Single Longitudinal Mode Laser

Single Longitudinal Mode lasers produce light at a single frequency or wavelength, making them useful for various applications where a stable wavelength and very narrow linewidth are essential.

While all lasers are inherently monochromatic, unless care is taken to stabilize the spectral output, the center frequency can vary over time, causing the time-averaged spectral linewidth to broaden. The linewidth of a laser refers to the width of the laser’s spectral line when viewed in a spectrograph. The laser linewidth is typically characterized by its full-width at half-maximum (FWHM), or its root mean square (RMS) linewidth. For example, a laser with a FWHM linewidth of 1 MHz is considered to have a narrow linewidth.

SLM (Single Longitudinal Mode) laser diodes and modules are designed to emit light at a single frequency or wavelength. This is achieved by ensuring that only one mode within the laser cavity reaches the gain threshold necessary for lasing. Not all SLM lasers are inherently wavelength stabilized. While many SLM lasers are designed to maintain a stable wavelength, especially for applications requiring high precision, this is not a universal feature. Wavelength stabilization typically involves additional components or techniques, such as temperature control, feedback mechanisms, or external cavity designs, to ensure the laser maintains a consistent wavelength over time and varying conditions. So, while SLM lasers often have narrow linewidths and stable wavelengths, not all of them are explicitly wavelength stabilized. It depends on the specific design and application requirements of the laser.

Our Single Longitudinal Mode Products

We offer a selection of stabilization technologies including distributed feedback (DFB) and volume Bragg grating (VBG) diode lasers as well as a wide variety of temperature and current stabilized DPSS solutions. These lasers are available in OEM and turn-key packages which can be either single-mode or multimode beam profiles and free-space or fiber-coupled outputs. Narrow linewidth lasers are widely used in spectroscopy, gas sensing, holography, and interferometry.

Part Number	Wavelength (nm)	Description	Type
LGK-XXX	543, 594, 633	He-Ne Laser Module, Single mode, 543-633nm, up to 20mW	HeNe Lasers, Narrow Linewidth, Long Coherence Length, Single Longitudinal Mode (SLM), Collimated Beam, Fiber-Coupled
LGR-XXX	543, 594, 633	He-Ne Laser Replacement Tube, Single mode, 543-633nm, up to 20mW	HeNe Lasers, Narrow Linewidth, Long Coherence Length, Single Longitudinal Mode (SLM), Collimated Beam, Fiber-Coupled
LXC-Combiner	Multiple Wavelength Options	Laser Combiner, Single mode, up to 6 Wavelengths, 375-1064nm, up to 500mW	LD Module, CW DPSS Lasers, Narrow Linewidth, Long Coherence Length, Single Longitudinal Mode (SLM), Collimated Beam, Fiber-Coupled, Customizable
LXX-IR-SLM	785, 830, 1064	Laser Module, Stabilized, Infrared, 785-1064nm, up to 300mW	LD Module, CW DPSS Lasers, Narrow Linewidth, Long Coherence Length, Single Longitudinal Mode (SLM), Collimated Beam, Fiber-Coupled, Customizable
LXX-VIS-SLM	532, 553, 561, 633	Laser Module, Stabilized, Visible, 532-633nm, up to 300mW	LD Module, CW DPSS Lasers, Narrow Linewidth, Long Coherence Length, Single Longitudinal Mode (SLM), Collimated Beam, Fiber-Coupled, Customizable
MB-IR-SLM	785, 830, 1030, 1064	Laser Module, Stabilized, Infrared, 783-1064nm, up to 500mW	LD Module, CW DPSS Lasers, Narrow Linewidth, Long Coherence Length, Single Longitudinal Mode (SLM), Collimated Beam, Fiber-Coupled
MB-VIS-SLM	405, 488, 520, 633	Laser Module, Stabilized, Visible, 405-633nm, up to 170mW	LD Module, CW DPSS Lasers, Narrow Linewidth, Long Coherence Length, Single Longitudinal Mode (SLM), Collimated Beam, Fiber-Coupled
REPXXXX-DM	759-764, 1260-1310, 1500-1560, 1560-1600, 1635-1670, 1720-1770, 2300-2333	Laser Diode, Stabilized, 1278-2327nm, up to 20mW	LD Module, Single Emitter, DFB, Narrow Linewidth, Single Longitudinal Mode (SLM), Fiber-Coupled
RPK-IR-STAB	785, 808, 878, 976, 1064	Laser Diode, Wavelength Stabilized, Fiber-coupled, Infrared, 760-1400nm, up to 430W	Multi-Emitter, VBG, Narrow Linewidth, Single Longitudinal Mode (SLM), Fiber-Coupled
RVBG	633, 680, 785, 808, 860, 976, 1030, 1064	Laser Diode, Stabilized, 633-1064nm, up to 600mW	LD Module, Single Emitter, VBG, Narrow Linewidth, Single Longitudinal Mode (SLM), Fiber-Coupled, Made in the USA
RWLD-DFB	1064, 1270, 1460, 1485, 1660	Laser Diode, Wavelength Stabilized, SWIR, 1270-1600nm, up to 30mW	Single Emitter, DFB, Narrow Linewidth, Single Longitudinal Mode (SLM)
RWLP-DFB	1270, 1310, 1410, 1460	Laser Diode, Wavelength Stabilized, Fiber-coupled, SWIR, 1270-1460nm, up to 100mW	Single Emitter, DFB, Narrow Linewidth, Single Longitudinal Mode (SLM), Fiber-Coupled
SB1-IR	946, 1064	DPSS Laser, ns/ps pulsed, 946-1064 nm, up to 80µJ, up to 100kHz	Pulsed DPSS Lasers, Microchip Lasers, Airborne Laser, Single Longitudinal Mode (SLM), Low SWaP, Ruggedized
SB1-UV	236.5, 266, 355	DPSS Laser, ns pulsed, 236.5-355nm, up to 2µJ, up to 10kHz	Pulsed DPSS Lasers, Microchip Lasers, Airborne Laser, Single Longitudinal Mode (SLM), Low SWaP, Ruggedized
SB1-VIS	473, 532	DPSS Laser, ns/ps pulsed, 473-532nm, up to 40µJ, up to 100kHz	Pulsed DPSS Lasers, Microchip Lasers, Airborne Laser, Single Longitudinal Mode (SLM), Low SWaP, Ruggedized
SMX-DFB	1310, 1550	Laser Diode, Wavelength Stabilized, 1310nm or 1550nm, up to 100mW	Single Emitter, DFB, Narrow Linewidth, Single Longitudinal Mode (SLM), Fiber-Coupled, Made in the USA

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Single Longitudinal Mode Laser Benefits

There are several benefits to using a SLM laser:

Precise wavelength control: They produce light with a particular and stable wavelength, which makes them useful for applications where precise wavelength control is essential.
High spectral purity: Because the spectral width of the laser output is very small, the light produced is highly pure and free from contaminating frequencies (single frequency lasers).
Improved measurement accuracy: In applications such as spectroscopy and metrology, the use of a narrow linewidth laser can improve measurement accuracy by eliminating errors that broad-spectrum light sources may introduce.
Increased signal-to-noise ratio: In telecommunications and other applications where the laser is used to transmit a signal, they can provide a higher signal-to-noise ratio compared to a laser with a broader linewidth. This can improve the overall performance of the system.
Enhanced stability: Known for their long-term stability, which makes them useful in applications where stability is essential, such as in atomic clocks.

How Can We Help?

With over 25 years of laser experience 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.

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