Abstract: A low loss high extinction ratio on-chip polarizer is disclosed. The polarizer includes an input waveguide taper having an outer waveguiding region that widens in the direction of light propagation along at least a portion of the taper length, and a core waveguiding region that narrows in the direction of light propagation along at least a portion of the taper length, so as to selectively squeeze out light of undesired modes into the outer regions while preserving light of a desired mode in the waveguide core. An output filter section is provided to prevent light from reentering the output waveguide after being squeezed out. An integrated light absorber/deflector may be coupled to the outer waveguiding regions.

Abstract: An optical waveguide modulator with automatic bias control is disclosed. A dither signal is applied to the modulator bias and its signature detected in light tapped from an output of the modulator using a phase sensitive dither detector such as a lock-in amplifier. The detected signal is processed using pre-recorded information defining the direction of the detected signal change relative to a change in the modulator bias, and the bias is adjusted in the direction determined using the information. An IQ bias of a quadrature modulator is controlled by dithering bias settings of two inner modulators at different dither frequencies, and detecting an oscillation at a sum frequency.

Abstract: A test system for determining a surface characteristic of a chip facet comprises a chip, which has a facet and includes a waveguide, a detector, and a processor. The on-chip waveguide is configured to direct test light towards the facet, where a portion of the test light is reflected and a portion of the test light is transmitted. The detector is configured to measure an amount of the reflected portion or the transmitted portion, and the processor is configured to determine a surface characteristic of the facet, such as a facet angle, a facet curvature, and/or a facet roughness, on the basis of the measured amount.

Abstract: A transceiver having an improved transmitter optical signal to noise ratio, and methods of making and using the same.

Abstract: A skew compensation apparatus and method. In an optical system that uses optical signals, skew may be generated as the optical signals are processed from an input optical signal to at least two electrical signals representative of the phase-differentiated optical signals. A compensation of the skew is provided by including an optical delay line in the path of the optical signal that does not suffer the skew (e.g., that serves as the time base for the skew measurement). The optical delay line introduces a delay Tskew equal to the delay suffered by the optical signal that is not taken as the time base. The two signals are thereby corrected for skew.

Abstract: A test system for determining a surface characteristic of a chip facet comprises a chip, which has a facet and includes a waveguide, a detector, and a processor. The on-chip waveguide is configured to direct test light towards the facet, where a portion of the test light is reflected and a portion of the test light is transmitted. The detector is configured to measure an amount of the reflected portion or the transmitted portion, and the processor is configured to determine a surface characteristic of the facet, such as a facet angle, a facet curvature, and/or a facet roughness, on the basis of the measured amount.

Abstract: A skew compensation apparatus and method. In an optical system that uses optical signals, skew may be generated as the optical signals are processed from an input optical signal to at least two electrical signals representative of the phase-differentiated optical signals. A compensation of the skew is provided by including an optical delay line in the path of the optical signal that does not suffer the skew (e.g., that serves as the time base for the skew measurement). The optical delay line introduces a delay Tskew equal to the delay suffered by the optical signal that is not taken as the time base. The two signals are thereby corrected for skew.

Abstract: A transceiver having an improved transmitter optical signal to noise ratio, and methods of making and using the same.

Abstract: An optical waveguide modulator with automatic bias control is disclosed. A dither signal is applied to the modulator bias and its signature detected in light tapped from an output of the modulator using a phase sensitive dither detector such as a lock-in amplifier. The detected signal is processed using pre-recorded information defining the direction of the detected signal change relative to a change in the modulator bias, and the bias is adjusted in the direction determined using the information. An IQ bias of a quadrature modulator is controlled by dithering bias settings of two inner modulators at different dither frequencies, and detecting an oscillation at a sum frequency.

Abstract: A low loss high extinction ratio on-chip polarizer is disclosed. The polarizer includes an input waveguide taper having an outer waveguiding region that widens in the direction of light propagation along at least a portion of the taper length, and a core waveguiding region that narrows in the direction of light propagation along at least a portion of the taper length, so as to selectively squeeze out light of undesired modes into the outer regions while preserving light of a desired mode in the waveguide core. An output filter section is provided to prevent light from reentering the output waveguide after being squeezed out. An integrated light absorber/deflector may be coupled to the outer waveguiding regions.

