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The semiconductor industry is the core industry of the information age. As a key link in the semiconductor industry, wafer fabrication plays a key role in its development. In the testing stage of the wafer, each die of the wafer is detected and marked, and a wafer map with a certain spatial pattern can be formed. The analysis and classification of these spatial patterns can identify the cause of wafer defects, thereby improving production yield. However, as wafer size increases, line widths become smaller, etc., the probability of a mixed defect mode wafer pattern increases. Moreover, the mixed defect mode wafer map is more difficult to identify and classify than the single defect mode wafer map. Therefore, this paper proposes an improved deep convolutional neural network (DCNN) structure model for the recognition and classification of mixed defect pattern wafer maps. From the perspective of increasing the width of the DCNN, the improved network structure can avoid problems such as over-fitting and limited extraction of features due to the continuous deepening of the DCNN. The network is called Multi-Path DCNN (MP-DCNN) structure. The experimental results show that the proposed Multi-Path DCNN structure has better performance and higher classification accuracy than existing methods. [ABSTRACT FROM AUTHOR]

Laser pulse amplification by a high-pressure CO2 amplifier in the long-wave infrared (LWIR) spectral range is a feasible technology for strong-field physics research. Crystals such as ZnGeP2 (ZGP) have high nonlinear coefficients and transmittance in the LWIR region, with spectral widths of generated pulses closely matching the gain spectrum of high-pressure CO2 amplifiers. Therefore, ZGP optical parametric oscillation (OPO) may allow higher-efficiency energy extraction in amplifiers, improving the output characteristics of LWIR amplification systems. In this study, the gain measurement of ZGP OPO pulses amplified by a high-pressure CO2 amplifier was carried out for the first time. Single-detector acquisition was utilized to achieve a unified sensor responsivity, and a laser signal-triggered function generator was used to synchronize the seed pulse and amplifier. Six-pass amplification was performed successively, yielding an amplification factor of 4.5 for the peak power and a maximum coefficient of 0.42% cm−1 for the small-signal gain. The gain and loss effect during small-signal amplification were discussed. The potential capability of acquiring ultra-short pulses with ZGP OPO pulses was also explored with the FFT function of MATLAB software. [ABSTRACT FROM AUTHOR]

Optical parametric oscillation (OPO) or optical parametric amplification (OPA) systems offer significant potential for generating high-energy, narrow-pulse laser output, finding applications across various domains. To achieve efficient amplification in cascade with amplifiers, precise frequency domain matching between OPO/OPA systems and amplifiers is imperative. Therefore, preliminary simulation and computation of the spectral characteristics of OPO/OPA systems are of paramount importance in the early stages of experimentation. Currently, the calculation of OPO/OPA output spectrum characteristics is limited to estimating the influence of pump light characteristics on output spectrum linewidth, a consideration that remains incomplete. This paper presents a comprehensive computational approach that takes into account the impact of four crucial factors on the output spectrum characteristics: pump light linewidth, pump light divergence angle, the walk-off effect, and the absorption loss of the crystal. This method finely characterizes the features of the output spectrum. The results obtained through the proposed approach align well with experimental results, underscoring its effectiveness. This study aims to obtain the output spectrum characteristics of BaGa4Se7 OPO/OPA through calculations to provide theoretical guidance for subsequent cascade amplification experiments. [ABSTRACT FROM AUTHOR]

A high-peak-power, widely tunable range long-wave infrared optical parametric oscillator (OPO) based on the BaGa 4 Se 7 (BGSe) crystal is demonstrated in this Letter. Pumped by a 1064 nm Nd:YAG laser, a high-peak-power of 0.15 MW was achieved at 9.8 µm with a pulse width of 5.0 ns. At 11.0 µm, a high beam quality of M 2 x = 4.1 and M 2 y = 3.3 was achieved. By rotating the BGSe crystal, a broad tuning range of 6.7-13.9 µm was realized. Furthermore, a theoretical analysis was conducted to elucidate the reasons behind the improvement in beam quality in the x-direction as the wavelength of the idler wave increases.