation efficiency. The modulator includes a controlling circuit for adjusting the modulation efficiency or modulation depth of the modulator by controlling the direct current (DC) bias.

Abstract: A signal processing method including obtaining, using an optical receiver, a data signal that comprises one or more pairs of pilot tones and a plurality of subcarrier signals, identifying the one or more pairs of pilot tones, determining a local oscillator frequency offset estimation for the data signal using the one or more pairs of pilot tones, wherein the local oscillator frequency offset estimation indicates a frequency offset, and compensating the data signal in accordance with the local oscillator frequency offset estimation. A signal processing method including obtaining, using an optical receiver, a data signal that comprises one or more pairs of pilot tones and a plurality of subcarrier signals, identifying the one or more pairs of pilot tones, determining a chromatic dispersion estimation for the data signal using the one or more pairs of pilot tones, and compensating the data signal in accordance with the chromatic dispersion estimation.

Abstract: An apparatus comprising a waveguide along a longitudinal axis at a first elevation, an optical splitter coupled to a first edge of the waveguide along the longitudinal axis, two or more inverse tapers coupled to a second edge of the optical splitter along the longitudinal axis, and one or more offset inverse tapers that are substantially parallel with the two or more inverse tapers, wherein the one or more offset inverse tapers are along the longitudinal axis at a second elevation.

Abstract: A signal processing method including obtaining, using an optical receiver, a data signal that comprises one or more pairs of pilot tones and a plurality of subcarrier signals, identifying the one or more pairs of pilot tones, determining a local oscillator frequency offset estimation for the data signal using the one or more pairs of pilot tones, wherein the local oscillator frequency offset estimation indicates a frequency offset, and compensating the data signal in accordance with the local oscillator frequency offset estimation. A signal processing method including obtaining, using an optical receiver, a data signal that comprises one or more pairs of pilot tones and a plurality of subcarrier signals, identifying the one or more pairs of pilot tones, determining a chromatic dispersion estimation for the data signal using the one or more pairs of pilot tones, and compensating the data signal in accordance with the chromatic dispersion estimation.

Abstract: A method includes forming a first optical structure with an inverse taper and a separate optical structure on a semiconductor chip. The illustrative method also includes applying a protective structure over the optical structures and patterning the protective structure to expose the separate optical structure. The method further includes removing a portion of the separate optical structure to form a separate trimmed taper separate from, but adjacent to, the first optical structure. The protective structure is then removed from the first optical structure. Apparatuses are also disclosed.

Abstract: An apparatus comprising a modulation block comprising a plurality of modulators, wherein each of the plurality of modulators comprises an optical input port and an optical output port, and wherein all of the optical input ports and all of the optical output ports are positioned on one face of the modulation block. Another apparatus comprising a modulation block comprising one or more Mach-Zehnder modulators (MZMs), wherein each MZM is coupled to an optical input port, an optical output port, and at least one electrical trace, wherein all of the optical input ports and all of the optical output ports are positioned on a first side of the modulation block, and wherein all of the electrical traces are positioned on a second side of the modulation block, and a planar lightwave circuit (PLC) coupled to the modulation block via an optical interface.

Abstract: An electronic driver circuit for use with a modulator such as a segmented Mach-Zehnder Modulator (MZM) is provided. The electronic driver circuit includes a first delay buffer implemented as a first complementary metal-oxide-semiconductor (CMOS) inverter and a second delay buffer implemented as a second CMOS inverter. The second CMOS inverter follows the first CMOS inverter and has a second gate width smaller than a first gate width of the first CMOS inverter. The first CMOS inverter is configured to produce a first delayed electrical signal from a received electrical signal and the second CMOS inverter is configured to produce a second delayed electrical signal from the first delayed electrical signal produced by the first CMOS inverter.

Abstract: An apparatus comprising an optical input configured to receive an optical carrier, an polarization beam splitter configured to forward a first polarized component of the optical carrier along a first light path, and forward a second polarized component of the optical carrier along a second light path, wherein the first polarized component comprises a first polarization that is perpendicular to a second polarization of the second polarized component upon exiting the optical splitter, and an optical modulator coupled to the first light path and the second light path, the modulator configured to modulate the first polarized component of the optical carrier and the second polarized component of the optical carrier.

Abstract: A first optical transceiver node comprises: a laser configured to emit an input optical signal; a first splitter coupled to the laser and configured to split the input optical signal into a local oscillator (LO) optical signal and an unmodulated optical signal; and a receiver coupled to the first splitter and configured to: receive the LO optical signal from the first splitter; receive a modulated optical signal from a second optical transceiver node, wherein the modulated optical signal is a modulated version of the unmodulated optical signal; and perform phase noise cancellation of the modulated optical signal using the LO optical signal.