An active Q-switch laser is a type of laser that uses an externally controlled variable attenuator, known as a Q-switch, to modulate the intracavity losses, allowing energy to build up in the laser medium and then suddenly be released, providing pulsed laser output.
Active q-switches could be a mechanical shutter device, an optical chopper wheel, or spinning mirror / prism inside the optical cavity. However, typically, they are in the form of a modulator, such as an acousto-optic, magneto-optic, or electro-optic device (e.g., a Pockels cell or Kerr cell). Active q-switches rely on a controllable on/off ability and rapidly adjust the lasers cavity loss. A perfect example of this is an acousto-optic modulator, which, when activated creates a grating which deflects many spontaneously emitted photons out of the laser cavity. However, once the modulator is turned off, it allows the spontaneous photons to pass through and initiate stimulated emission.
Should I choose an actively q-switched or passively q-switched laser?
There are pros and cons to both types (active & passive). There are some main points to consider when determining which type best suits your application needs:
Cost – passively q-switched lasers are less expensive and complex than actively q-switched lasers
Size – passively q-switched lasers can be significantly more compact than actively q-switched lasers
Triggering – actively q-switched lasers allow precise triggering control over pulses and does not suffer from the increased pulse to pulse jitter, as opposed to passively q-switched lasers
Pulse Energy – actively q-switched lasers typically provide higher pulse energies than passively q-switched lasers
Our Active Q-Switch Products
RPMC offers a selection of Actively Q-Switched lasers at various levels of integration from OEM to turn-key, benchtop, laboratory and research laser systems. We group our active q-switch laser products into a few different categories, including Pulsed DPSS Lasers, Pulsed Fiber Lasers, Ultrafast Lasers, Tunable Lasers, and MIL-Spec. Lasers.
We provide many popular wavelength options, as well as non-standard wavelengths within the ultraviolet (UV), Violet, Blue, Green, Yellow, Red, near-infrared (NIR), short-wave infrared (SWIR), and mid-wave infrared (MWIR) spectral regions. Average output powers for these q-switched laser options range from a few 10s of mW (milliwatts) up to 150 W (watts), and pulse energy options ranging from a few nJ (nanojoules) up to around 200 mJ (millijoules).
On this page, you will find active q-switch lasers with pulse width options available from 125 ns down to 100 fs. A wide range of repetition rate options are available from single shot up to 80 MHz.
RPMC Lasers is your preferred Active Q-Switch Laser Supplier, partnering with industry-leading and emerging manufacturers. We have been in business for over 25 years, providing researchers and OEM integrators with the best laser solution for their application. We have fielded 1000s of units for many different applications from micromachining to LIDAR and Bathymetry to medical applications such as tattoo removal and ablation-based surgical procedures.
Deeper Dive into Actively Q-Switched Lasers
Peak Power and Average Power in ns and Sub-ns Lasers:
Necessarily, the smoother leading and trailing edges of a Gaussian pulse slightly reduce (by a factor of 0.94) the peak power for given pulse energy or average power. The point is that the situation might be further complicated when lasers emitting few-nanosecond-long or sub-nanosecond (e.g., picosecond) pulses come into the picture. Usually, a Gaussian pulse shape is an excellent approximation for the real pulse profile of Q-switched DPSS lasers, even though it is accurate only for lasers operating in single longitudinal mode (SLM). Most commercially available Q-switched lasers rely on multiple longitudinal modes, oscillating at the same time with constant interference. This effect is visible by acquiring optical pulses with sufficiently fast photodiodes and digital oscilloscopes, showing an amplitude modulation superimposed to the Gaussian pulse shape.
The period and depth of the modulation depend on the number of longitudinal modes oscillating together. For tens-of-nanoseconds-long pulses, resonators support so many modes that the modulation is averaged out and hardly visible. Still, for sub-nanosecond operation, only a few modes are left, giving rise to deep modulation on the pulse envelope and strong deviation from the ideal Gaussian shape. A full-width half-maximum pulse duration definition becomes questionable, and a more refined statistical definition should be employed, giving rise to a correction factor for the peak power higher than 1 (potentially a factor of 1.5 could be a reasonable guess).
