WOP | Depolarization Compensator

Our depolarization compensator utilizes a spatially variable wave plate (SVWP) tailored to your specific conditions. Crafted with an understanding of the depolarization’s origin and the characteristics of your amplified laser beam, it outshines traditional solutions. Forget about cumbersome setups like intracavity quarter-wave plates or Faraday rotators. With our technology, you get flexibility and precision like never before. The point-by-point inscribed nano-gratings offer versatility, allowing for easy adjustments to meet your unique requirements. Elevate your optics with a solution designed for efficiency and effectiveness!

ADVANTAGES VS. ALTERNATIVES :

• No absorption
• Very low scattering
• Custom and continuous point by point patterns
• Maximum power extraction possibility without additional beam quality degradation
• Flexibility to compensate different amounts of depolarization by stacking more than one element
• Saves space, is easy to handle
• Significantly lower price

WOP solution – depolarization compensator :

High-power lasers often experience thermal effects in their gain medium, resulting in predictable temperature gradients. These gradients create mechanical stresses that induce birefringence, leading to optical anisotropy and significant power losses, especially in systems with polarization-sensitive components like Brewster plates and Faraday rotators.

In collaboration with Ekspla Ltd., Workshop of Photonics (WOP) has developed an innovative solution to address depolarization loss—an optical element that compensates for polarization distortion in the gain medium, as outlined in Ekspla's patent EP3712664.

We investigated this technology using a subpicosecond laser system that included the FemtoLux 30 fiber CPA-based seed laser and a double-pass end-pumped Yb:YAG crystal power amplifier. The key advancement in this system was the integration of a specially designed spatially variable wave plate (SVWP), enabling nearly maximum power extraction from the amplifier without compromising beam quality. To our knowledge, this is the first application of this method.

Depolarization compensator. Left: Two-dimensional distribution map of the orientation of fast and slow axes. Right: Retardance profile.

Our proposed depolarization compensation method – a depolarization compensator – is more beneficial compared to other methods, such as intracavity quarter-wave plate, intracavity Faraday rotator, classical depolarization compensation layout with two identically pumped and relay-imaged gain media, and different crystal cut directions

The reasons are :

• the substrate of spatially variable wave plate (SVWP) is fused silica, providing low bulk absorption of laser radiation and featuring a significantly lower nonlinear refractive index, as compared to a Faraday rotator, thus minimizing thermal effects and nonlinear interaction in high-intensity lasers;
• the SVWP element is compact (6 mm in thickness, usually 25.4 mm in diameter), whereas Faraday rotator material is usually at least 20 mm in length;
• there is the possibility to compensate for depolarization in the highly pumped gain medium, which is not the case using a simple approach with a quarter-wave plate;
• it is not overly sensitive to alignment and specific configuration;
• it is very practical, as induced/compensated depolarization level can be tuned by either changing the incident laser beam size or stacking a few SVWPs in the same optical layout.

Brochures & Datasheets :

   Depolarization compensator brochure (pdf / English)

   Depolarization compensator Article (pdf / English)