Optical waveguide device and harmonic generation device including same

Abstract

The invention provides an optical waveguide device, which comprises one or more optical waveguide devices provided with ridge-shaped notches; and the one or more optical waveguide devices are arranged on the substrate. According to the invention, pulse compression and higher harmonic generation are simultaneously realized in a chip integrated optical waveguide, and the waveguide structure is very compact, so that the size of the device is greatly reduced, and a desktop light source can be integrated into a chip type. Compared with a photonic crystal fiber, the chip-integrated optical waveguide has more excellent dispersion and nonlinear regulation and control capability and stronger light field constraint, and is more suitable for large-scale integrated development; compared with a device in a free space, the focusing limitation of a laser and gas action area is avoided, the light and gas interaction efficiency is improved, and the laser divergence phenomenon caused by plasmas is avoided.

Description

technical field [0001] The present invention generally relates to the technical field of integrated photonics, and in particular, to an optical waveguide device, a high-order harmonic generating device including the same, and a method for generating high-order harmonics. Background technique [0002] The generation technology of Extreme Ultraviolet (EUV) and even Soft X-ray (SXR) has received great attention in recent years, especially the use of High Order Harmonic Generation (HHG) to manufacture desktops type (table-top) extreme ultraviolet or soft X-ray light source. This process requires ultrashort pulses of single optical period or even sub-optical period with extremely high peak intensities. Existing lasers cannot directly provide ultra-short pulses with extremely high peak intensity, and need to be completed in two separate parts. First, pulse compression is performed to obtain ultra-short pulses with a duration of a single optical period or even a sub-optical period...

AI Technical Summary

Problems solved by technology

like figure 1 As shown, the pump energy of the pulse compressor in free space can be as high as several millijoules, but the nonlinear effect is large at high energy, which will lead to the loss of pulse energy

At the same time, in order to realize the pump energy of several millijoules, multi-stage amplifiers are required for optical amplification, and equipment of the order of meters is often required, which greatly increases the complexity

like figure 2 As shown, pulse compression can also be realized in photonic crystal fiber. The principle is to first generate supercontinuum and then perform chirp compensation, or directly realize pulse compression through high-order soliton compression, which utilizes the relatively mature dispersion and nonlinearity of photonic crystal fiber. Linear characteristics, but photonic crystal fiber is difficult to manufacture, and limited by the structure, material damage threshold, etc., the pump energy cannot be too high, usually in the order of micro-joules, which limits the peak intensity after pulse compression (that is, the effective mode field area peak power within), but also has disadvantages such as multi-mode interference

[0004] In the process of high-order harmonic generation, the interaction between the intense pulsed laser beam and the gas is usually achieved through a gas pump or a gas nozzle in free space. The flow is limited to a small area of ​​action, and the excessive free electrons generated by ionization will cause phase mismatch and laser divergence effects; while the hollow photonic crystal fiber controls the gas pressure at both ends of the fiber, and the interaction area between the laser and the gas Confined inside the optical fiber, the optical direction and the gas flow direction are usually the same, and the generated high-order harmonics cannot be separated from the input laser. It needs to be filtered by subsequent metal sheets or grating selective transmission to obtain extreme ultraviolet and soft X-rays. The intensity and phase of the laser Small disturbances will affect the interaction between light and gas, and the photon conversion efficiency is low

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