The Advantages and Disadvantages of Passive vs Active Q-Switching:
While there are a wide variety of q-switch technologies, notably including acousto-optic and electro-optic modulators, the technique as a whole can be broken down into two primary categories of q-switches, passive and active. Active q-switches rely on the ability of “flip a switch” and rapidly adjust the lasers cavity loss. A perfect example of this is an acousto-optic modulator, which, when activated creates a grating which deflects many spontaneously emitted photons out of the laser cavity, but once the modulator is turned off it allows the spontaneous photons to pass through and initiate stimulated emission. Passive q-switches, on the other hand, take advantage of a process known as saturable absorption. Saturable absorption derives from the fact that there is a limit to the amount of light that a material can physically absorb at a given wavelength before the energy level become saturated and the material becomes temporarily transparent. As a result, if a saturable absorbing material is placed inside of the laser cavity, it will absorb all of the spontaneously emitted photons until it reaches saturation where it will then allow the photons to pass through and initiate stimulated emission.
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.
Why is a Low Jitter Feature Important in Actively Q-Switched DPSS Lasers?
In actively Q-switched lasers, the user controls the pulsed laser output, so that no laser pulse emission occurs without providing a proper input signal, aka “the trigger”. Due to the trigger signal propagation through the interface electronics, the Q-switch driver chain, and the laser resonator build-up time, a time delay (Td) is present between the externally supplied trigger signal and the actual laser pulse emitted by the laser source. The Td can show fluctuations if any electronics or optics involved in the pulse generation process have a functional variance in time.
The parameter Td is very relevant in the timing management of some applications. You must consider both the time delay (Td) and a time jitter (Tj), which is a statistical variation of the time delay depending mostly on:
electrical noise in the trigger-chain
pulse-to-pulse fluctuation of trigger-chain electrical parameters
laser pulse build-up time-mechanism and associated fluctuations.
fluctuation of rising (-falling) edge temporal profile of the trigger signal
Because of the jitter phenomena, the actual value of the time delay is statistically altered. Therefore, the laser pulse emission event happens (in the vast majority of cases) inside a normal time distribution, defined by an average time delay Td and a standard deviation value Tj (i.e 68.2 out of 100 pulses develop in the time interval Td ±Tj).
High-Energy Q-Switched Lasers for Harmonic Generation – Part 1
Solid-state lasers offer many advantages over other laser sources. One of their most unique benefits is the ability to produce extremely high pulse energy. Solid-state lasers can achieve this through q-switching, which is a process where the resonator losses are periodically increased, therefore interrupting the lasing process. Unlike other laser pulsing methodologies, q-switching is unique in that the pump source remains active while no lasing is occurring. Constant pumping forces the laser crystal to store the energy from the pump, similar to a capacitor. And just as with a capacitor in an electrical circuit, once you flip the switch and lasing can once again occur, the crystal will “discharge” all of the stored energy as fast as physically possible, resulting in an extremely high-energy laser pulse.
High-Energy Q-Switched Lasers for Harmonic Generation – Part 2
In our last blog post (Part 1), we highlighted the benefits of high-energy q-switched lasers for harmonic generation. In that article, we reviewed how q-switched lasers work and why the resultant short duration, high-energy pulses are required for higher-order harmonics. So, we won’t rehash that here. Instead, we will highlight another set of lasers offered here at RPMC, which are ideal for higher-order harmonic generation, allowing it to produce wavelengths from the infrared to the ultraviolet; the Sol, Wedge, and Onda from Bright Solutions. All three of these laser sources are robust and compact, making them ideal for integration into OEM systems. In this blog, we will highlight several of the features which make each unit uniquely suited for harmonic conversion.
