FODL-MDX

Modular rack system for fiber optic delay lines. Delay range up to 660 ps, resolution < 0.33 fs. Remote control options via ethernet/USB. Ideal fit for coherent beam combining and many other research and industrial applications.

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Key features

State-of-the-art optical performance

Our delay line offers an optical delay range of 330 ps or 660 ps with an unprecedented resolution of < 0.33 fs across the whole range. Low insertion loss is maintained even at 2000 nm wavelength.

Industrial grade interface for remote control (ethernet + USB)

Apart from an intuitive web interface, a control via USB or ethernet interfaces allows automation on industrial level. Up to 8 delay line units can be driven by the same controller.

Fiber and connector selection

FC/APC and FC/PC standard is used for fiber connections. Both polarization maintaining (PM) and single mode (SM) fibers are available.

Plug-and-play solution compatible with 19” rack system

Both the delay line units and the controller are made as insert modules for a 19” subrack. The subrack has integrated PCB-based connections between the delay lines and the controller. If ordered together, the system comes preconfigured and ready to use.

Status LED

Each delay line is equipped with a signal LED providing live visual status inspection (power / home / error).

Variants

Any combination of the parameters can be chosen.

Number of delay line units (subrack height)

1-3 (1x3U)
4-8 (2x3U)

Operating wavelength

1550 nm
2000 nm

Optical delay range

330 ps
660 ps

Fiber type

polarization maintaining (PM)
single mode (SM)

Fiber connectors

FC/APC
FC/PC

Specifications

Specifications	Delay lines
Operating wavelength [nm]	1550		2000
Optical delay range [ps]	330	660	330	660
Typical insertion loss [dB]	1.4	1.7	2.2	2.3
Insertion loss uniformity [dB]	0.25	0.35	0.25	0.35
Optical delay resolution [fs]	< 0.33
Polarization extinction ratio [dB]	> 20
Fiber type	PM-1550 / SM-1550 SM-1550		PM-1950 / SM-1950 SM-1950
Fiber connectors	FC/APC, FC/PC
Dimensions [mm]	76.4 x 106 x 286.5
Operating temperature [°C]	10 - 40

	Controller
Power requirements	12/24V, 5A
Control	web GUI / ethernet / USB
Dimensions [mm]	177.9 x 106 x 286.5

	Subrack (MDX)
Number of delay lines	1-3		4-8
Dimensions [mm]	482.6 x 265.9 x 298.5		482.6 x 132.5 x 298.5
Weight of fully loaded MDX [kg]	11.3 / 12.2		24.1 / 26.5

Product description

We introduce a new product made by OptiXs – FODL-MDX, a modular rack system for fiber optic delay lines. It is a plug-and-play solution for applications where multiple optical delay lines are required in a single setup, such as coherent beam combining. The default configuration comes with 8 delay line units + 1 controller all supplied as insert modules in a 19” subrack with 2 x 3U height. Yet, thanks to the modularity of MDX, basically any number of delay line units can be configured. PCB-based connectors are integrated in the subrack case - the connection between the delay line units and the controller is realized simply by pushing the inserts into their positions. If ordered all together, everything is set up by us and ready to use.

The optical design and performance of the delay lines is derived from their stand-alone version. Depending on the selected type, we offer an optical delay range of 330 ps or 660 ps with an unprecedented resolution of < 0.33 fs across the whole range. Low insertion loss (< 1.4 dB) and high insertion loss uniformity (0.25 dB) are maintained. You can choose between operating wavelengths of 1550 nm and 2000 nm. In either case polarization-maintaining (PM) fibers with FC/APC connectors placed on the front face of the case are used by default. Single mode (SM) fibers and FC/PC connectors are also available.

A single controller enables a computer based remote operation of up to 8 delay lines. For basic use we include an intuitive customized web interface, while ethernet and USB connections provide options for more advanced communication and automatization. Each delay line is equipped with a signal LED showing the status of the unit (power / home / error).

* Delay line version operating at 1550 nm. For more details, see specifications table.

Applications

Coherent beam combining

Coherent beam combining is a power scaling technique, where multiple laser beams are combined into a single output with preserved beam quality and correspondingly enhanced power. The key to success in CBC is ensuring that all combined beams share a stable mutual coherence: their phases must be precisely synchronized and their wavefronts properly aligned.
Achieving and maintaining this delicate phase alignment typically involves fine-tuning the path length of each beam. Fiber optic delay lines solve this challenge by allowing operators to adjust the optical path length with high accuracy and stability.
CBC allows generation of high power output from fiber lasers that can be used in application areas such as laser directed-energy systems, or material cutting and processing.

Research applications

In cutting-edge research labs, optical delay lines serve as valuable tools for fine-tuning light signals with extreme precision—often down to sub-femtosecond levels. By enabling minute adjustments of path length, they help researchers perform highly sensitive interferometric measurements, synchronize ultrafast laser pulses, and explore new frontiers in spectroscopy. The result is enhanced experimental control, improved data accuracy, and the ability to unlock groundbreaking discoveries in fields spanning from fundamental physics to high-speed communication technologies.

Consultation

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Articles

11. 04. 2025 Coherent beam combining

High-power fiber lasers have become central to both industrial and defense-oriented applications, thanks to their compact designs, relative efficiency, and low running costs.

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Are you interested in product? Send us your requirements via the enquiry form or contact an expert consultant directly. We will be happy to answer your questions and propose a solution according to your needs.

Expert advisor

Ing. Ondřej Pavelka

+420 732 282 621

pavelka@optixs.cz