The Waveplates, also known as phase delay plates, can create an additional optical path difference (or phase difference) between two linearly polarized lights that are perpendicular to each other, thereby changing the polarization state of light. It can be used to adjust the polarization state of a light beam, usually made of quartz birefringent chips with precise thickness, whose optical axis is parallel to the surface of the chip.

A half wave plate (half wave plate) can rotate linearly polarized light by any angle, which is twice the angle between the opposite polarization of the incident light and the optical axis. For example, the optical axis of a wave plate is 22.5 °. The polarization state of the emitted light is converted clockwise by 45 °; The optical axis of the waveplate is 45 degrees. The polarization state of the emitted light is converted clockwise by 90 degrees. When circularly polarized light is incident, the emitted light is circularly polarized with opposite rotation direction.

A 1/4 waveplate can delay linearly polarized light by 1/4 wavelength and convert it into circularly polarized light. On the contrary, they can also convert circularly polarized light into linearly polarized light.

The commonly used wavelengths are 266nm, 355nm, 532nm, 632.8nm, 780nm, 850nm, 1064nm, 1550nm

Application areas: In the fields of laser, optical communication, instruments, etc., it is used for polarization state conversion requirements of beam combiners, as well as isolators and circulators.