22 May 2024
Optical Fiber, Mid-IR

Unlocking Mid-IR: The Power of Chalcogenide Optical Fibers

Mid-infrared light, generally defined as the 3-50 μm range, has enormous potential due to the fingerprint-like signatures of many molecules at these wavelengths. The oscillation frequencies of this light match the frequencies of vibrations of molecular bonds, enabling a wide range of high-sensitivity applications across many industries.

For example:

  • Infrared Imaging and Sensors: Chalcogenide fibers have excellent transmission properties in the mid-infrared (IR) range, typically from 2 to 12 micrometers (μm), making them ideal for IR imaging, spectroscopy, and sensing applications.
  • Military and Security: The mid-IR range is crucial for defense applications.  The best known one is, of course, night vision technology.  But optical fibers are also needed to transmit mid-IR wavelengths to create secure communication links and sensors that can detect threats or monitor hazardous environments.
  • Medical Applications: In medical diagnostics, chalcogenide fibers facilitate the transmission of IR light, which can be used for the diagnosis of diseases through the analysis of tissue or blood samples based on their IR absorption characteristics in spectroscopy.
  • Nonlinear Optics: Chalcogenide fibers exhibit high nonlinear optical coefficients, allowing for efficient nonlinear optical processes like supercontinuum generation and parametric amplification.

A special fiber with special characteristics

Chalcogenide glass transmits light with low losses at longer wavelengths than silica glass and can be used to make fibers (see Figure 1) and optical components for mid-infrared applications. Chalcogenide glass is chemically stable and insensitive to moisture, an advantage over other mid-infrared materials.

Coractive began manufacturing chalcogenide glasses and fibers in 2005. Our special high purity glass, developed in-house by optimizing methods for precursor purification and glass processing, ensures excellent control of the optical fiber quality to meet the requirements of mid-infrared applications.

Figure 1. Chalcogenide glass

Different formulations of chalcogenide glasses transmit in different mid-infrared ranges. For example, our arsenic selenide fibers transmit from approximately 2-6 μm, while our arsenic sulfide fibers transmit from approximately 2-9 μm. (See Figure 2). Our chalcogenide fibers are available in different form factors to transmit single mode or multimode laser signals at different wavelengths, depending on the needs of specific applications. One of our fibers (IRT-SE-12/170 SEG) was specifically optimized for supercontinuum generation. Others are optimized for beam delivery for quantum cascade lasers and supercontinuum lasers, allowing the user to bring mid-infrared light to the sample of interest.


Figure 2. Typical transmission losses of chalcogenide glass optical fibers. AsS: arsenic sulfide; AsSE: arsenic selenide.

The reasons for choosing chalcogenide optical fibers over other materials often includes their unique transmission window in the mid-IR range, highly nonlinear optical properties, and the ability to operate effectively in environments or applications where silica fibers are not suitable. These properties enable significant advancements in technology and applications across a wide range of fields. Contact us, and our team of experts will be happy to help you choose or even develop the right chalcogenide fiber for your mid-infrared application!