Abstract: Devices and systems which include on-chip waveguides with flattened dispersion are described. In one aspect, silicon nitride slot waveguides that exhibit four zero-dispersion wavelengths with a flattened dispersion over a wavelength range of 500 nm are obtained. The disclosed silicon nitride slot waveguides are used to generate a two-octave supercontinuum from 630 nm to 2650 nm, enabling (a) on-chip generation of 5 fs optical pulses as short as 1.3 cycles, and (b) sensitive single-shot measurements of the absolute carrier-envelope phase using a single integrated waveguide. In another aspect, silicon slot waveguides that exhibits four zero-dispersion wavelengths with a flattened dispersion over a wavelength range of 670-nm are obtained. An octave-spanning supercontinuum is generated in the disclosed silicon slot waveguide, over a wavelength range from 1217 nm to 2451 nm, approximately from bandgap wavelength to half-bandgap wavelength.

Abstract: Nondegenerate mirrorless four-wave mixing oscillation with frequency tunability is proposed in nonlinear waveguide of the third-order nonlinearity such as silicon waveguide) by using two different spatial modes. As low as ˜2 W threshold power is obtained in several centimeters long waveguide. In one aspect, a method includes propagating a first wave along an axis of a multimode waveguide in a forward direction, the first optical wave having a first frequency; propagating a second wave along the axis of the multimode waveguide in a backward direction, the second wave having a second frequency; the waveguide configured to support multiple modes, including at least a fundamental mode and a second mode; and the propagating the first wave occurs at a same time as the propagating the second wave to generate a third wave in the forward direction having a third frequency and fourth wave in the backward direction having a fourth frequency.

Abstract: Methods, systems and devices implement optical tapped delay lines. In one aspect, a device includes an optical tapped delay (TDL) including a wavelength conversion element, and a dispersive element, coupled with the wavelength conversion element, to impose a relative delay to an optical signal. The optical TDL can include a nonlinear element to combine signals in a phase coherent manner. The wavelength conversion element can include an optical nonlinear device such as a periodically poled lithium niobate (PPLN) or a highly nonlinear fiber (HNLF) with a high nonlinear coefficient and a low dispersion slope to effect four-wave mixing (FWM). The dispersive element can have a low dispersion slope, and the delays effected by the optical TDL can be tunable.

Abstract: Methods and systems used to perform sweep-free stimulated Brillouin scattering-based fiber optical sensing are described. In one aspect, a method includes interrogating different parts of a Brillouin gain spectrum using multiple optical tones in an optical fiber. The interrogating includes sending at least two pump tones into the optical fiber from one end of the optical fiber, such that a frequency spacing between the pump tones is larger than a width of the Brillouin gain spectrum. The interrogating also includes sending at least two probe tones into the optical fiber from another end of the optical fiber, such that a frequency spacing between the probe tones is different from the frequency spacing between the pump tones. The method further includes generating a sensing output based on the interrogating.

Abstract: The present disclosure includes systems and techniques relating to reconfigurable optical transmitters. In some implementations, an apparatus, systems, or methods can include multiple ports to receive independent optical data signals or independent electrical signals that are converted into independent optical data signals, at least one optical pump laser, and one or more nonlinear optics elements configured and arranged to generate a phase conjugate for each of the independent optical data signals at least by combining the respective independent optical data signal with an output of the optical pump, and generate an output optical signal from the independent optical data signals at least by combining each of the independent optical data signals with its corresponding generated phase conjugate.

Abstract: Systems, devices, and techniques are disclosed relating to dispersion devices that include a slot waveguide coupled with another waveguide such as a strip waveguide. For example, one or more structural parameters can be obtained for a dispersion device, including a slot waveguide coupled to a strip waveguide, to cause the dispersion device to produce dispersion, having a dispersion profile, for an electromagnetic wave propagated through the dispersion device, the one or more structural parameters including one or more of a slot thickness for a slot of the slot waveguide or a spacing thickness between the slot waveguide and the other waveguide; and making the dispersion device, including the slot waveguide and the other waveguide, according to the structural parameters.

Abstract: Methods and systems used to perform sweep-free stimulated Brillouin scattering-based fiber optical sensing are described. In one aspect, a method includes interrogating different parts of a Brillouin gain spectrum using multiple optical tones in an optical fiber. The interrogating includes sending at least two pump tones into the optical fiber from one end of the optical fiber, such that a frequency spacing between the pump tones is larger than a width of the Brillouin gain spectrum. The interrogating also includes sending at least two probe tones into the optical fiber from another end of the optical fiber, such that a frequency spacing between the probe tones is different from the frequency spacing between the pump tones. The method further includes generating a sensing output based on the interrogating.

