定义：
包含二极管激光器，或者一些光学元件，冷却装置，电子器件等的模块。

激光二极管通常以激光二极管模块的形式应用，即包含一个或多个激光二极管的模块，大多数情况下还包括一些光学和电子学器件。这种模块比简单的激光二极管更易于使用，并且它们具有多个功能： 

1. 光束整形：一些光学元件（例如，包括准直透镜，微光学和失真的棱镜对）可以用于对输出光束进行整形，例如，可以得到很小发散角的近于圆形的光束。这种准直光束更易于在很长距离传输，并且耦合到光纤中的效率更高。 
2. 光纤耦合：有些激光二极管模块是光纤耦合的，即直接将产生光射进光纤中。 
3. 电子连接器：激光二极管模块不仅包含简单的连接到激光二极管上的插脚，还具有附加的电子回路器件，例如，保护激光二极管免受静电放电的损害或者过高的工作电压。可以直接利用一块电池或者非稳定的功率来工作。 
4. 冷却装置：高功率情况下，激光二极管模块需要冷却装置，例如，将金属表面安装在冷却器上。也可能包含一个热电冷却器，采用一个反馈系统来稳定二极管温度。这样可以得到更加稳定的输出波长和功率。 
5. 功率稳定：采用内部的反馈回路也可以稳定输出功率，需要采用一个控制光电二极管（通常在激光二极管内）。 
6. 脉冲产生：驱动电流变成脉冲形式来通过增益关联产生输出脉冲。采用这种方法可以得到纳秒甚至皮秒脉冲。 
7. 波长转换：存在绿色的激光二极管模块，其中采用了内置的倍频器。这种模块可能包含一个放大的单模激光二极管和一个非线性波导。 

激光二极管模块的应用包含光学元件的精确定位和排列，打印和成像系统，显示，条码扫描，光学数据存储，光学传感器，泵浦固态激光器，露天通讯和医学应用（例如，光动力学疗法，眼科学）。

还有激光笔，是激光二极管模块集成了电池，是一种手持装置。

Definition: modules containing diode lasers, and possibly also some optics, cooling devices, electrical elements, etc.

Laser diodes are often used in the form of laser diode modules, i.e. packages which contain one or several laser diodes, in most cases combined with some optics and electronics. Such modules are much easier to use than bare laser diodes, as they serve a number of functions, as explained in the following. The optical output is either into free space – typically as a collimated beam, through a connected fiber or with a fiber connector.

Beam Shaping

For a laser diode module with free-space output, some optics (e.g. consisting of collimating lenses, micro-optics, and anamorphic prism pairs) can be used to shape the output beam, e.g. in order to obtain an approximately circular (or sometimes elliptical) beam with small divergence. Such a collimated beam can be more easily transmitted over some distance and more efficiently coupled to an optical fiber.

Important parameters e.g. for collimated outputs are the beam radius and beam divergence angle in both directions, the beam quality factor M² and some measure for the beam pointing fluctuations (or the possible beam direction change during the warm-up time).

Other modules for specialized applications offer certain beam shapes, e.g. that of a line, a cross, an open circle, or a square.

Fiber Coupling

Some laser diode modules are fiber-coupled, i.e., directly launch the generated light into an optical fiber (“pig-tailed” laser diodes). For limited optical power, this may be a single-mode-fiber, which might even be polarization-maintaining, as the output is often linearly polarized. Otherwise, multimode fibers are common, and are the only option at high power levels.

Power and Wavelength Stabilization

The output power may be stabilized with an internal feedback loop with a monitor photodiode (often built into the actual laser diode). Some modules are very carefully stabilized to achieve a small relative intensity noise.

There are wavelength-stabilized modules, e.g. using passive stabilization with frequency-filtered optical feedback, or just temperature stabilization (see below). The output wavelength may drift somewhat more during the warm-up time after switching on the module.

Power Modulation

In some cases, the built-in electronics have an input for power modulation. Others are meant for continuous-wave operation with constant power only.

Pulse Generation

It is possible to obtain nanosecond or even picosecond light pulses from laser diode modules. For example, there are gain-switched modules with integrated driver electronics – which is important as very short electrical connections should be used for that mode of operation. In other cases, one uses quasi-continuous-wave operation with much longer pulse durations.

Wavelength Conversion

There are green laser diode modules with an internal frequency doubler. Such a module may contain an amplified single-mode laser diode and a nonlinear waveguide, for example.

Electrical Connections

A laser diode module may contain not only simple connections to the pins of the laser diode, but also additional electronic circuits, e.g. for protecting the laser diode against electrostatic discharge (ESD protection), wrong poling and too high operating voltages. Power stabilization (see above) and/or power monitoring is another possibility, also electronics for gain switching.

A module can often be operated directly with a battery or with an unstabilized power supply.

The module case may also provide effective shielding against external electromagnetic influences, which might otherwise affect the drive current and output power.

Cooling and Temperature Stabilization

For high powers, a laser diode module can facilitate the cooling, e.g. by offering a metallic surface which can easily be mounted on a cooler.

Temperature stabilization is also important for low-power diode modules, since the junction temperature influences the emission wavelength. A thermoelectric cooler (TEC) may also be included, often with a feedback system to stabilize the diode temperature. This leads to a more stable output wavelength and output power.

Applications

Applications of laser diode modules include precise pointing and alignment of optical elements, printing and imaging systems, displays, bar code scanning, optical data storage, optical sensors, pumping of solid-state lasers, free-space communications, and medical applications (e.g. photodynamic therapy, ophthalmology).

Many modules are used as OEM laser modules, i.e., integrated into larger devices by a manufacturer who does not want to deal with various details of the laser diodes.

There are also laser pointers, which can be considered as laser diode modules with integrated batteries, normally used as hand-held devices.