What are the types of semiconductor lasers?

What are the types of semiconductor lasers?

Semiconductor lasers have extremely wide-ranging applications, with different classification methods depending on their types. Let Songsheng Optoelectronics introduce the common classification of semiconductor lasers - come and learn about them!

Classification by Active Medium

GaAs Semiconductor Homojunction Laser Structure Diagram

Homojunction semiconductor lasers: These feature a simple structure where the active region and adjacent confinement layers are made of the same semiconductor material. However, they suffer from drawbacks such as low efficiency and high threshold current, resulting in limited practical applications today. Early-developed semiconductor lasers with simple structures typically belonged to this homojunction type.

Heterojunction semiconductor lasers

Single heterojunction semiconductor lasers: Composed of two semiconductor materials with different bandgap energies forming one heterojunction. This structure provides improved injection efficiency and carrier confinement compared to homojunction lasers, leading to enhanced performance characteristics.

InGaAsP Double Heterojunction Stripe Laser Diagram

Double heterojunction semiconductor lasers: Featuring two heterojunctions, this structure provides superior carrier and optical field confinement, resulting in significantly reduced threshold current and enhanced efficiency. As the most widely adopted semiconductor laser configuration today, it is commonly used in fiber optic communications, laser printing, and other applications. Most semiconductor lasers employed in these fields utilize the double heterojunction design.

Classification by Operation Mode

Continuous Wave (CW) Semiconductor Lasers:

Capable of delivering continuous laser output with relatively stable power. Widely used in applications requiring sustained laser emission, such as laser communications and continuous welding/cutting in laser processing. For instance, in long-distance fiber optic communication systems, CW semiconductor lasers serve as light sources to reliably transmit optical signals.

Pulsed Semiconductor Lasers:
Emit laser output in pulsed form with adjustable parameters including pulse width and repetition rate. Characterized by high peak power, these lasers are ideal for laser ranging, LiDAR, laser marking, and similar applications. A typical example includes laser rangefinders that utilize pulsed semiconductor lasers to emit short laser pulses, calculating distances by measuring the time-of-flight to targets.

Classification by Output Wavelength

Constant Temperature Blue Light Galvanometer Soldering System Diagram

Short-wavelength Semiconductor Lasers:
Primarily include ultraviolet (UV), blue, and green semiconductor lasers. UV semiconductor lasers find applications in lithography, biological detection, and high-density data storage. Blue lasers are utilized in Blu-ray disc storage and laser display technologies, while green lasers are commonly employed for laser shows and laser projection applications.

Medium-wavelength Semiconductor Lasers:
Typically represented by near-infrared devices with wavelength ranges of 0.7-2μm, including common 808nm, 980nm, and 1064nm wavelength lasers. These lasers have extensive applications in fiber optic communications, laser soldering, plastic welding, and medical laser systems. For instance, 980nm semiconductor lasers frequently serve as pump sources for laser soldering and plastic welding processes.

Songsheng Optoelectronics 976/980nm Water/Air-Cooled Temperature-Stabilized Semiconductor Laser Diagram

Songsheng Optoelectronics' independently developed 976/980nm constant-temperature semiconductor laser is specifically designed for laser soldering and plastic welding applications. Featuring a PID algorithm with rapid response (15μs), it significantly reduces the risk of solder joint burnout. The laser incorporates a closed-loop temperature feedback system that continuously monitors and regulates the heating point temperature via infrared sensors, maintaining a stable preset temperature during welding. Available in air-cooled or water-cooled configurations to meet customer requirements, with standard output power options ranging from 10W to 2000W (including 10W, 100W, 200W, 300W, 500W, 1000W, and 2000W).

Long-wavelength semiconductor lasers:
With wavelengths typically exceeding 2μm, these are primarily used in gas sensing, environmental monitoring, and medical diagnostics. Their specific absorption characteristics for certain gases enable precise detection of gas concentrations and composition analysis.

Classification by Application Fields

Optical Communication Semiconductor Lasers:
Used in fiber optic communication systems, these lasers require high output power stability, narrow linewidth, and low noise. Representative types include Distributed Feedback (DFB) lasers and Distributed Bragg Reflector (DBR) lasers, which provide stable single longitudinal mode output to ensure high-quality and high-speed optical communications.

Optical Storage Semiconductor Lasers:
Employed in optical disc storage devices for read/write operations in CDs, DVDs, Blu-ray discs, etc. Different disc types demand specific laser wavelengths and power levels:

• CDs utilize 780nm wavelength lasers

• DVDs require 650nm wavelength lasers

• Blu-ray discs use 405nm wavelength lasers

Songsheng Optoelectronics Constant-Temperature Laser Soldering System Module Composition Diagram

Laser Processing Semiconductor Lasers: Require high output power to meet material processing needs such as cutting, welding, and drilling. Typically adopting array structures to enhance output power, they can be used for processing various materials including metals and plastics.

Medical Semiconductor Lasers: Can be applied in medical fields such as laser surgery, laser therapy, and cosmetic treatments. Different medical applications have specific requirements for laser wavelength, power, and pulse characteristics. For example, 635nm semiconductor lasers can be used for photodynamic therapy, while 810nm lasers are suitable for laser hair removal.

Laser Display Semiconductor Lasers: Used in display devices like laser TVs and laser projectors, requiring high brightness, excellent color performance, and uniformity. Full-color display is typically achieved by combining red, green, and blue primary color semiconductor lasers.