Reflection between a Mach-Zehnder modulator and a termination resistor is suppressed. An optical modulator includes a differential drive open collector driver IC, a differential drive semiconductor Mach-Zehnder modulator, and a differential terminator. The Mach-Zehnder modulator includes waveguides and a differential high-frequency line. The differential terminator includes a differential high-frequency line and termination resistors. The differential high-frequency line includes a capacity provided at least one of between signal lines and between a signal line and a ground line.

The invention relates to the field of photonic integrated circuits and provides an optical modulator and a photonic integrated system, which can suppress phase deviation caused by carrier diffusion. The optical modulator includes at least one phase shifter including a waveguide channel for transmitting optical signal, and a P-type doped region and a N-type doped region located on opposite sides of the waveguide channel. In the waveguide channel, an undoped intrinsic region is located between the P-type doped region and the N-type doped region. At least one end of the intrinsic region or close to the at least one end is provided with a blocking structure for blocking the diffusion of carriers from the intrinsic region along the waveguide propagation direction, so that the phase deviation caused by the diffusion of carriers can be suppressed, and the electrical crosstalk between adjacent phase shifters can be suppressed, thereby avoiding modulation signal distortion caused by the electrical crosstalk. As a result, the reliability and precision of the photonic integrated system can be improved.

The invention is notably directed to a transflective display device. The device comprises a set of pixels, wherein each of the pixels comprises a portion of bi-stable, phase change material, hereafter a PCM portion, having at least two reversibly switchable states, in which it has two different values of refractive index and/or optical absorption. The device further comprises one or more spacers, optically transmissive, and extending under PCM portions of the set of pixels. One or more reflectors extend under the one or more spacers. An energization structure is in thermal or electrical communication with the PCM portions, via the one or more spacers. Moreover, a display controller is configured to selectively energize, via the energization structure, PCM portions of the pixels, so as to reversibly switch a state of a PCM portion of any of the pixels from one of its reversibly switchable states to the other. A backlight unit is furthermore configured, in the device, to allow illumination of the PCM portions through the one or more spacers. The backlight unit is controlled by a backlight unit controller, which is configured for modulating one or more physical properties of light emitted from the backlight unit. The invention is further directed to related devices and methods of operation.

Aspects of this disclosure concern controllers and control methods for applying a drive voltage to bus bars of optically switchable devices such as electrochromic devices. Such devices are often provided on windows such as architectural glass. In certain embodiments, the applied drive voltage is controlled in a manner that efficiently drives an optical transition over the entire surface of the electrochromic device. The drive voltage is controlled to account for differences in effective voltage experienced in regions between the bus bars and regions proximate the bus bars. Regions near the bus bars experience the highest effective voltage. In some cases, feedback may be used to monitor an optical transition. In these or other cases, a group of optically switchable devices may transition together over a particular duration to achieve approximately uniform tint states over time during the transition.

A drive circuit for driving an electro-optical device like an optically switchable glazing, e.g. a glass panel provided with a PDLC or SPD layer, comprises a set of input terminals for receiving an alternating input voltage at a first frequency; a set of output terminals for supplying an alternating output voltage at a second frequency; a control circuit generating a control signal dependent on an input signal, the input signal representing a charge state of the electro-optical device; and a current-direction circuit for controlling a current-flow direction of an electrical current in response to the control signal. The control circuit and the current-direction circuit are thereby configured to control the second frequency such that the electro-optical device is prevented from degradation, while keeping an energy consumption low.

An optical transmission apparatus includes an emitter that emits an optical signal in accordance with a bias current, and a Mach-Zehnder optical modulator that optically modulates the optical signal in accordance with an electrical signal. The optical modulator includes a detector that detects a temperature inside the optical modulator, and a controller that, when detecting activation of a power supply, controls the temperature inside the optical modulator such that the temperature detected by the detector reaches a target temperature.

A system such as a vehicle, building, or electronic device system may have a support structure with one or more windows. The support structure and window may separate an interior region within the system from a surrounding exterior region. Control circuitry may receive input such as user input and may adjust an adjustable layer in the window based on the input. The adjustable layer may have a polymer matrix layer with embedded cells. The cells may include intermixed guest-host liquid crystal cells and liquid crystal cells. The guest-host liquid crystal cells and liquid crystal cells may have different liquid crystal materials and/or different sizes that allow the guest-host liquid crystal cells and liquid crystal cells to electrically switch states at different respective threshold voltages. Based on the user input or other input the control circuitry can adjust a drive signal across the adjustable layer to change light transmittance and haze.

An optical communication device may include a driver component, arranged to achieve a driving voltage, and a modulator component, including a laser or arranged to receive light from a laser. The modulator component may be arranged to achieve a modulated light signal modulated based on the driving voltage. The device may include a transmission line arranged to transfer the driving voltage between the driver component and the modulator component. The transmission line may not impedance matched to the driver component, the transmission line may have an impedance which is at least 20% lower than an output impedance of the driver component, and the transmission line may be impedance matched with respect to signal reflections to the modulator component.

A phase modulation active device and a method of driving the same are provided. The method may include configuring, for the phase modulation active device including a plurality of channels that modulate a phase of incident light, a phase profile indicating a phase modulation target value to be implemented by the phase modulation active device; setting a phase limit value of the phase modulation active device; generating a modified phase profile based on the phase profile by modifying the phase modulation target value, for at least one channel from the plurality of channels that meets or exceeds the phase limit value, to a modified phase modulation target value that is less than the phase limit value in the phase profile; and operating the phase modulation active device based on the modified phase profile. Thus, improved optical modulation performance may be achieved.

An optical semiconductor chip of the present disclosure includes a high frequency line between an electrode pad receiving a modulation signal and a modulation electrode on the optical waveguide having a light absorption layer. The depletion layer capacitance generated in the light absorption layer is canceled by an inductor component of the high frequency line. When a portion directly below the high frequency line is embedded with a low-dielectric-constant material or is made hollow, the parasitic capacitance is further reduced. The high frequency line may have a zigzag shape as well as a linear shape. The electrode pad on the optical semiconductor chip can be connected to other substrates including RF lines for modulation signal input by bumps or wire bonding.