Abstract: An optical resonant modulator based on coupling modulation, comprising a resonant structure with an embedded Mach-Zehnder interferometer that is differentially driven to induced amplitude modulation at the output port. The principle of coupling modulation enables high data/baud rates to be achieved in a photonic integrated circuit, e.g. silicon, footprint that is considerably smaller than that of a conventional traveling-wave Mach-Zehnder modulator, in particular by utilizing space saving features, such as ring resonator phase shifters and bend waveguide arms.

Abstract: An optical resonant modulator based on coupling modulation, comprising a resonant structure with an embedded Mach-Zehnder interferometer that is differentially driven to induced amplitude modulation at the output port. The principle of coupling modulation enables high data/baud rates to be achieved in a photonic integrated circuit, e.g. silicon, footprint that is considerably smaller than that of a conventional traveling-wave Mach-Zehnder modulator, in particular by utilizing space saving features, such as ring resonator phase shifters and bend waveguide arms.

Abstract: A multi-section optical modulator and related method are disclosed wherein two waveguide arms traverse a plurality of successive modulating sections. A differential drive signal is applied separately to each waveguide arm of each modulating sections in synchronism with the transmission of light along the waveguide arms, effecting a dual differential driving of each section. By suitably selecting the number of modulating sections and the section length, a high modulation bandwidth and a high modulation efficiency may be achieved simultaneously for a given peak-to-peak voltage swing of the drive signal.

Abstract: An apparatus includes a lithium niobate (LN) layer, and a planar electro-optical modulator having at least one hybrid optical core segment formed of a portion of the LN layer and an optical guiding rib. The optical guiding rib may be located in a top silicon layer of a silicon photonics (SiP) chip, to which a thin-film LN chip is flip-chip mounted, and may be coupled to optical waveguide cores in a first silicon core layer of the SiP chip. One or more drive electrodes are disposed between a substrate of the SiP chip and the LN layer. In some embodiments hybrid optical core segments may include silicon nitride core segments and may form an MZM configured to be differentially or dual-differentially driven.

Abstract: In optical receivers, extending the transimpedance amplifier's (TIA) dynamic range is a key to increasing the receiver's dynamic range, and therefore increase the channel capacity. Ideally, the TIA requires controllable gain, whereby the receiver can modify the characteristics of the TIA and/or the VGA to process high power incoming signals with a defined maximum distortion, and low power incoming signals with a defined maximum noise. A solution to the problem is to provide TIA's with reconfigurable feedback resistors, which are adjustable based on the level of power, e.g. current, generated by the photodetector, and variable load resistors, which are adjustable based on the change in impedance caused by the change in the feedback resistor.

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.

Abstract: A multi-section optical modulator and related method are disclosed wherein two waveguide arms traverse a plurality of successive modulating sections. A differential drive signal is applied separately to each waveguide arm of each modulating sections in synchronism with the transmission of light along the waveguide arms, affecting a dual differential driving of each section. By suitably selecting the number of modulating sections and the section length, a high modulation bandwidth and a high modulation efficiency may be achieved simultaneously for a given peak-to-peak voltage swing of the drive signal.

Abstract: A multi-section optical modulator and related method are disclosed wherein two waveguide arms traverse a plurality of successive modulating sections. A differential drive signal is applied separately to each waveguide arm of each modulating sections in synchronism with the transmission of light along the waveguide arms, affecting a dual differential driving of each section. By suitably selecting the number of modulating sections and the section length, a high modulation bandwidth and a high modulation efficiency may be achieved simultaneously for a given peak-to-peak voltage swing of the drive signal.

Abstract: Modern modulator drivers must be capable of delivering a large output voltage into a tens of ohms modulator, while minimizing the amount of distortion added by the driver. The driver should deliver the output voltage without exceeding a maximum distortion while minimizing the DC power consumption. Accordingly, a modulator driver includes a final stage amplifier with auxiliary transistors that turn on when the conventional differential pair of transistors approaches their maximum voltage of the linear region of their transfer function, thereby providing a more linear transfer function, in particular at large input voltages.

Abstract: Within a modulator driver, different blocks are employed, e.g. a buffer, one or more variable gain amplifiers (VGA), and a final driver stage. Each of these blocks has an optimum bias point for best performance; however, interconnecting the blocks requires sharing the DC bias points in their interface, which does not necessarily match the optimum performance bias point of each block. Accordingly, a first offset feedback loop extending from reference points after a selected one of the blocks to an input of one of the blocks. The first offset feedback loop includes current sources capable of delivering a variable current to the input of the selected block in order to compensate any offset in an amplified differential input electrical signal measured at the reference points. A first bias feedback loop is also provided, including a current sinker for subtracting excess current introduced in the first offset compensation feedback loop.