Laser Requirements for Time Gated Active Night Vision Imaging Systems
That being said, in many active imaging systems, one is not merely interested in producing a two-dimensional image, but instead creating a three-dimensional “point cloud” of the environment. To produce such an image, the system must have a way of recording the round-trip time-of-flight (TOF) of the light. As a result, the camera and the illumination source must be pulsed, and the IR camera must be time-gated. This is remarkably similar to TOF lidar or TOF radar  with the exception that, instead of measuring the return signal with a single photodetector, the receiver is instead an infrared camera. While in theory this process could be done with an SLD, when you gain switch a diode source, the peak power of the laser is the same as in continuous operation, and as a result the pulse energy is typically rather low. By contrast, if a q-switched laser is used, short pulses can be generated with considerable peak powers. Since only a fraction of a percentage of the transmitted light from the IR illuminator will ever make it back into the imaging system, it is imperative that the pulse contains as much energy as possible to maximize the overall effacing.
While liquid water does have significantly lower absorption at these shorter wavelengths, that is not the only factor that will determine the lasers ability to penetrate deep below the surface of the water; scattering is also a significant factor. Even if you measure crystal clear water, there will always be a certain amount of scattering associated with the Rayleigh effect. As a result, it is essential to use a laser with significant pulse energy, for enough photons to survive the round-trip flight back out of the body of water without scattering or being absorbed. Additionally, the laser must have as short a pulse width as possible since the depth resolution is directly proportional to the pulse width of the laser. A detailed explanation of this relationship is beyond the scope of this blog post, but it should be reasonably straightforward to understand that the lidar system cannot resolve TOF less than the width of the laser pulse itself.
With all of these factors taken into consideration, it isn’t a surprise that very few lasers possess the pulse width, pulse energy, form factor, and active q-switching required for bathymetric lidar.
Raman Spectroscopy: Why are Picosecond Pulses Superior to Femtosecond?
Raman-based spectroscopy, on the other hand, is an entirely different nonlinear technique, relying on the frequency shift experienced by laser radiation incident on a molecule, related to its rotational and vibrational modes. Not being related to electronic transitions, the Raman shift is relative concerning the irradiating wavelength, and therefore, unless pursuing coherent excitation, laser source tunability is not required. Raman-based spectroscopy, being a nonlinear process, usually requires ultrashort pulse generation (e.g., practical TPA set-ups usually require < 300 fs pulse duration). On the other hand, since the Raman gain is generally higher than TPA cross-sections, cheaper and simpler picosecond lasers could be efficiently employed in incoherent Raman spectroscopy. Furthermore, in Raman spectroscopy, the spectral resolution is related to the laser source bandwidth. Therefore, the narrower bandwidths of picosecond lasers represent a remarkable advantage over their femtosecond counterparts.
With 1000s of fielded units, and over 25 years of experience, providing researchers with the best laser solution for their application, our expert team is ready to help! 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 actively q-switched 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.
The FL-P series of pulsed fiber lasers is manufactured to Telcordia standards and is suitable for various applications with average powers up to 5W at 1um and 1.5um, peak powers up to 25kW, and pulse widths in the range of 400ps to 50ns. Available in both OEM and Turnkey formats, this series offers a variety of standard and custom configurations. Available options include pulse monitoring, int/ext triggering, TTL or LVDS input signals, extended operating temperature range, and a robust design.
The Aero Series is a high-energy, nanosecond pulsed DPSS laser, available at 266, 355, 532, and 1064nm, with up to 10W output power & 200mJ pulse energy at 1064. This series provides unparalleled precision and accuracy in even the most challenging environments. All models come enclosed in an extremely compact and ruggedized single unit with a conductively cooled heatsink and a water-cooled option. It comes with available options for beam expanding and collimating optics. This laser series is ideal for LIBS, spectroscopy, and Atmospheric LIDAR applications.
The AIRTRAC-MIL series is a ruggedized, high-shock, ultra-compact, actively q-switched, low-SWaP, DPSS laser, available with up to 70 mJ @ 532 & 1064 nm. Fully compliant NATO STANAG 3733 configurations for laser designation are available in a complete system weighing less than 1 lb. The athermal design of the AIRTRAC ensures high laser pulse energy, and stable performance over the full temperature range with low beam divergence.
