Laser chip diodes come in various types, including edge-emitting, vertical-cavity surface-emitting (VCSEL), single-mode, multi-mode, MOPA, double heterostructure, and quantum well diodes, each designed for specific performance and applications.

Edge-Emitting Diode Lasers

Edge-emitting diodes emit light parallel to the chip surface and are typically made from materials like gallium arsenide (GaAs), indium phosphide (InP), or gallium nitride (GaN) with a layered structure including an active p-n junction. They provide high optical power, ranging from milliwatts to several watts, and are widely used in telecommunications, optical storage, barcode scanning, and industrial laser systems .

Vertical-Cavity Surface-Emitting Lasers (VCSELs)

VCSELs emit light perpendicular to the chip surface. They feature a short optical cavity with distributed Bragg reflector (DBR) mirrors on both ends, and the active region is located between these mirrors. VCSELs are known for low threshold currents, high efficiency, and ease of integration into arrays, making them suitable for data communications, sensing, and optical interconnects .

Single-Mode and Multi-Mode Diodes

• Single-mode diodes have a narrow active region supporting only one optical mode, producing a highly focused, low-divergence beam with high coherence. They are ideal for fiber optic communication, spectroscopy, and precision sensing .
• Multi-mode diodes have a broader active region supporting multiple optical modes, resulting in higher output power but lower coherence. They are used in laser cutting, welding, printing, and illumination .

Master Oscillator Power Amplifier (MOPA) Diodes

MOPA diodes combine a single-mode oscillator with a multi-mode amplifier, increasing output power while maintaining spectral purity. They are commonly used in lidar, range finding, and medical imaging .

Double Heterostructure and Quantum Well Diodes

• Double heterostructure diodes have a three-layer structure where the active region is sandwiched between cladding layers, trapping light and carriers for high efficiency and lower operating current .
• Quantum well diodes feature an ultra-thin active layer that confines electrons and holes, enhancing light generation efficiency and beam quality. Multiple quantum wells can further improve performance, widely applied in advanced electronics, precision manufacturing, and high-speed marking .

Summary

Laser chip diodes are classified based on emission direction, mode structure, and semiconductor design. Choosing the right type depends on the required power, beam quality, coherence, and application, ranging from telecommunications and medical devices to industrial processing and optical sensing .