The Fundamentals of Semiconductor Lasers

What Is Semiconductor Lasers

A semiconductor laser, also known as a laser diode (LD), utilizes semiconductor material as the working material to generate excited emission. This type of laser has gained immense popularity due to its various advantages, including small size, light weight, reliable operation, low energy consumption, high efficiency, long service life, and fast modulation speed.Therefore, semiconductor lasers have been widely used in laser communication, optical storage, optical gyroscope, laser printing, laser medicine, laser ranging, LIDAR, automatic control, testing instruments and other fields.

Modes of Excitation

The excitation of semiconductor lasers occurs through three main modes: electrical injection, electron beam excitation, and optical pump excitation. These modes enable the efficient generation of excited emission and play a crucial role in the functioning of semiconductor lasers.

Types of Semiconductor Lasers

Semiconductor lasers are generally classified into three categories based on their junction structure: homogeneous junction lasers, single heterojunction lasers, and double heterojunction lasers. Homogeneous junction and single heterojunction lasers are primarily used as pulsed devices at room temperature, while double heterojunction lasers can operate continuously under the same conditions.

Applications of Semiconductor Lasers

Thanks to their exceptional properties, semiconductor lasers have found extensive applications in numerous fields, including:

• Laser communication
• Optical storage
• lOptical gyroscope
• Laser printing
• Laser medicine
• Laser ranging
• LIDAR
• Automatic control
• Detection instruments

Working Principle of Semiconductor Lasers

The working principle of a semiconductor laser relies on achieving particle number inversion of non-equilibrium carriers between the energy bands of semiconductor materials or between the energy bands of semiconductor materials and impurity energy levels. This inversion state leads to excited emission when a significant number of electrons combine with holes.

Types of Excitation

Semiconductor lasers employ three primary types of excitation:

• Electrical Injection: This mode involves injecting electrical current into the semiconductor material to achieve particle number inversion and generate excited emission.
• Electron Beam Excitation: In this mode, an electron beam is used to excite the semiconductor material and stimulate excited emission.
• Optical Pump Excitation: Here, the optoelectronic device uses an external laser as an optical pump to stimulate the emission of photons. This mode commonly employs n-type or p-type semiconductor single crystals as the working material.

Operating Wavelength of Semiconductor Optoelectronic Devices

The operating wavelength of semiconductor optoelectronic devices is dependent on the type of semiconductor material used. Semiconductor materials possess conduction and valence bands, with a forbidden band between them. When electrons absorb light energy and transition from the valence band to the conduction band, the light energy converts into electrical energy. The width of the material's band gap determines the operating wavelength of the optoelectronic device.More electronic components can be found in Joinwin Electronics, which provides solutions to a wide range of purchasing problems, customised requirements and eight million product reports in PDF format for download, electronic component distributors.

Conclusion

Double heterojunction electrically injected GaAs semiconductor lasers have proven to be highly efficient and versatile within the field of semiconductor lasers. With ongoing advancements and research, these lasers continue to pave the way for innovation in various industries.