The Wedge series of DPSS lasers is designed for OEM applications such as micromachining, LIDAR, LIBS, and more. Based on proprietary fast Q-switching technology, this series is compact, sealed, and monolithic, making them insensitive to vibrations & harsh environments. High peak powers, relatively low energy and low heat generation allow efficient ablation and non-linear interaction. Available from 266-3106nm, up to 4 mJ pulse energy @ 1064, the compact and lightweight package benefits LIDAR and aerospace applications, while short pulses provide exact time-of-flight measurements.
The CEUV series is a commercial line of compact and efficient DPSS laser sources, capable of operating over a wide range of pulsing conditions (duty-cycle and PRF), in a low SWaP package, with average power up to ≈5W @ 266nm, 10W @ 355nm or 532nm, 20W @ 1064nm. This series of DPSS lasers provides a combination of compact, efficient, and high-power performance in a rugged design suitable for harsh environments and airborne applications. The design has been tested in brassboard hardware and a prototype is being developed.
The JenLas Fiber ns series is a versatile line of fiber lasers designed for OEM integrators, researchers, and applications specialists working with material processing applications. Available in 20, 30, 55, and 100W power configurations, this air-cooled laser series boasts reliable, industry-tested fiber laser technology and an adjustable pulse length. With pulse duration settings ranging from 50 to 200 nanoseconds and peak pulse powers of up to 8kW, this series offers improved performance and extended control capabilities, allowing for pulse repetition rates and pulse lengths to be changed by choosing different modes. The JenLas Fiber ns series is available with a complete set of customizable accessories, including laser controllers, beam expanders, and air or water cooling.
The Onda series is a DPSS nanosecond OEM laser platform designed for high-end applications requiring excellent beam quality and high peak power in materials such as metals, glass, plastics, and various delicate and hard materials. This compact and easy to use laser series is available in wavelengths of 266, 355, 532, and 1064nm, with an extended operating temperature range and superior performance to cost ratio. The Onda series’ internal optical layout and accurate temperature management enable high output energies without compromising the lifetime of the THG and FHG stages.
The Q-TUNE-G series is a highly advanced air-cooled, tunable wavelength laser with seamless OPO integration. It offers hands-free, automated tuning from 680 to 2100 nm, delivering up to 12 mJ pulse energy in the near-IR range. With a <10 cm-¹ linewidth and up to 100 Hz pulse repetition rate, it’s ideal for photoacoustic imaging, non-linear spectroscopy, and more. The user-friendly web interface and microprocessor control ensure ease of use, while the water-free, air-cooled pump laser design optimizes performance. The Q-TUNE-G series sets a new standard in precision and efficiency for researchers across disciplines.
The Q-TUNE-IR series is the perfect high peak power, coherent, DPSS light source for researchers working with infrared spectroscopy applications. This series uses an Optical Parametric Oscillator (OPO) to produce tunable wavelength in the 1380 – 4500 nm range with a linewidth less than 10 cm-1, achieving > 6.5mJ of pulse energy @ 3500nm for the F-10 configuration (> 2mJ @ 3500nm for C-10) with a 10Hz repetition rate. The Q-TUNE-IR requires little maintenance, with all laser electronics integrated into the housing, including an air-cooling system, eliminating the need for chillers or large power supplies, all while providing a guaranteed pump diode lifetime greater than 2 giga-shots.
The Q-TUNE series is a highly efficient, tunable wavelength laser designed for researchers working with temporally resolved spectroscopy, metrology, photo-acoustic imaging, and remote sensing applications. This laser uses an optical parametric oscillator (OPO) to produce a tunable wavelength range of 410-2300 nm with a linewidth narrower than 6 cm-1, which can be extended to 210-410 nm with an optional second harmonic generator. With a pulse duration shorter than 5ns and an upper repetition rate of 100Hz, the Q-TUNE series provides a perfect coherent light source for precise scientific measurements.
