Laser Diode Selection

Laser diodes are the hidden champions of modern laser technology. Laser diodes are everywhere, from simple laser Pointers to complex quantum communication satellites. It has excellent efficiency, compact structure, numerous types, many people have considered to use laser diode in their own products, facing a variety of laser diode diodes, engineers how to choose?

We can determine the required laser diode through the following four steps.

Step 1: Convert application requirements into laser parameters

The first step is to determine a set of parameters based on the application. It is necessary to construct a laser interferometer for surface profile analysis or velocity measurement.

To construct a laser interferometer, we need a laser diode with a coherent length of 1 to 10 m and stable at temperature variations (<0.1 nm/K). The power of the Collimated Gaussian beam should be > 80mW.The detectors used are based on silicon (wavelength <1100nm).

Using the coherence length, we can calculate the line width δ ν =C /πL (δ ν is the bandwidth (or line width), C the speed of light, and L the coherence length).

Similarly, we can use formulas to calculate the band pass (sensors used to detect laser signals usually use interference filters to block the interfering ambient light), the beam quality and beam profile (the intensity distribution of the laser beam), and the brightness of the laser source (a measure of its output power and beam quality).

Step 2: Select a laser type

Step 2: Describe the type of laser in detail. Because there are so many options, we need to weigh them.

The appropriate parameters for the application need to be marked. In terms of wavelength tolerance, there is no restriction, and its weight is zero. In terms of line width, the calculation range should be between 10 and 100 MHz.

Next, the other parameters are processed in the same way. In the last line, we multiply all the marks by the weights. Finally, we get the type of laser diode we're looking for.

Step 3: Select the laser material

The third step is to determine the wavelength, which is usually very important for applications.

The laser emission wavelength is limited to <1100 nm. This means that gallium nitride (GaN) or gallium arsenide (GaAs) laser diodes may be suitable for us. Typically, ultraviolet light (UV) solutions are more expensive than laser diodes in visible light (VIS) or near infrared (NIR), so the final chosen material can be labeled VIS-to-NIR.

Step 4: Make the final chart and start looking for suppliers

When you have all the parameters required for the applicable laser diode. We need to consider the following parameters:

(1) Operation mode. Continuous wave, pulse or modulation. This can have a huge impact on heat management and packaging styles. For Lowduty cycle pulsed or pulsed modulated laser diodes, there may be less waste heat and therefore a smaller package size.

Beam collimation (free space, integrated optical element or fiber tail). Much depends on the application of laser diodes.

(2) Encapsulation. Plane encapsulation or TO encapsulation. Overall size, compatibility with existing solutions, pin configuration. These are all factors to consider.

(3) Price. In industry, some common wavelength laser diodes are much cheaper than others.

Armed with the above data, you can start looking for laser diode suppliers who can use this data to understand your needs and provide possible solutions as soon as possible.

In addition, if your demand is an annual batch is tens or hundreds of thousands of laser diodes. You may want to consider becoming a strategic partner with a laser diode supplier, as custom laser diodes make mass production more assured.