“…In this Special Issue on miniature optoelectronic resonators and oscillators, we include seven papers, covering different aspects related to oscillating-amplifying integrated fiber lasers (1), calibration method for the resolution of two-dimensional laser direct writing (2), algorithms for weld depth measurement in laser welding of copper (3), highly integrated cladding mode stripper array (4), quasi-continuous wave pulsed laser welding of copper lap joints using spatial beam oscillation (5), in-process analysis of melt pool fluctuations with scanning optical coherence tomography for laser welding of copper ( 6), and a real-time working method that improves process efficiency in high-power fiber laser systems (7).…”