A diffractive network is disclosed that utilizes, in some embodiments, diffractive elements, which are used to shape an arbitrary broadband pulse into a desired optical waveform, forming a compact and passive pulse engineering system. The diffractive network was experimentally shown to generate various different pulses by designing passive diffractive layers that collectively engineer the temporal waveform of an input terahertz pulse. The results constitute the first demonstration of direct pulse shaping in terahertz spectrum, where the amplitude and phase of the input wavelengths are independently controlled through a passive diffractive device, without the need for an external pump. Furthermore, a modular physical transfer learning approach is presented to illustrate pulse-width tunability by replacing part of an existing diffractive network with newly trained diffractive layers, demonstrating its modularity. This learning-based diffractive pulse engineering framework can find broad applications in e.g., communications, ultra-fast imaging and spectroscopy.

A hair coloring appliance includes a handle and a hair color delivery system supported within the handle. A nozzle assembly is adapted to receive hair color. The nozzle assembly includes a stationary frame and a nozzle array through which the hair color is delivered to the hair and a plurality of filaments adjacent the nozzles which are longer than the nozzles, acting as a stand-off between the nozzles and the scalp. A motor reciprocates the nozzle array back and forth as hair color moves through the nozzles.

Recent remarkable progress in wave-front shaping has enabled control of light propagation inside linear media to focus and image through scattering objects. In particular, light propagation in multimode fibers comprises complex intermodal interactions and rich spatiotemporal dynamics. Control of physical phenomena in multimode fibers and its applications is in its infancy, opening opportunities to take advantage of complex mode interactions. Various embodiments of the present technology provide wave-front shaping for controlling nonlinear phenomena in multimode fibers. Using a spatial light modulator at the fiber's input and a genetic algorithm optimization, some embodiments control a highly nonlinear stimulated Raman scattering cascade and its interplay with four wave mixing via a flexible implicit control on the superposition of modes that are coupled into the fiber.

Provided is a light shaping device including: an intensity modulation unit that modulates a spectrum intensity of an optical pulse that is input light, and outputs the optical pulse of which a temporal width is narrowed as output light. The intensity modulation unit modulates the spectrum intensity of the optical pulse with a mask expressed by a starting end wavelength from a central wavelength of the input light and a wavelength width.

In some implementations, an electrical drive circuit may generate a rectangular optical pulse using cathode pre-charge and cathode-pull compensation. The electrical drive circuit may include an anode and a cathode to connect an optical load, a switch, a first source connected between the anode and a ground, a rectifier connected between the cathode and the switch, a capacitor connected in parallel with the rectifier, a second source connected to the ground, and an inductor connected between the switch and the second source. In some implementations, when the switch is closed and the optical load is connected, a first current is provided to the optical load through the first source, the rectifier, and the switch, and a second current is provided to the optical load through the first source, the capacitor, and the switch, where a rise time of the first current complements a fall time of the second current.

In some implementations, an electrical drive circuit may generate a rectangular optical pulse using cathode pre-charge and cathode-pull compensation. The electrical drive circuit may include an anode and a cathode to connect an optical load, a switch, a first source connected between the anode and a ground, a rectifier connected between the cathode and the switch, a capacitor connected in parallel with the rectifier, a second source connected to the ground, and an inductor connected between the switch and the second source. In some implementations, when the switch is closed and the optical load is connected, a first current is provided to the optical load through the first source, the rectifier, and the switch, and a second current is provided to the optical load through the first source, the capacitor, and the switch, where a rise time of the first current complements a fall time of the second current.

A laser pulse shaping device and method, a pulse shaper, and an optical system are provided. The laser pulse shaping device includes a pulse shaper provided in an optical path connected to a laser source, a laser detection device provided at an actual position of a target of a laser pulse, and the laser source configured to generate the laser pulse, which is transmitted to the target through the optical path. The laser detection device is configured to measure and send an optical parameter of the laser pulse transmitted to the target to the control device. The control device is configured to calculate a phase compensation parameter according to the optical parameter and control the pulse shaper to compensate a phase of the laser pulse transmitted through the optical path according to the phase compensation parameter, such that the optical parameter of the laser pulse reaches a target value.

A laser pulse shaping device and method, a pulse shaper, and an optical system are provided. The laser pulse shaping device includes a pulse shaper provided in an optical path connected to a laser source, a laser detection device provided at an actual position of a target of a laser pulse, and the laser source configured to generate the laser pulse, which is transmitted to the target through the optical path. The laser detection device is configured to measure and send an optical parameter of the laser pulse transmitted to the target to the control device. The control device is configured to calculate a phase compensation parameter according to the optical parameter and control the pulse shaper to compensate a phase of the laser pulse transmitted through the optical path according to the phase compensation parameter, such that the optical parameter of the laser pulse reaches a target value.

A pulse configurable laser unit is an environmentally stable, mechanically robust, and maintenance-free ultrafast laser source for low-energy industrial, medical and analytical applications. The key features of the laser unit are a reliable, self-starting fiber oscillator and an integrated programmable pulse shaper. The combination of these components allows taking full advantage of the laser's broad bandwidth ultrashort pulse duration and arbitrary waveform generation via spectral phase manipulation. The source can routinely deliver near-TL, sub-60 fs pulses with megawatt-level peak power. The output pulse dispersion can be tuned to pre-compensate phase distortions down the line as well as to optimize the pulse profile for a specific application.

A shaping encoder capable of improving the performance of PCS in nonlinear optical channels by performing the shaping in two or more stages. In an example embodiment, a first stage employs a shaping code of a relatively short block length, which is typically beneficial for nonlinear optical channels but may cause a significant penalty in the energy efficiency. A second stage then employs a shaping code of a much larger block length, which significantly reduces or erases the penalty associated with the short block length of the first stage while providing an additional benefit of good performance in substantially linear optical channels. In at least some embodiments, the shaping encoder may have relatively low circuit-implementation complexity and/or relatively low cost and provide relatively high energy efficiency and relatively high shaping gain for a variety of optical channels, including but not limited to the legacy dispersion-managed fiber-optic links.