Abstract: A method for on-wafer testing of optical structures of photonic chips that include edge couplers as input/out ports includes defining, in test a test area of the wafer, an edge coupler pair formed of two edge couplers separated by a test gap, which may have a width that is close to the width of a chip-fiber gap during normal operation of the photonic chips. Test areas may include chains of different numbers of the edge coupler pairs for determining coupling loss per edge coupler.

Abstract: Back scattering in an optical waveguide at an operating wavelength is controlled by adjusting an optical phase of light propagating in the waveguide at one or more locations along the waveguide. A portion of the back scattered light is tapped off near an input port and coupled into a photodetector. A controller detects changes in the photodetector signal and adjusts an optical phase tuner configured to control the optical phase of light in the waveguide at the selected location or locations. The optical phase tuner may be configured to vary the refractive index of at least a portion of the waveguide.

Abstract: An optical waveguide modulator with automatic bias control is disclosed. A dither signal is applied to the modulator bias and its signature detected in light tapped from an output of the modulator using a phase sensitive dither detector such as a lock-in amplifier. The detected signal is processed using pre-recorded information defining the direction of the detected signal change relative to a change in the modulator bias, and the bias is adjusted in the direction determined using the information. An IQ bias of a quadrature modulator is controlled by dithering bias settings of two inner modulators at different dither frequencies, and detecting an oscillation at a sum frequency.

Abstract: A low loss high extinction ratio on-chip polarizer. The polarizer includes an input waveguide taper having an outer waveguiding region that widens in the direction of light propagation along at least a portion of the taper length, and a core waveguiding region that narrows in the direction of light propagation along at least a portion of the taper length, so as to selectively squeeze out light of undesired modes into the outer regions while preserving light of a desired mode in the waveguide core. An output filter section is provided to prevent light from reentering the output waveguide after being squeezed out. An integrated light absorber/deflector may be coupled to the outer waveguiding regions.

Abstract: A test system for determining a surface characteristic of a chip facet comprises a chip, which has a facet and includes a waveguide, a detector, and a processor. The on-chip waveguide is configured to direct test light towards the facet, where a portion of the test light is reflected and a portion of the test light is transmitted. The detector is configured to measure an amount of the reflected portion or the transmitted portion, and the processor is configured to determine a surface characteristic of the facet, such as a facet angle, a facet curvature, and/or a facet roughness, on the basis of the measured amount.

Abstract: An optical waveguide modulator with automatic bias control is disclosed. A portion of the modulator light is mixed with reference light and converted to one or more electrical feedback signals. An electrical feedback circuit controls the modulator bias responsive to the feedback signals.

Abstract: A transceiver having an improved transmitter optical signal to noise ratio, and methods of making and using the same.

Abstract: A test system for determining a surface characteristic of a chip facet includes an on-chip waveguide, a detector, and a processor. The on-chip waveguide is configured to direct test light towards the facet, where a portion of the test light is reflected and a portion of the test light is transmitted. The detector is configured to measure an amount of the reflected portion or the transmitted portion, and the processor is configured to determine a surface characteristic of the facet, such as a facet angle, a facet curvature, and/or a facet roughness, on the basis of the measured amount.

Abstract: A qualification apparatus for a photonic chip on a wafer that leaves undisturbed an edge coupler that provides an operating port for the photonic devices or circuits on the chip during normal operation in order to not introduce extra loss in the optical path of the final circuit. The qualification apparatus provides an optical path that is angled with regard to the surface of the chip, for example by using a grating coupler. The qualification apparatus can be removed after the chip is qualified. Optionally, the qualification apparatus can be left in communication with the chip and optionally employed as an input port for the chip after the chip has been separated from other chips on a common substrate.

Abstract: Back scattering in an optical waveguide at an operating wavelength is controlled by adjusting an optical phase of light propagating in the waveguide at one or more locations along the waveguide. A portion of the back scattered light is tapped off near an input port and coupled into a photodetector. A controller detects changes in the photodetector signal and adjusts an optical phase tuner configured to control the optical phase of light in the waveguide at the selected location or locations. The optical phase tuner may be configured to vary the refractive index of at least a portion of the waveguide.