4 results about "Picosecond pulsed laser" patented technology

The application discloses a wide-band micro-region semiconductor photocurrent imaging system and method, and belongs to the technical field of semiconductor testing. The system comprises a temperature adjusting module, a picosecond pulse laser output module, an optical chopper, a microscopic imaging module, an electric piezoelectric displacement table and a lock-in amplifier. The temperature adjusting module is used for adjusting the temperature of a semiconductor device to be tested to 4K to 296K. The picosecond pulse laser output module is used for outputting a pulse laser beam in a wave band of 430nm to 2000nm. The optical chopper is used for modulating the laser beam into an optical pulse signal with a fixed modulation frequency. The lock-in amplifier is used for applying a bias voltage to the semiconductor device to be tested and collecting a photocurrent signal under the fixed modulation frequency. The electric piezoelectric displacement table is used for moving the semiconductor device to be tested point by point under a low-temperature environment. The microscopic imaging module is used for synchronously acquiring a surface topography image and constructing a photocurrent spatial distribution map. The application solves the technical problem that the current technology cannot simultaneously realize multi-wavelength excitation, weak signal extraction and micro-region spatial resolution imaging under an extremely low-temperature environment.

This invention relates to an isotropic three-dimensional super-resolution imaging method using a single objective lens, comprising the following steps: outputting a linearly polarized excitation beam through a picosecond pulsed laser and an outputting a linearly polarized loss beam through a nanosecond pulsed laser; adjusting the polarization direction and power of the excitation and loss beams using a half-wave plate and a polarizing beam splitter; incident the loss beam onto a spatial light modulator; modulating the light field by loading a preset phase diagram to generate three focal points with different topological charges, axial positions, and energy distributions; and modulating the polarization state of the focal points using a high-order vortex phase delay plate to separate the loss beams with different polarization components. This invention achieves an imaging resolution of less than 100 nm in both the lateral and axial directions, with similar lateral and axial resolution performance. In three-dimensional super-resolution imaging, it can accurately reflect the true three-dimensional structure of an object. The imaging resolution is directly proportional to the intensity of the loss beam; the stronger the loss beam intensity, the higher the three-dimensional imaging resolution.

The application relates to the technical field of nanomaterial preparation, in particular to a method for preparing Cu@Ag particles by laser, which comprises the following steps: S1, preparing a solution: dissolving a copper precursor in a solvent to obtain a copper precursor solution, and dissolving a silver precursor in a solvent to obtain a silver precursor solution; S2, irradiating the copper precursor solution by using a femtosecond pulse laser to generate nano-copper particle cores through reduction; S3, adding the silver precursor solution into the liquid phase environment containing the nano-copper particle cores, adjusting the wavelength parameter of the picosecond pulse laser to the surface of the nano-copper particle cores to realize laser energy focusing, irradiating the solution by using the picosecond pulse laser, allowing silver ions to be reduced and deposited on the surface of the nano-copper particle cores to form a silver shell, and thus obtaining Cu@Ag particles, so that the problems that the existing chemical reduction method is not environmentally friendly and it is difficult to accurately control the generation sequence of the core and the shell are solved.

A picosecond pulse nonlinear compression device based on a multi-pass cell achieves the advantages of high energy, compactness, and low cost, realizing femtosecond-level pulsed lasers at kilohertz repetition rates. A picosecond pulsed fiber laser generates stable mode-locked picosecond pulses with repetition rates of tens of megahertz. These pulses are injected into a solid-state regenerative amplifier via a fiber coupler, selectively amplifying the output signal to generate millijoule-level picosecond pulses with kilohertz repetition rates. The pulses then enter a mode matching module, which matches the mode of the incident laser with the eigenmode of the MPC cavity. Afterward, the pulses are injected into a spectral broadening module, which is filled with a nonlinear medium liquid to broaden the incident laser spectrum. Finally, the pulses are injected through convex mirrors into a chirp compensation module, which includes multiple pairs of parallel chirped mirrors to compensate for dispersion in the broadened pulsed laser spectrum.