Abstract: In optical receivers, extending the transimpedance amplifier's (TIA) dynamic range is a key to increasing the receiver's dynamic range, and therefore increase the channel capacity. Ideally, the TIA requires controllable gain, whereby the receiver can modify the characteristics of the TIA and/or the VGA to process high power incoming signals with a defined maximum distortion, and low power incoming signals with a defined maximum noise. A solution to the problem is to provide TIA's and VGA's with reconfigurable sizes, which are adjustable based on the level of power, e.g. current, generated by the photodetector.

Abstract: In high data rate receivers, comprising a photodetector (PD) and a transimpedance amplifier (TIA), a transmitted optical signal typically has poor extinction ratio, which translates into a small modulated current with a large DC current at the output of the PD. The large DC current saturates the TIA, which significantly degrades the gain and bandwidth performance. Accordingly, cancelling photo diode DC current in high data rate receivers is important for proper receiver operation. A DC current cancellation loop, comprising a low pass filter section and a trans-conductance cell (GM) are connected to the input of the TIA. PD DC current IDC is drawn from the input node of the TIA in the GM cell, such that the cancellation loop maintains the DC voltage value of the TIA input node to be the same as a reference voltage (VREF).

Abstract: A coherent optical receiver for AM optical signals has a photonic integrated circuit (PIC) as an optical front-end. The PIC includes a polarization beam splitter followed by two optical hybrids each followed by an opto-electric (OE) converter. Each OE converter includes one or more differential detectors and one or more squaring circuits, which outputs may be summed. The PIC may further include integrated polarization controllers, wavelength demultiplexers, and/or tunable dispersion compensators.

Abstract: In optical receivers, cancelling the DC component of the incoming current is a key to increasing the receiver's effectiveness, and therefore increase the channel capacity. Ideally, the receiver includes a DC cancellation circuit for removing the DC component; however, in differential receivers an offset may be created between the output voltage components caused by the various amplifiers. Accordingly, an offset cancellation circuit is required to determine the offset and to modify the DC cancellation circuit accordingly.

Abstract: Within a modulator driver, different blocks are employed, e.g. a buffer, one or more variable gain amplifiers (VGA), and a final driver stage. Each of these blocks has an optimum bias point for best performance; however, interconnecting the blocks requires sharing the DC bias points in their interface, which does not necessarily match the optimum performance bias point of each block.. Accordingly, a first offset feedback loop extending from reference points after a selected one of the blocks to an input of one of the blocks. The first offset feedback loop includes current sources capable of delivering a variable current to the input of the selected block in order to compensate any offset in an amplified differential input electrical signal measured at the reference points. A first bias feedback loop is also provided, including a current sinker for subtracting excess current introduced in the first offset compensation feedback loop.

Abstract: An optical coherent receiver includes an optical hybrid (OH) configured to mix signal and reference light, and two back-end optical ports. An optical equalizing network interconnects two 180° OH output ports with the two back-end optical ports so that each back-end optical port receives light from each of the two OH output ports. Optical signals from each of the two back-end optical ports are converted to electrical signals that are fed to a differential amplifier. Adjusting coupling ratios and/or optical delays in the optical equalizing network reduces an OSNR penalty of a lower-bandwidth differential amplifier.

Abstract: A coherent optical receiver for AM optical signals has a photonic integrated circuit (PIC) as an optical front-end. The PIC includes a polarization beam splitter followed by two optical hybrids each followed by an opto-electric (OE) converter. Each OE converter includes one or more differential detectors and one or more squaring circuits, which outputs may be summed. The PIC may further include integrated polarization controllers, wavelength demultiplexers, and/or tunable dispersion compensators.

Abstract: A dual-differential optical modulator includes two optical waveguide arms, each including one or more phase modulating p/n junctions. The p/n junctions in each waveguide arm are electrically coupled between a same pair of single-ended transmission lines so as to be differentially push-pull modulated when the transmission line pair is connected to a differential driver. Either cathode or anode electrodes of the p/n junctions are AC coupled to the transmission lines and DC biased independently on the transmission line signals.

Abstract: Modern modulator drivers must be capable of delivering a large output voltage into a tens of ohms modulator, while minimizing the amount of distortion added by the driver. The driver should deliver the output voltage without exceeding a maximum distortion while minimizing the DC power consumption. Accordingly, a modulator driver includes a final stage amplifier with auxiliary transistors that turn on when the conventional differential pair of transistors approaches their maximum voltage of the linear region of their transfer function, thereby providing a more linear transfer function, in particular at large input voltages.

Abstract: In conventional optical receivers the dynamic range is obtained by using variable gain amplifiers (VGA) with a fixed trans-impedance amplifier (TIA) gain. To overcome the SNR problems inherent in conventional receivers an improved optical receiver comprises an automatic gain control loop for generating at least one gain control signal for controlling gain of both the VGA and the TIA. Ideally, both the resistance and the gain of the TIA are controlled by a gain control signal.