Thorlabs' LCDR633 Liquid Crystal Polarization Rotator accepts arbitrarily linearly polarized light and can rotate the output polarization through >360°. A feedback mechanism detects and stabilizes the azimuth of the output light.
Figure 1.1 A KLC101 K-Cube controller is required to control the LCDR633 polarization rotator.
- Smooth and Continuous Rotation of Arbitrary Linear Input Polarization
- Standalone or Remote Operation with KLC101 Controller
- Stabilized Output Azimuth with Closed-Loop Feedback
- Compact Design with Extinction Ratio >820:1
- 633 nm Operating Wavelength
Features
- Rotate Arbitrary Linear Input Polarization Continuously Through >360°
- Feedback Design Stabilizes Output Azimuth
- 633 nm Operating Wavelength with Input Power Up to 300 mW
- Mounting Features on Input and Output Ports
- Requires KLC101 LC Controller (Sold Separately)
Thorlabs' LCDR633 Liquid Crystal Deterministic Rotator (LCDR), controlled by the KLC101 Liquid Crystal Controller, can continuously rotate the polarization state of an arbitrary linearly polarized input beam through over 360° with no mechanical movement involved. An internal closed-loop feedback mechanism analyzes the output beam and adjusts the driving voltage of the liquid crystal retarder to stabilize the output azimuth (as illustrated in Figure 1.2).
The LC polarization rotator consists of a liquid crystal variable retarder and two quartz zero-order quarter-wave plates; the LC retarder and wave plates have their fast axes oriented at 45° with respect to each other, as shown in Figure 1.2. With arbitrarily linearly polarized light incident on the polarization rotator, azimuth rotation of the output polarization can be achieved by adjusting the liquid crystal retardation. The linearly polarized input beam can have any arbitrary polarization angle.
The rotator includes 1.5 m long BNC and Hirose cables for use with the KLC101 LC controller, which is required and sold separately. The KLC101 controller that is used must be manufactured in 2025 or later (serial numbers larger than 39486044) and use firmware version 1.14.64 or higher. Earlier versions of this controller or those with older firmware will not function properly with the LCDR633 polarization rotator.
Operating Principle
The LCDR incorporates two modules: an azimuth rotation module that implements the rotation of linearly polarized input light, and the azimuth detection module that detects the azimuth orientation of the output light. The communication between these two modules is what makes this closed-loop feedback system deterministic.
The azimuth rotation module consists of a liquid crystal variable retarder and two quartz zero-order quarter-wave plates. The LC retarder and wave plates have their fast axes oriented at 45° with respect to each other. Such a configuration allows smooth and continuous rotation of arbitrarily linearly polarized input light.
The azimuth detection module contains photodiodes which collect the intensity of four linear polarization states of the sampled light: -45°, 0°, 45°, and 90°. These intensities are then used to compute the actual output azimuth.
Utilizing the azimuth rotation module combined with the azimuth detection module and a feedback control circuit (integrated with the KLC101 LC controller), the LCDR can eliminate the azimuth fluctuation in linearly polarized light, achieving output azimuth stabilization within 0.05° (RMS), which is ideal for applications requiring precise and stable linear polarizations, such as polarization photo alignment, direct laser writing (with linear polarization modulation), and linear polarization encoding in quantum optics, e.g., quantum key distribution (QKD), quantum computing, and quantum sensing.
Figure 1.2 Schematic Showing the Operating Principle of the Azimuth Rotation and Detection Modules
| Table 1.1 Key Specs | ||
|---|---|---|
| Operating Wavelength | 633 nm | |
| Input Optical Power | 0.1 to 300 mW | |
| Clear Aperture | Ø5.0 mm | |
| Angle of Incidence | 0° | |
| Output Azimuth Rotation Resolutionb | 0.1° | |
| Output Azimuth Accuracyb | ±2° | |
| Output Azimuth Stabilityb | <0.05° (RMS) | |
| Extinction Ratioc | >820:1 | |
| Linear Polarization Rotation Range | >360° | |