Laser Diode Array (Bar)

Learn More About Laser Diode Arrays / Laser Diode Bars

In a laser diode array (bar), the individual emitting areas (emitters) lie side by side, separated by the non-emitting areas. These sets of emitting/non-emitting regions form the so-called active layer. Laser diode bars can have as many as 100 emitters and are typically 1 cm long. The number, the width, and the spacing of the emitters are dependent on the manufacturer and the optical performance required from the bar. The relative value of the emitting areas in the active layer with respect to the bar width is the filling factor (FF). Typical filling factors are 30 – 90%. The center-to-center distance between two adjacent emitters is the emitter pitch. Z is the propagation axis of the laser radiation. The propagation axis Y is the fast axis (FA) and the X axis is the slow axis (SA), referring to the rate of divergence. Therefore, these axes comprise the beam angle (divergence) in the two planes, XZ and YZ. Output powers are available in the order of 10W – >300W per bar. Laser diodes bars are available as unmounted laser diode bars or mounted in conductively or actively cooled packages.

Our Laser Diode Array (Bar) Products

Laser diode arrays (bars) and multimode laser diode stacks are available in unmounted laser diode bars or mounted in conductively or actively cooled packages. Multiple bars can be stacked in the horizontal or vertical direction to increase the output power.

We offer diode laser arrays (bars) and stacks in wavelengths ranging from 760nm-1470nm in several free-space and fiber-coupled packages. Furthermore, these diode lasers are available in CW operation with up to 400W output power & QCW operation with up to 500W output power.

Deeper Dive into Laser Diode Arrays (Bars)

Understanding Laser Diode Arrays

Most people reading this probably have a general understanding of the fact that the photons in a laser diode are generated by electron-hole recombination at the PN junction inside of the diode, and that the front and back facets of the diode serve as the optical resonator.  While this analysis of how a laser diode works is more than effective for gaining a basic understanding of its make-up, the ridge is a critical element is often left out of any fundamental discussion.  The ridge, as shown in the simulation below serves as a step-index waveguide ensuring that all of the light emitted from the PN junction is contained and traveling in the proper direction.  By adjusting the width of the ridge, an engineer can control various properties of the laser particularly the power, mode structure, and modulation speed (capacitance), making it one of the most important factors in a laser diodes design.

The vast majority of laser diodes only contain a single ridge (we call these single emitters), but for very high power laser applications it became helpful to create diode structures with multiple ridges in order to increase the total power output without increasing the total power density on the facet. This multi-ridge structure is what is known as a diode array or diode bar, and can contain as many as 100 emitters in a single structure, producing over 300 watts of power.   The figure below shows a typical structure of a laser diode array.

For even higher power applications these bars can be stacked and put into a single package capable of producing kilowatts of laser power.  In this case, microchannel cooling is often used in laser diode bar stacks due to a large amount of waste heat in a small area.  Laser Diode Bars and Stacks are available in several free space and fiber coupled packages.  Here at RPMC we offer a wide variety of high power diode stacks.  Depending on the output power and package cooling, these lasers can either be run in continuous wave (CW) or quasi-continuous wave (QCW) operation.

These high-power laser diode stacks are often used in applications ranging from materials processing such as welding, cutting, and cladding, to medical applications such as hair removal and ophthalmology to defense and military applications like directed energy weapons (DEW).

Laser Diode Bar Stress

In the past RPMC has taken a look at laser diode lifetime in both a white paper titled “How to Improve Laser Diode Lifetime! Advice and Precautions on Mounting,” and an application note called “Understanding Laser Diode Lifetime.”  Additionally, we have explored the fundamental material structure of laser diode bars in a blog post titled “Understanding Laser Diode Arrays” (discussed in the above section on this Laser Diode Array page).

In this application note, we plan to combine these two topics and look at one of the key factors that affect laser diode bar lifetime – stress and strains.  Despite the extreme power output of laser diode bars and stacks, which can exceed 2 kilowatts of power in quasi continuous wave (QCW) operation, the facet coating technology has improved to the point where it can handle intensities well over 20MW/cm² making catastrophic optical damage (COD) no longer a limiting factor.  With modern day diode bars, thermal management, mechanical stress, and material defects introduced by the mounting/packaging process are far more critical to their lifetime and performance.  For this reason, we are going to focus our attention on both intrinsic and extrinsic stress in the diode, and how each affects the performance and lifetime of the diode.

Read the full article here.

How Can We Help?

With over 25 years experience providing laser diode arrays / laser diode bars to OEM integrators working in various markets and applications, and 10s of thousands of units fielded, we have the experience to ensure you get the right product for the application. Working with RPMC ensures you are getting trusted advice from our knowledgeable and technical staff on a wide range of laser products.  RPMC and our manufacturers are willing and able to provide custom solutions for your unique application.

If you have any questions, or if you would like some assistance please Contact Us here. Furthermore, you can email us at info@rpmclasers.com to talk to a knowledgeable Product Manager.

Alternatively, use the filters on this page to assist in narrowing down the selection of laser diode arrays (bars) for sale. Finally, head to our Knowledge Center with our Lasers 101 page and Blogs, Whitepapers, and FAQ pages for further, in-depth reading.

Check out our Online Store: This page contains In-Stock products and an ever-changing assortment of various types of new lasers at marked-down/discount prices.