NLS-Glossary

Laser light is different from ordinary light. We need to use laser to produce laser light. In the normal state, most of the atoms in the laser are in stable low energy level E1. Under the action of appropriate frequency of external light, the atoms in low energy level absorb photon energy to excite and transition to high energy level E2. The photon energy E= h V, where h is the Planck constant and V is the photon frequency. On the contrary, when the frequency of light is V, the atom in level E2 will jump to the low energy level to release energy and emit light, which is called stimulated radiation. First of all, the laser makes the atoms of the working materials abnormally in the high-energy level (i.e. inversion distribution of the particle number ), which can make the stimulated radiation process dominant, so that the induced light with the frequency of V can be enhanced, and the large stimulated radiation light can be produced through the avalanche amplification of the parallel reflector, which is called laser light for short.

is a band of energies for the electron in a semiconductor where it can gain energy from an applied field and drift and thereby contribute to electrical conduction. The electron in the conduction band behaves as of were a "free" particle with an effective mass, ${m^{*}}_e$

is a layer with a wider bandgap than the active layer, and adjacent to it, to confine the injected minority carriers to the active layer.                                                                            

Axicons are used to transform the collimated light into a ring or to create an approximation of a Bessel beam.                                                                                                           

is a mechanical coupling component (frequently at the end of an optical fiber cable) that allows two fibers to be easily aligned and coupled together end-to-end as close as possible. is a mechanical coupling component (frequently at the end of an optical fiber cable) that allows two fibers to be easily aligned and coupled together end-to-end as close as possible. A connector can also couple a fiber to an emitter or a detector. Insertion loss of a connector is usually higher than that of a splice.

Having no intercharacter spaces. In a continuous barcode, the end of one character is indicated by the beginning of the next, with no gap between.