Multimode Diode Lasers, also known as broad area emitters, have a wider waveguide and emitting area that allows for higher output power. Due to the wider emitter, multi-mode laser diodes have a lower beam quality than single-mode lasers.
The spatial mode structure of a diode laser is determined by the ridge width of the waveguide, similarly as the core of a fiber-optic cable. For high power multimode laser diodes, the ridge widths are typically on the order of 100 microns or larger, which allows for a much larger volume of material to be actively involved in the lasing process and therefore generate higher laser powers. Additionally, this provides a larger surface area at the output facet reducing the intensity and decreasing the risk of catastrophic optical damage. Laser diodes with multiple modes are available from both single emitters and diode arrays and come in either free space or fiber coupled configurations.
Typically, a laser with an M2 value greater than 2 is regarded as ‘multimode.’
Our Multimode Laser Products
Here at RPMC Lasers, we offer a wide range of wavelengths from UV as low as 375 nm to LWIR up to 9.4 µm with multimode outputs, including wavelength stabilized bars and single emitters, QCLs, CW DPSS lasers, Gas Lasers, laser combiners, and more. These lasers are ideal for a diverse range of applications including fiber laser pumping, laser cladding, surface enhanced Raman spectroscopy (SERS), machine vision, and many more.
Deeper Dive into Multimode Lasers
Multimode vs Single-Mode Lasers for Raman Spectroscopy
Raman spectroscopy is one of the fastest growing and most diverse applications in all of laser spectroscopy. As a result, it can be rather challenging at times to sift through the wide-ranging laser options all being marketed for Raman spectroscopy. In this application note we will tackle one of the most common questions that arises when picking a laser for Raman spectroscopy; “Should I chose a single-spatial mode or multi-spatial mode laser for my application?” On the surface, this seems like a simple question since Raman is a nonlinear optical effect and therefore the tighter the beam can be focused the higher the conversion efficiency. Seemingly a single-mode laser would be preferable, but in practice there are other factors that can complicate the situation.
For some application such as laser pointers this elliptical beam shape is perfectly fine and as such only a single optic is necessary for culminating the output. This can be accomplished either by utilizing a cylindrical lens which reduces the divergence of the fast axis while allowing the slow axis to pass through unaffected or by using a single aspherical lens. For more advanced applications which require a circular beam cross cylindrical lenses where each lens is chosen to match the numerical aperture of the fast and slow axis can be used as shown in the figure below. While this approach does an excellent job of circularization it often results in a diamond-shaped beam profile due to amplified spontaneous emission, to further improve the beam quality, it is generally preferable to fiber couple the beam and then re-collimate the output. For single mode lasers the fiber acts as a spatial filter resulting in a perfect TEM00 output beam, and in the case of multi-mode lasers, the fiber acts as a homogenizer significantly reducing the hot spots and dark spots. All of the optical configurations discussed previously are used with single emitters, but the same principles can also be applied to multi-emitters where large cylindrical lenses or microlens arrays are often utilized.
In the previous blog post on this subject, we discussed that when machine vision is used for the inspection of small parts, laser lines and other shapes are typically achieved through the use of diffractive optical elements, which when used with single mode diode lasers can create a wide variety of geometric shapes and patterns. While these low power single mode lasers are typically sufficient for inspection of small parts on a production line, as the size requirements on the line continue to increase the use of multimode high-power lasers becomes a necessity. As a result, the higher power density becomes an issue for diffractive optics to handle as they are unable to shape multi-spatial mode lasers. As a result, to generate long lines from higher powered multi-mode laser diodes either galvanometric scanning mirrors or micro-optic arrays are required. While scanning mirrors can be somewhat effective at producing uniform laser lines, they suffer from reliability issues, especially in rugged environments, making them a less than ideal solution for deployable field systems. Micro-lens arrays, on the contrary, are a monolithic solution which can either be placed at the output of a fiber-optic cable or directly in front of the diode bar to exploit inherent astigmatism and produce flat top laser lines. In the previous blog, we showed the example of one such flat top laser source, the FocusFlux from Focuslight. It can create a high-power laser line at distances up to 3 meters from the source with fan angles as large as 110-degrees, making them ideal for inspecting larger objects and surfaces.
With over 25 years experience providing multimode lasers to researchers and OEM integrators working in various markets and applications, and 1000s 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 [email protected]to talk to a knowledgeable Product Manager.
Alternatively, use the filters on this page to assist in narrowing down the selection of multimode lasers for sale. Finally, head to our Knowledge Center with our Lasers 101 page and Blogs, Whitepapers, and FAQ pages for further, in-depth reading.
Finally, check out our Limited Supply – In Stock – Buy Now page: This page contains an ever-changing assortment of various types of new lasers at marked-down/discount prices.
The Matchbox series offers excellent performance and reliability in the “World’s Smallest” ultra-compact, all-in-one, integrated laser head. They can operate on a 5V power supply while maintaining low noise operation. The monolithic design of the Matchbox Series laser includes thermally stabilized optics in a hermetically sealed housing, ensuring reliable and maintenance-free operation. This series is available in wavelengths from 405 nm thru 1064nm, with options for collimated beam or fiber-coupled output, and single-mode and multimode versions.
The HL Series offers versatile and high-quality laser diode products in a variety of wavelengths and high-power options,ideal for direct imaging, industrial, and bio/medical applications. These reliable, efficient, and compact diodes come in TO-Can packages, making them perfect for OEM integration. Additionally, they operate with TE mode oscillation and are RoHS compliant, ensuring safe use. Choose the HL Series for quality, reliability, and performance in laser diodes.
The JDL series of high-power laser bars are industry-leading and designed for a variety of optical pumping and DDL applications in materials processing, medicine, and sensing. Our unmounted laser bars offer a wide range of emitter configurations, cavity lengths, and operational modes up to 500 W. Our diode laser stacks can scale power into the multikilowatt range. We focus on delivering the highest-quality laser solutions with a commitment to reducing cost of ownership for our customers.
The JenLas D2 series of 532nm CW disk lasersoffers cutting-edge laser technology with the highest electro-optical efficiency and beam quality, achieved through the suppression of thermal lensing. With advanced waterless cooling and TEC-controlled internal frequency doubling LBO crystals, they provide reliable and consistent performance. The family features a compact and rugged design, with high power capabilities, and our D2 mini laser which fits in the palm of your hand, allowing for easy integration into your system.Nd:YVO4 or Yb:KYW solid state lasers are ideal for industrial micro material processing and medical treatments.
The JOLD–Stacks Series offers a highly modular approach for power scaling well into the kW-range through vertical stacking of individual sub-mounts within multi-laser-bar packages. Our optimized beam quality (BPP) is achieved through our unique approach of reducing the pitch of neighboring stacks without compromising cooling capacity. Our proven hard-solder technology and strictly monitored production processes ensure tried & tested reliability under even the harshest environmental conditions. The series also features microchannel-cooled packages for CW-operation, actively cooled with deionized (DI) water.