Beamsplitters and dichroic beamsplitters are optical components used to divide incident light into separate beams or wavelength bands. Although there are also crystalline beamsplitters that utilize the interaction with the microstructure of the crystals to alter light, a more common and cheaper alternative are beamsplitters composed of optical coatings deposited on the surfaces of glass substrates, where the optical coatings in the beamsplitters act as the functional elements to fulfill the goals of splitting light.
According to their shapes and constructions, beamsplitters can be categorized into two major types: beam splitter cubes and plate beam beamsplitters. According to the functions and operation principles, beamsplitters can also be classified into polarizing beamsplitters, non-polarizing beam splitters, and dichroic beamsplitters.
Beamsplitter cubes consist of two right-angle triangular prisms cemented together, or combined together using the optical-contact method. The hypotenuse of one of the prisms is coated to reflect or transmit light according to a certain proportion, and the other four faces are ar-coated to minimize ghost images. Beamsplitter cubes excel plate beamsplitters in the aspect that they are more robust and easier to mount, and that the coatings on the interface are less prone to tarnishing since the coatings are preserved within the beam splitter cube.
Beamsplitter cube coatings can be either polarizing or non-polarizing, the two types of beamsplitter coatings serve completely different purposes and operate based on different principles. Polarizing beam splitter (PBS) cube coatings are manufactured and designed using multiple layers of dielectric materials like SiO2 and TiO2 that create a polarization-dependent splitting effect, where the dielectric thin film stack splits light into two polarization components Ts and Tp, and one component passes through with minimal loss, one component is reflected with high reflectivities. The ratio of the ratio of transmitted p-polarized light to s-polarized light is called extinction ratio. Non-polarizing beamsplitter cube coatings, on the other hand, are often coated with hybrid coatings, which combine both metallic and dielectric materials, where the dielectric layer of the hybrid coating enables high transmission to certain wavelengths and the metallic layer achieves the desired reflectance. The coatings are engineered to split light into a specific splitting ratio (i.e. i.e. the amount of light in the reflected arm versus the amount of light in the transmitted arm) while maintaining the incident light’s original polarization state. However, for narrowband context, non-polarizing beamsplitter cube coatings can also be all-dielectric when optimized effects within a narrow wavelength range are required. For broadband non-polarizing beamsplitter coatings, metallic coatings are an excellent choice with their superior spectral independence.
Beamsplitter plates consist of plates with beamsplitter coatings deposited on the surface where light incident on and AR coatings optimized for the incident angle deposited on the back surface to prevent ghost reflection. Plate beamsplitter are more advantageous than beamsplitter cubes in the aspects that they are lightweight and compact, and more durable to high power laser damage because no adhesive is used. Beamsplitter plates also split light via the beamsplitter coating. Just like beamsplitter cubes, beamsplitter coatings for plate beamsplitter can also be sub-categorized as polarizing or non-polarizing, where the former divides light into a certain extinction ratio depending on polarization, and the latter transmits and reflects light according to the designed splitting ratio while preserving the initial polarization.
Dichroic beamsplitters, also known as dichroic mirrors or dichroic filters, are optical plates that split light according to the spectral composition, transmitting a selected wavelength range and reflecting a certain wavelength range. The dichroic beamsplitter coatings can be regarded as edge filters, either being long-pass or short-pass, where the longpass dichroic coatings transmit wavelengths longer than the cut-on wavelength and reflect the short wavelength, and the shortpass dichroic coating transmits wavelength shorter than the cut-off wavelength and reflects the longer ones. Piled using dielectric materials with meticulously fine-tuned thicknesses, Shalom EO’s dichroic optical coatings exhibit minimum absorption.
At Shalom EO, we specialize in providing custom optical coatings, this page specifies our beamsplitter coating services for a wide range of optical applications. We offer tailor-made solutions, delivering optical coatings that meet your exact specifications. Whether you're looking for polarizing beamsplitter coatings, non-polarizing beamsplitter coatings, or dichroic beamsplitters, our advanced coating technologies ensure high extinction/splitting ratio, sharp spectral cut-off/cut-on, and durabilities. Besides, high power polarizing/non-polarizing beamsplitter coatings and high-power dichroic coatings with optimized laser damage threshold are also available.
Shalom EO focuses on professional designing and state-of-the-art manufacturing of optical coatings. With cutting-edge optical coating technologies like ion-assisted deposition electron beam evaporation, precisely controlled coating process in our ISO-6 clean room, and stringent metrological approaches, we are able to offer you a competitive edge for your optics.
