Microchip Lasers are alignment-free, passively q-switched, diode-pumped solid-state (DPSS) lasers, allowing for rugged, compact laser modules that are ideal for low SWaP, portable, handheld applications.
Microchip lasers (sometimes called micro lasers or microlasers) are a specific subset of q-switched DPSS lasers. These lasers utilize a simplified q-switching technology called passive q-switching, which uses a saturable absorber material, such as Cr4+:YAG for pulse generation. Unlike electro or acousto optical q-switching, this passively q-switching relies on the absorption of laser radiation to enable pulsing. When induced with laser radiation the saturable absorber eventually reaches a state of saturation where a pulse is emitted, and the absorber becomes unsaturated. Due to the nature of this passively q-switched technology the pulse amplitude and pulse shape are very repeatable.
Furthermore, the compact and alignment-free nature of the microchip laser design allows them to be made utilizing production techniques which allow for compact, ruggedized packaging at a relatively low cost. As a result, microchip lasers are ideal for integration into range finding, LIDAR, portable LIBS, and other portable or UAV applications, for example. Additionally, through the use of second, third, and fourth harmonic generation they can emit wavelengths from the ultraviolet @ 236.5nm through the infrared @ 1064nm. OEM fiber laser packages and modules are available.
Our Microchip Laser Products
RPMC Lasers provides a selection of microchip laser configurations to match your application requirements. These ultra-compact, passively q-switched, single longitudinal mode (SLM), narrow linewidth, DPSS lasers feature pulse durations from 400 ps to 2 ns, energy levels up to 100 µJ, and repetition rates up to 100 kHz. In addition to the fundamental 1064 nm wavelength and its harmonics (532, 355 and 266 nm), we also deliver units emitting at 946 and 473 nm.
Deeper Dive into Microchip Lasers
The Basics of Microchip Laser Harmonics
Microchip lasers have been around since 1989, when they were first produced at MIT’s Lincoln Labs, but it wasn’t until recently that they became commonplace in the commercial laser market. As such, they are still somewhat misunderstood. In this blog, we will take some time and explain their functionality and why they are so uniquely suited as compact pulsed laser sources at a wide variety of laser wavelengths. Microchip lasers are a specific subset of q-switched DPSS lasers where a passive q-switch is monolithically bonded to the laser crystal. These passive q-switches, which are typically semiconductor saturable absorber mirrors (SESAM), act as both the q-switch and the output coupler, allowing for tiny optical cavities. The compact and alignment-free nature of microchip lasers enables them to be constructed utilizing telecom production techniques, allowing for compact, ruggedized packaging at a relatively low cost. As a result, microchip lasers are ideal for integration into range finding, scribing, and marking systems.
Surprisingly this resonator geometry allows for the generation of short pulse width (sub-nanosecond) lasers with high peak powers often greater than tens of kilowatts. The high peak powers make these lasers ideal for an external and intracavity harmonic generation. External cavity second harmonic generation was first achieved in 1996 by bonding a thin nonlinear KTP crystal, coated to be highly reflective at 1064 nm and anti-reflective at 532nms. This crystal is then bonded to the front of a microchip laser’s Nd:YVO4 crystal (the active medium). Within two years, third and fourth harmonic microchip lasers were also demonstrated using an external crystal to produce 355nm and 266nm lasers. In order to fully understand why these lasers are ideal for harmonic generation, it is important to review the fundamental physics underlying this nonlinear process.
As we previously described in our white paper on two-photon microscopy, the simplest way of understanding this nonlinear optical effect is by looking at the relationship between the polarization density (P), the materials susceptibility tensor (c) (related to the index of refraction of the marital), and the electric field of the incident laser (E). Sum frequency generation, also referred to as second harmonic generation, is what is known as a second-order nonlinear effect and obeys the following relationship,
From Equation 1, it is clear that the effect is highly dependent on the magnitude of the electric field. Since the electric field density is dependent upon both the laser’s pulse duration and pulse energy, the shorter the pulse width and the larger the peak power, the more efficient it will be at harmonic generation. To further improve the nonlinear conversion efficiency of microchip lasers, researchers at the University of St. Andrews used an intracavity geometry where the intensity is far higher, and the beam waist can be controlled to produce more difficult wavelengths such as red and yellow.
Today through second, third, and fourth harmonic generation, microchip lasers are now commercially available with emission wavelengths from the ultraviolet through the infrared. The simplicity of these passively q-switched lasers makes them relatively inexpensive compared to most short pulse lasers. It allows for an ultra-compact design powered by a standard 15V power supply.
Microchip Lasers: Fully Integrated Modules for LIDAR & 3D Scanning
The SB1 Microchip laser module series from Bright Microlaser, provides all the features you need for a successful, low-cost, compact, and reliable OEM LIDAR solution. These diode-pumped solid-state (DPSS) microchip lasers are available in several standard configurations, in wavelengths of interest for LIDAR applications (532nm & 1064nm), with output power up to 400 mW, pulse energies up to 80µJ, and pulse widths from a few nanoseconds down to 350ps. These microchip lasers use a saturable absorber passive q-switch, with factory-set repetition rate from single shot to 100kHz. Utilizing a passive q-switch means you don’t need an extra driver, allowing for a cheaper and more compact design. Read more about passive vs. active q-switching. The single longitudinal mode (SLM) SB1 series exhibits single-frequency operation, producing narrow linewidths, with high-quality beam output (M2 <1.3), and a pulse to pulse instability of <3%.
The Advantages and Disadvantages of Passive vs Active Q-Switching
Both of these q-switching techniques produce short pulses and high peak powers, but they each have their pros and cons. For example, active q-switching allows the user far more control over when the pulse will be emitted and therefore how long population inversion will be allowed to build up. But, on the other hand many common active q-switches such as Pockels cells (which utilize the electro-optic effect) often require the driver to swing several kilovolts each time the switch is triggered. By contrast saturable absorbers require no drivers at all, meaning that not only are they compact, but they are also far less expensive. As a result, when you are deciding between an active versus passive q-switched laser there are four key things that you must keep in mind.
With over 25 years experience providing microchip 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 info@rpmclasers.comto talk to a knowledgeable Product Manager.
Alternatively, use the filters on this page to assist in narrowing down the selection of microchip 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.
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