Abstract: Systems, devices, and techniques are disclosed relating to dispersion devices that include a slot waveguide coupled with another waveguide such as a strip waveguide. For example, one or more structural parameters can be obtained for a dispersion device, including a slot waveguide coupled to a strip waveguide, to cause the dispersion device to produce dispersion, having a dispersion profile, for an electromagnetic wave propagated through the dispersion device, the one or more structural parameters including one or more of a slot thickness for a slot of the slot waveguide or a spacing thickness between the slot waveguide and the other waveguide; and making the dispersion device, including the slot waveguide and the other waveguide, according to the structural parameters.

Abstract: An optical code division multiple access (OCDMA) system includes an optical transmitter system configured to transmit data from a plurality of users through a shared optical channel by encoding the data from each user with a spreading code assigned to that user. Each spreading code includes a unique sequence of T time chips along a time axis. The data from each user is representable by T symbols. The OCDMA system further includes an optical receiver system configured to demodulate the data from each user by correlating signals received from the transmitter system with the spreading code assigned to that user. When transmitting a data symbol for each user, the transmitter system selects one out of T distinct cyclic shifts of the spreading code assigned to that user, and transmits the selected cyclic shift of the assigned spreading code along the time axis.

Abstract: Systems and techniques to optically boost a router. In general, in one implementation, the technique includes: receiving an optical signal defining a packet of data, initiating electronic routing of the optical packet, and initiating optical routing of the optical packet. The optical routing involves determining forwarding information based on a routing field in the optical packet, and if optical forwarding is available, terminating the electronic routing of the packet before completion of the electronic routing, and forwarding the optical signal, which defines the packet, based on the determined forwarding information.

Abstract: A multi-wavelength optical signal copropagates through a fiber-optic communication link with a continuous-wave ancillary wavelength having an unknown state of polarization (SOP), which is scrambled periodically in time. The instantaneous value of polarization dependent loss (PDL) in the ancillary wavelength is monitored in real time, and is used as an error signal to adjust at least one polarization controller. Polarization scrambling is performed by periodically changing the SOP with time, such that the polarization-scrambled optical signal covers approximately an entire Poincaré sphere surface, preferably uniformly, during each time period. At an optical node between fibers, an adjustable PDL compensator contains two ordered pairs each consisting of one polarization controller and one optical element introducing fixed PDL.

Abstract: Techniques for monitoring frequency-dependent parameter and optical property such as optical dispersion in a modulated optical signal with sidebands based on optical vestigial sideband filtering. Monitoring implementations for both chromatic dispersion and polarization-mode dispersion are described as examples.

Abstract: Techniques, devices, and systems for generating tunable dispersions to control or compensate for dispersions in optical signals by using wave-guiding grating elements with nonlinear group delays.

Abstract: A method for tunable optical pulse width generation comprises varying chirp of the signal of the pulse and concurrently varying dispersion of the signal. A system for tunable pulse width generation comprises a phase modulator providing the chirp modulation by modulating peak to peak phase of an optical signal and a tunable dispersion element providing the chromatic dispersion to the optical signal. A system for tunable pulse width return to zero optical signal transmission comprises at least one optical signal, a plurality of amplitude modulators for modulating the signal and a tunable pulse width generator comprising a phase modulator providing the chirp modulation and a tunable dispersion element providing the dispersion.

Abstract: Techniques and devices for providing reconfigurable and variable-bit-rate optical header recognition for an optical switch.

Abstract: Methods and systems for implementing polarization division multiplexing to allow recovery of data in different multiplexed channels at a receiving end without recovering multiplexed polarizations used in the transmitting stage.

Abstract: Techniques and devices for controlling or compensating for both the first-order and high-order PMD effects in an optical signal by processing the signal in a fixed DGD stage and a variable DGD stage in sequence.

Abstract: Techniques and systems for mitigating polarization-related signal degradation or distortions in birefringent optical links based on intra-bit polarization diversity modulation.

Abstract: Wideband optical amplifiers that use two parallel amplifiers in different operating spectral ranges and two different or identical sampled Bragg gratings as the channel splitter and combiner.

Abstract: Techniques for compensating for PMD in multiple WDM channels by processing all WDM channels in the same manner without demultpliexing the channels. A feedback control is provided to decrease the worst-case power penalty and the channel fading probability by optimizing over the entire group of WDM channels.