Laser exhibition technology has been widely used in the virtual environment of exhibitions and shows, as well as in the physical conference and exhibition centers. However, the speckle issue due to the high coherence of laser sources has caused harmful impacts on image quality, which is one of the obstacles to exhibition effects. In this paper, we design a compact Nd:YAG/PPMgLN laser module at 561.5 nm and use two different types of big-core multi-mode fibers to lower the spatial coherence. According to our experiment, the speckle contrasts relating to these two types reduce to 7.9% and 4.1%, respectively. The results of this paper contribute to improving the application effects of key optical components in the exhibitions. Only in this way can we provide technical supports and service guarantee for the development of the exhibition activities, and an immersive interactive experience for the audiences.

A dual-wavelength continuous-wave (CW) and passively Q-switched alexandrite laser based on a MoS2 saturable absorber (SA) operating at 736.7 nm and 752.8 nm with a simple and compact 18 mm plano–plano resonator is reported. In the CW mode, the output power is 1014 mW at the linear-polarized pump power of 5.44 W, with a slope efficiency of 28.7%. In the pulsed operation, the narrowest pulse width and the maximal peak power are 154 ns and 10.6 W, respectively. This laser can be used to generate 8.71 THz-wave light based on a suitable nonlinear optical crystal.

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In order to improve the light extraction efficiency (LEE) of a plane AlGaAs-based LED (Device A), three different surface periodic micron-scale arrays, micron pillar (Device B), micron truncated cone (Device C) and micron cone (Device D), are prepared by the conventional ultra-violet (UV) lithography. The morphology of the three devices B -D is characterized by a scanning electron microscopy (SEM). The periodic array structures improve the photon escape probabilities. In comparison to the Device A, the light output powers (LOPs) of the Devices B -D increase 54.0%, 145.5% and 157.2% at an injection current of 500 mA, respectively. Luminous uniformity of the periodic micron-scale array LEDs is better. Moreover, we use the Monte Carlo ray-tracing method to simulate the LEE of the four devices.