The Q-SHIFT series of Q-switched DPSS lasers is designed for researchers and application specialists working in micromachining, dermatology, LIDAR, time-resolved laser spectroscopy, and LIBS applications. With its built-in nonlinear wavelength conversion stage, this series allows the production of unconventional fundamental DPSS wavelengths, including 1163, 1177, 1300, 1317, 1551 and 1571 nm options, making it an ideal choice for those seeking wavelengths that are not accessible with conventional solid-state laser sources. With the optional harmonics generator, it is possible to generate up to the 4th harmonic for each fundamental wavelength, providing even more versatility.
The Q-SPARK series is an air-cooled, diode-pumped, Q-switched laser designed for researchers and application specialists working with ablation, LIDAR, remote sensing, and LIBS applications. The laser produces sub-nanosecond or nanosecond pulses with peak power up to 20 MW and pulse energies up to 10 mJ, making it ideal for a wide range of applications. With a short <1.5 ns pulse, compact air-cooled package, and innovative water-free laser crystal end-pumping technology, the Q-SPARK series delivers high-quality, low divergence, Gaussian-like laser beams.
The Q1 series is a compact, energy-efficient, diode pumped, air-cooled, Q-switched laser available with up to 35 mJ at 1064, 40 mJ at 1053nm, and rep rates up to 50Hz. The high peak powers and low divergence of the Q1 series enable efficient harmonic conversion through the 5th harmonic (213 or 211nm). The innovative design results in a user-friendly, turnkey system that requires little maintenance, and the laser’s variable pulse repetition rate and built-in sync pulse generator provide flexibility for triggering user equipment.
The Q2 series is a diode-pumped, air-cooled, Q-switched laser emitting at 1064 or 1053nm, designed for a wide range of applications that require high peak power pulses. The water-free end-pumping technology produces high peak powers and low divergence, enabling efficient harmonics conversion through the 5th harmonic (213 or 211nm). This versatile platform can be configured in many ways, including up to 80mJ pulse energy at 10 Hz pulse repetition rate or up to 20mJ at 100 Hz. In the short cavity configuration, pulse duration can be reduced by 50% compared to the standard configuration.
The Q2HE series is a high–energy, q-switched, diode-pumped solid-state (DPSS) laser series, available in either 1053nm or 1064nm fundamental wavelengths, with optional 2nd, 3rd, 4th, or 5th harmonic generation. This air-cooled series of lasers is designed for a wide range of applications that require high peak power pulses. Due to a short laser cavity, excellent thermal properties of the crystal, and an innovative water-free crystal cooling technology, the Q2HE series can deliver up to 120mJ of pulse energy and/or up to 4W average output power. This advanced laser design results in a compact, user-friendly turnkey system that requires little maintenance.
The SOL series is the most compact, air-cooled, Q-switched DPSS nanosecond laser available in the power range from 4W to 40W @ 1064nm. With its excellent beam quality, high peak power, wavelength options (10W and 650µJ at 532nm / 4W @ 355nm), and wide range of add-ons, this series is ideal for the most demanding industrial and scientific applications. With a rugged, compact, lightweight, and easy-to-use single-unit design, the SOL laser is easy to integrate into any system, providing superior operational flexibility and performance/cost ratio.
The VaryDisk Series is a versatile family of thin-disk laser systems that provide high pulse energies at high average powers and are suitable for lab or industrial use. These thin-disk regenerative amplifiers offer a range of output specifications and customization options, depending on the configuration and your specific application needs. The base configurations provide options for pulse widths in the fs, ps, and ns range, up to 1000 W average power, 150 mJ pulse energy, 1 kHz to 125 kHz rep. rate, and 1030 nm, 515 nm (SHG), and 343 nm (THG) wavelength options.
The Vento series is a compact and ruggedized sub-nanosecond DPSS laser series designed for scientific and industrial applications such as precision LIDAR and materials processing. With pulse durations down to 500 ps and repetition rates up to 200 kHz, this laser series produces a high average power of up to 25 W @ 532 nm and up to 40 W @ 1064 nm. The Vento series has many options, from beam expanding and collimating optics to a low jitter option to extended operating temperature range, up to IP68 package, remote control cbox & software, and much more.