Broadband Splitter

[Gene Honnette]

Zincdie cast housing and fully soldered back ensure the best electrical performance in a variety of splitter types and outputs. Precisely engineered electrical components and materials guarantee peak performance in every condition, location, and environment.

Mount the splitter in the best configuration regardless of the situation. Mount horizontally, vertically, or simply snap the splitter into the Infinity Premise Enclosure eliminating the need for screws and hardware. True Flex housing is the most versatile housing ever built. Enjoy.

Zinc Alloy Die Cast Housing and Back Cover eliminates galvanic corrosion caused by dissimilar metals. A proprietary plating is also applied to provide additional protection agents. Protect what's inside.

Zinc die cast housing and fully soldered back ensure the best electrical performance in a variety of outputs. Precisely engineered electrical components and materials guarantee peak performance in every condition, location, and environment.

By placing the MoCA splitter at the demarcation point, MoCA frequencies will be unable to escape the home, protecting the integrity of your network.

Designed to the highest technical specifications as the traditional Extreme Broadband Splitter line, the MoCA Splitter is another option for MoCA installations.

Thorlabs' Polarizing Beamsplitting Cubes are offered in six sizes and with five beamsplitting coating ranges. These cubes separate the s- and p-polarization components by reflecting the s component with the dielectric beamsplitter coating, while allowing the p component to pass. These cubes are designed to be used with the transmitted beam, which offers an extinction ratio of TP:TS > 1000:1, except the PBS519 2" 420 - 680 nm cube, which offers an average extinction ratio of > 1000:1 over the wavelength range. The reflected beam will only have an extinction ratio of roughly 20:1 to 100:1, depending on the beamsplitter.

The dielectric beamsplitting coating is applied to the hypotenuse of one of the two prisms that make up the cube. Then, cement is used to bind the two prism halves together (refer to the diagram shown above). The engraved dot on the top of the cube indicates the prism with the beamsplitting coating. Light can be input into any of the polished faces to separate the S and P polarizations. Cubes larger than 5 mm also feature engraved arrows indicating one possible orientation.

Please refer to the BS Cube Mounting tab above for information on mounting options and compatibility. Alternatively, our 1" cubes are available pre-mounted in cage cubes. Custom beamsplitter cubes can be ordered by contacting Technical Support. For high power applications, we offer high power polarizing beamsplitting cubes. We also offer polarizing beamsplitter cubes at laser line wavelengths, which have an extinction ratio of 3000:1 (TP:TS). Polyhedron broadband polarizing beamsplitters with high extinction ratios up to 100 000:1, high damage thresholds, and low-GDD are also available.

The specifications to the right are measured data for Thorlabs' polarizing beamsplitter cubes. Damage threshold specifications are constant for a given wavelength range, regardless of the size of the beamsplitter.

The following is a general overview of how laser induced damage thresholds are measured and how the values may be utilized in determining the appropriateness of an optic for a given application. When choosing optics, it is important to understand the Laser Induced Damage Threshold (LIDT) of the optics being used. The LIDT for an optic greatly depends on the type of laser you are using. Continuous wave (CW) lasers typically cause damage from thermal effects (absorption either in the coating or in the substrate). Pulsed lasers, on the other hand, often strip electrons from the lattice structure of an optic before causing thermal damage. Note that the guideline presented here assumes room temperature operation and optics in new condition (i.e., within scratch-dig spec, surface free of contamination, etc.). Because dust or other particles on the surface of an optic can cause damage at lower thresholds, we recommend keeping surfaces clean and free of debris. For more information on cleaning optics, please see our Optics Cleaning tutorial.

When an optic is damaged by a continuous wave (CW) laser, it is usually due to the melting of the surface as a result of absorbing the laser's energy or damage to the optical coating (antireflection) [1]. Pulsed lasers with pulse lengths longer than 1 s can be treated as CW lasers for LIDT discussions.

When pulse lengths are between 1 ns and 1 s, laser-induced damage can occur either because of absorption or a dielectric breakdown (therefore, a user must check both CW and pulsed LIDT). Absorption is either due to an intrinsic property of the optic or due to surface irregularities; thus LIDT values are only valid for optics meeting or exceeding the surface quality specifications given by a manufacturer. While many optics can handle high power CW lasers, cemented (e.g., achromatic doublets) or highly absorptive (e.g., ND filters) optics tend to have lower CW damage thresholds. These lower thresholds are due to absorption or scattering in the cement or metal coating.

Pulsed lasers with high pulse repetition frequencies (PRF) may behave similarly to CW beams. Unfortunately, this is highly dependent on factors such as absorption and thermal diffusivity, so there is no reliable method for determining when a high PRF laser will damage an optic due to thermal effects. For beams with a high PRF both the average and peak powers must be compared to the equivalent CW power. Additionally, for highly transparent materials, there is little to no drop in the LIDT with increasing PRF.

Thorlabs expresses LIDT for CW lasers as a linear power density measured in W/cm. In this regime, the LIDT given as a linear power density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size, as demonstrated by the graph to the right. Average linear power density can be calculated using the equation below.

The calculation above assumes a uniform beam intensity profile. You must now consider hotspots in the beam or other non-uniform intensity profiles and roughly calculate a maximum power density. For reference, a Gaussian beam typically has a maximum power density that is twice that of the uniform beam (see lower right).

Now compare the maximum power density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately. A good rule of thumb is that the damage threshold has a linear relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 10 W/cm at 1310 nm scales to 5 W/cm at 655 nm):

While this rule of thumb provides a general trend, it is not a quantitative analysis of LIDT vs wavelength. In CW applications, for instance, damage scales more strongly with absorption in the coating and substrate, which does not necessarily scale well with wavelength. While the above procedure provides a good rule of thumb for LIDT values, please contact Tech Support if your wavelength is different from the specified LIDT wavelength. If your power density is less than the adjusted LIDT of the optic, then the optic should work for your application.

Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. The damage analysis will be carried out on a similar optic (customer's optic will not be damaged). Testing may result in additional costs or lead times. Contact Tech Support for more information.

As previously stated, pulsed lasers typically induce a different type of damage to the optic than CW lasers. Pulsed lasers often do not heat the optic enough to damage it; instead, pulsed lasers produce strong electric fields capable of inducing dielectric breakdown in the material. Unfortunately, it can be very difficult to compare the LIDT specification of an optic to your laser. There are multiple regimes in which a pulsed laser can damage an optic and this is based on the laser's pulse length. The highlighted columns in the table below outline the relevant pulse lengths for our specified LIDT values.

Pulses shorter than 10-9 s cannot be compared to our specified LIDT values with much reliability. In this ultra-short-pulse regime various mechanics, such as multiphoton-avalanche ionization, take over as the predominate damage mechanism [2]. In contrast, pulses between 10-7 s and 10-4 s may cause damage to an optic either because of dielectric breakdown or thermal effects. This means that both CW and pulsed damage thresholds must be compared to the laser beam to determine whether the optic is suitable for your application.

The energy density of your beam should be calculated in terms of J/cm2. The graph to the right shows why expressing the LIDT as an energy density provides the best metric for short pulse sources. In this regime, the LIDT given as an energy density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size. This calculation assumes a uniform beam intensity profile. You must now adjust this energy density to account for hotspots or other nonuniform intensity profiles and roughly calculate a maximum energy density. For reference a Gaussian beam typically has a maximum energy density that is twice that of the 1/e2 beam.

Now compare the maximum energy density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately [3]. A good rule of thumb is that the damage threshold has an inverse square root relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 1 J/cm2 at 1064 nm scales to 0.7 J/cm2 at 532 nm):

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