Semiconductor laser diodes also refer to semiconductor lasers or laser diodes. A semiconductor laser diode (LD) is a laser used in conjunction with optical fibers to construct optical communication systems. It can be directly used as a light source for optical communication, and can also be used as a pump source for lasers and amplifiers. It has a very important position in the field of laser engineering research. It has the characteristics of semiconductor devices: small size, simple structure, high efficiency, and direct modulation, but the output power, monochromaticity and directivity are not as good as other lasers.
According to wavelength and application, semiconductor lasers can be roughly divided into two categories: short-wavelength and long-wavelength lasers. Short-wavelength lasers include lasers with emission wavelengths ranging from 390 nanometers to 950 nanometers, and are mainly used in optical information and display applications such as optical drives, laser printers, barcode machines, scanners, and indicators. Long-wavelength lasers cover lasers with emission wavelengths from 980 nanometers to 1550 nanometers, which are mainly used for optical fiber communication.
If classified by the wavelength of the laser diode and the power of operation, it can be subdivided into the following four categories from short wavelength to long wavelength.
Classification of semiconductor laser diodes
A.390~550nm: Laser diodes in this band can be made of two series of materials: indium gallium nitride/indium gallium nitride/aluminum oxide or zinc selenide. The light-emitting wavelengths are about 390-440 nanometers and 520 nanometers, respectively. The most widely used application is in ultra-high-density storage systems, such as high-resolution printers or high-density DVD drives.
B.635~670nm: Laser diodes in this band are mainly made of AlInGaP/InGaP/GaAs materials. Low operating power laser diodes below 5 mW are mainly used in barcode readers, metrology alignment, laser pointers, and read-only optical information access systems. Such as: DVD-ROM drive or digital video player applications. Medium operating power laser diodes of around 30 mW are used in rewritable access systems such as DVD-R and DVD-RW burners. Laser diodes with operating powers above 100 mW are used in laser printers, solid-state laser excitation sources, and in medicine.
C.750~950nm: Laser diodes in this band are mainly made of AlGaAs/GaAs materials. 780nm laser diodes below 5 mW are the earliest mass-produced laser diodes, and are widely used in CD-ROM drives, CD turntables, CD game machines and other commodities. For mid-level operating power of 10mW to 1W, 30mW 780nm laser diodes are used in rewritable access systems such as CD-R burners, rewritable micro-drives. 500mW to 1W 808nm laser diodes are often used as excitation sources for NdYAG lasers for special effects on stage performances. High-power laser diodes above 1 watt are used to excite high-power solid-state lasers for material processing, or for medical treatment, digital printing, art performances, etc.
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