A semiconductor laser is also called a laser diode (LD). In the 1980s, people absorbed the latest developments in semiconductor physics, using novel structures such as quantum wells (QW) and strained quantum wells (SL-QW), introducing refractive index modulated Bragg emitters and enhanced modulation Bragg emitters. The latest technology, as well as new crystal growth technology such as MBE, MOCVD and CBE, has enabled the new epitaxial growth process to accurately control crystal growth, achieve atomic layer thickness accuracy, and grow high quality quantum wells and strained quantum well materials. As a result, the threshold current of the LD produced is significantly reduced, the conversion efficiency is greatly improved, the output power is multiplied, and the service life is also significantly lengthened.
A low power LD
Small power LDs used in the field of information technology are developing very fast. For example, distributed feedback (DFB) and dynamic single-mode LD for optical fiber communication and optical switching systems, narrow linewidth tunable DFB-LD, visible light wavelengths for information processing technologies such as optical discs (eg, wavelengths of 670 nm, 650 nm, 630 nm) The red light to blue-green light) LD, quantum well surface emitting laser and ultrashort pulse LD have all been substantially developed. The development characteristics of these devices are: single-frequency narrow linewidth, high rate, tunable and short-wavelength and opto-electronic monolithic integration.
B high power LD
In 1983, the output power of a single LD with a wavelength of 800 nm exceeded 100 mW. By 1989, the LD of 0.1 mm strip width reached a continuous output of 3.7 W, while the 1 cm line array LD had reached 76 W output with a conversion efficiency of 39%. In 1992, Americans raised the index to a new level: 1cm linear array LD continuous wave output power of 121W, conversion efficiency of 45%. Now, many high-power LDs with output powers of 120W, 1500W, and 3kW are available. The rapid development of high-efficiency, high-power LDs and their arrays also provides strong conditions for the rapid development of fully-cured lasers, ie, semiconductor laser-pumped (LDP) solid-state lasers.
In recent years, in order to meet the needs of EDFA and EDFL, high-power LDs with a wavelength of 980 nm have also been greatly developed. Recently, fiber Bragg gratings have been used for frequency selective filtering to greatly improve the output stability and pump efficiency has been effectively improved.