The direction of light propagation is linear, and optical fibers have emerged to address the flexibility in guiding incident light.
Optical fibers are optical conduits made using the principle of total internal reflection, allowing for illumination at complex angles.
In typical photocatalysis experiments, the light source needs to be directly aligned with the reactor's light window. However, in some specific photocatalysis experiments constrained by reactor shape and laboratory space, it may be inconvenient to place the light source close to the reactor. In such cases, the light emitted by the light source needs to be redirected into the reactor using optical fibers. Additionally, in some in situ photocatalysis tests, due to the shape of the sample cell and the size of its light window, light redirection is also required, as in the case of in situ photocatalytic infrared diffuse reflection cells.
Optical fibers come in many types, and their functionality and performance vary depending on the fiber material.
In the field of photocatalysis and related research, the most commonly used optical fibers are quartz optical fibers and liquid-core optical fibers.
Quartz optical fibers are made from highly pure quartz glass and possess the following characteristics:
(1) High transmittance: Quartz optical fibers are optically transparent over a wide wavelength range, especially in the infrared region.
(2) High mechanical strength: They can withstand stretching and bending.
(3) High damage threshold: They are less susceptible to phenomena like laser-induced breakdown.
Liquid-core optical fibers use inorganic salt solutions or organic liquids as the core material, sealed by hard transparent materials at both ends as light windows to facilitate full reflection of light within the conduit for forward transmission.
Liquid-core optical fibers have the following characteristics:
(1) Excellent light spot homogenization with no stray speckles.
(2) A large numerical aperture for transmitting more light energy, ensuring high light conduction efficiency.
(3) Strong selectivity for the core material: Different liquids can be chosen to impart specific functionalities.
(4) Excellent ultraviolet band light transmission capacity, suitable for high-power light sources of up to several hundred watts.
Comparison between quartz optical fibers and liquid-core optical fibers
As seen in Figure 1, after attaching quartz optical fibers to a xenon lamp light source, quartz optical fibers exhibit high transmittance in the ultraviolet, visible, and infrared regions between 320 nm and 1050 nm, with minimal variation in spectral composition. However, liquid-core optical fibers exhibit specific absorption between 650 nm and 1050 nm, resulting in some attenuation of the output light intensity in this wavelength range.
Figure 1. Spectral comparison before and after attaching (a) quartz optical fibers and (b) liquid-core optical fibers to a xenon lamp light source
Selection recommendations:
If full-band transmission (320 nm to 1050 nm) or infrared light transmission is required, it is recommended to use quartz optical fibers. If uniformity of light spot is required, and only ultraviolet and visible light transmission is needed, it is recommended to use liquid-core optical fibers.
Compatibility guide:
Quartz optical fibers can be paired with PLS-SXE 300 Xenon Lamp Light Source, PLS-SXE 300UV Xenon Lamp Light Source, PLS-SXE 300D Xenon Lamp Light Source, PLS-SXE 300DUV Xenon Lamp Light Source, Microsolar 300 Xenon Lamp Light Source;
Liquid-core optical fibers can be paired with PLS-SXE 300 Xenon Lamp Light Source, PLS-SXE 300UV Xenon Lamp Light Source, PLS-SXE 300D Xenon Lamp Light Source, PLS-SXE 300DUV Xenon Lamp Light Source, Microsolar 300 Xenon Lamp Light Source, PLS-FX300HU High Uniformity Integrated Xenon Lamp Light Source, CHF-XM500 Mercury Lamp Light Source.
