Semiconductor lasers are used by many manufacturers in the market, so many people will mistakenly think that laser diodes and semiconductor lasers are one product, so are they really one product? Today, Xiaobian will give you a brief introduction.

In recent years, with the rapid development of China's laser industry, the related topics of "laser diode" and "semiconductor laser" have gradually come into public view. However, many readers and practitioners find that these two concepts are often mixed up, and some even think that they are the same thing. So, what is the difference between a laser diode and a semiconductor laser? Can I draw an equal sign? This is not only an academic discussion, but also an urgent problem to be clarified in industrial practice.

First, the macro concept of semiconductor laser

Semiconductor laser, as its name implies, is a laser that uses semiconductor material as working medium and realizes optical amplification through stimulated radiation principle. It is different from gas lasers, solid-state lasers, fiber lasers and other types, but uses the energy released by the recombination of electrons and holes in semiconductor chips to generate coherent light.

The biggest characteristics of this kind of laser are small size, high efficiency, low driving current and direct electro-optical conversion ability. Because of this, semiconductor lasers are called "the heart of modern optical industry" and are widely used in optical communication, industrial manufacturing, medical diagnosis and treatment, scientific research experiments and consumer electronics.

In the classification system, semiconductor lasers are not limited to one device form, but include multiple branches:

Edge-Emitting Laser Diode (LD)

Vertical cavity surface emitting laser (VCSEL)

Quantum cascade laser (QCL)

Distributed feedback laser (DFB Laser)

It can be seen that "semiconductor laser" is a macroscopic set concept.

Second, the device characteristics of laser diode

Different from the macro concept, laser diode refers to a specific semiconductor laser device based on diode structure. It usually adopts PN junction or quantum well structure, and the number of particles is reversed under the action of forward current, thus realizing stimulated radiation.

In appearance, the common packaging forms of laser diodes include TO-Can metal package, C-Mount ceramic package, Butterfly Package, etc., which is convenient for installation and heat dissipation. Because of its small size and convenient driving, laser diode is the most widely used semiconductor laser category with the largest shipment.

Typical applications of laser diodes include:

Laser printer and scanner, optical fiber communication transceiver module, laser ranging and laser radar, medical beauty equipment, laser projection and display, consumer laser pen, stage lighting.

It can be said that in daily life and industrial production, the most common semiconductor laser is actually a laser diode.

Third, the relationship between them: subordination and tolerance

In academia and industry, it is generally believed that:

Laser diode belongs to a branch of semiconductor laser.

Semiconductor laser is an upper concept, and laser diode is the most common and mature realization form.

All laser diodes are semiconductor lasers, but not all semiconductor lasers can be called laser diodes.

For example, VCSEL is a vertical cavity surface emitting laser, which also belongs to semiconductor laser, but its structure is different from that of diode, so it cannot be directly called "laser diode". The quantum cascade laser works in the mid-infrared band, and its luminescence mechanism is based on the electronic transition between energy bands, which is also different from the traditional diode structure.

Fourth, why are they often mixed?

Since there are differences between the two, why are they often confused in actual communication? The main reasons are as follows:

1. Reasons for historical evolution

In the early stage of the development of semiconductor lasers, laser diodes were the first to be successfully developed and industrialized. Therefore, for a long time, "semiconductor laser" is almost synonymous with "laser diode".

2. Reasons for market application

At present, most of the shipments and application scenarios of semiconductor lasers in the world come from laser diodes, which makes the public's understanding of "laser diodes" more intuitive and popular.

3. Reasons for expressing habits

In news reports, market promotion and popular science articles, people are more accustomed to using "laser diode" to refer to all semiconductor lasers, which is easy to cause conceptual ambiguity.

V. Enlightenment to industrial development

Clarifying the relationship between "laser diode" and "semiconductor laser" is not only an academic norm, but also the need of industrial development.

For researchers, accurate use of terminology is helpful for academic communication and avoids confusion of technical concepts.

For enterprises, a clear product category is helpful to accurately locate the market and promote technological innovation.

For users, understanding the basic differences is helpful to choose and apply products reasonably and improve the use effect.

In the future, with the increasing application of VCSEL in 3D sensing and quantum cascade lasers in gas detection and security, the family of semiconductor lasers will become more and more abundant. If we still only use the word "laser diode" to summarize, it is obviously not enough to cover the whole picture.

The relationship between laser diode and semiconductor laser can be summarized in one sentence: laser diode is a kind of semiconductor laser, and semiconductor laser has a wider range.

Today, with the continuous progress of science and technology, semiconductor lasers are entering thousands of industries at an unprecedented speed, playing an increasingly important role from intelligent manufacturing to life and health, from communication interconnection to national defense security. An accurate understanding of related concepts will help the whole society to better grasp the pulse of the industry and promote the independent, controllable and high-quality development of laser technology in China.