PBS CUBES COMPARED: STANDARD, HIGH POWER AND BROADBAND
While visually all PBS cubes might appear the same, they have major differences. Polarizing beamsplitter cube production from polishing and coating to combining prisms results in different wavelength range to extinction ratio, LIDT.
Single band PBS vs Broadband PBS cubes
While most of the physical characteristics are the same for single and broadband options, including the method of combining the prisms, the few key differences occur. First – the material. Broadband PBS cube material must have specific refraction index to ensure performance in broad regions. Second – extinction ratio is few times higher in high energy PBS cubes as all spectral characteristics are optimized for single wavelength.
High power vs low-medium power
Signs that PBS cube is suitable for high power applications
We recommend checking how the prisms are combined – optical adhesives cannot withstand high powers. Alien Photonics high energy PBS cubes are optically contacted and show excellent spectral performance in both single band and multi-band and broadband versions. Next - extinction ratio – while high ratio suggests premium coatings, it is not necessarily high power. Coating must be suitable for high energy (some coating materials cannot be used for high energy).
Signs that PBS cube is for low energy systems
Firstly – optical adhesive in interface. Secondly – low extinction ratio while itself is not direct LIDT factor, it signals that cube is not precision, likely economical PBS cube option.
Temperature stability and shelf-life
Optically contacted cubes are way less sensitive to temperature changes. The optical adhesive in standard PBS cubes limits not only the performance at elevated temperatures, but also how long it can be stored without special conditions. This “on the shelf lifetime” is much longer with optically contacted (high power option) cubes.
All Alien Photonics PBS cube types compared – summary table
The bellow comparison of Alien Photonics PBS cubes. For more information about each parameter – check our guide on PBS parameters.
| Feature | Low-medium energy PBS | Low-medium energy broadband PBS | High energy PBS | High energy broadband PBS |
|---|---|---|---|---|
| Product link | PBS: low-medium | Broadband PBS: low-medium | PBS: high energy | Broadband PBS: high Power |
| Material example | N-BK7 | N-SF1 | UVFS | N-SF1 |
| Surface quality | 40-20 S-D | 60-40 to 40-20 S-D | 40-20 or 20-10 S-D | 40-20 or 20-10 S-D |
| Flatness & TWFD (Typical) | λ/4~λ/6 | λ/4~λ/6 | λ/4~λ/8 | λ/4~λ/8 |
| Combining method | Optical adhesive | Optical adhesive | Optical contact | Optical contact |
| Beam Deviation (Typical) | <3 arcmin | <3 arcmin | <3 arcmin | <3 arcmin |
| Reflection (Rs) | >99.5% | >99% | >99.5% | >99% |
| Transmission (Tp) | >97% | >92% (avg.) | >97% (>96% for UV) | >92%(avg.) |
| Extinction Ratio (Tp/Ts) | >1:500 | >1:250 | >1:1000 | >1:250 |
| LIDT | ~0.3 J/cm² | ~0.3 J/cm² | >15 J/cm² | >3 J/cm² |
When to choose which PBS cube
Broadband PBS cube intended applications would include tunable laser systems, spectroscopy – analysis of broadband light, polarization sensitive experiments. Standard low-medium energy cubes – great choice for visual applications, LED and low-power DPSS laser modules. High power cubes – perform best in high energy laser systems, pulse picking setups, and other optical systems requiring robust PBS cubes, like quantum or micromachining
Contact Alien Photonics or check other polarizers !