Semiconductor lasers, principles

Shyh Wang, Principles and Characteristics of Integratable Active and Passive Optical Devices Shlomo Margalit and Amnon Yariv, Integrated Electronic and Photonic Devices Takaaki Mukai, Yoshihisa Yamamoto, and Tatsuya Kimura, Optical Amplification by Semiconductor Lasers... 

Semiconductor lasers have undergone a considerable metamorphosis during the past 30 years. They have grown and developed into a whole range of sophisticated opto-electronic devices. It is beyond the scope of this section to give a detailed description of the different semiconductor lasers, but we shall summarize the basic principles of this type of laser. 

Semiconductor optical amplifiers (SOA), also referred to as semiconductor laser amplifiers (SLA), are devices very similar to semiconductor lasers, which amplify light that is injected into the device. The principle behind the operation of a semiconductor optical amplifier is identical to that of other semiconductor lasers. It is the creation of a population inversion that allows stimulated emission and optical irr. As in a conventional semiconductor laser, the population inversion is achieved by injecting carriers by an electrical current into the active region, which subsequently recombine through spontaneous and stimulated emissioa... 

The general principle of operation of QCLs is depicted in Figure 4.19. Conventional semiconductor lasers (such as the diode lasers used CD-players and telecommunication applications and the lead-salt devices commonly used in the mid-lR) rely on electron-hole recombination across the doped... 

The basic principle of semiconductor lasers [5.113-5.117] may be summarized as follows. When an electric current is sent in the forward direction through a p-n semiconductor diode, the electrons and holes can recombine within the p-n junction and may emit the recombination energy in the form of EM radiation (Fig. 5.63). The linewidth of this spontaneous emission amounts to several cm and the wavelength is determined by the energy difference between the energy levels of electrons and holes, which is essentially determined by the band gap. The spectral range of spontaneous emission can therefore be varied within wide limits (about 0.4—40 xm) by the proper selection of the semiconductor material and its composition in binary compounds (Fig. 5.64). 

Basov (1922-2001) and Aleksandr Prokhorov (1916-2002), two Russian physicists who independently discovered how to produce continuous output, something that Townes was unable to do. The three were cited for fundamental work in the field of quantum electronics, which has led to the construction of oscillators and amplifiers based on the maser-laser principle [29]. Since that time, many different types of lasers were developed—gas, solid-state, fiber, semiconductor, dye, etc.— and they have found use in hundreds of applications in virtually every field of endeavor such as the military, industry, law enforcement, medicine, entertainment, and basic research [29]. 

In studies of the properties of semiconductor particles or corresponding colloidal solutions, the formation of intermediates needs to be measured. This is usually done by employing a laser flash apparatus, as has been commonly used in photochemistry for many decades. The principle is as follows. 

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