An arbitrary-wavelength circularly polarized light generator and method based on a rotating wave plate

Abstract

The application discloses a kind of arbitrary wavelength circularly polarized light generators and methods based on rotating wave plate.Any wavelength circularly polarized light generator based on rotating wave plate includes first wave plate and second wave plate;The first wave plate and the second wave plate are the optical device that can make the additional optical path difference or phase difference between the vibration of the incident light vibration direction perpendicular to each other;The first wave plate and the second wave plate, the phase delay under any working wavelength satisfies, wherein Φ 1 is the phase delay of the first wave plate, Φ 2 is the phase delay of the first wave plate.The application has simple structure, convenient operation, strong applicability and high reliability.

Description

Technical Field

[0001] This invention belongs to the field of optical technology and relates to the generation and control of polarized light, specifically to an arbitrary wavelength circularly polarized light generator and method based on a rotating waveplate. Background Technology

[0002] Generating circularly polarized light is a crucial task in polarization optics, essential for optical detection, remote sensing, and imaging. While generating circularly polarized light of a single wavelength can be achieved by passing linearly polarized light through a quarter-wave plate, generating circularly polarized light of any specified wavelength within a wavelength range is more challenging. The traditional approach is to pass linearly polarized light through a waveplate with variable phase delay. However, using waveplates with variable phase delay has several limitations, such as high manufacturing difficulty, environmental sensitivity, and poor reliability under harsh operating conditions. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides an arbitrary wavelength circularly polarized light generator and method based on a rotating waveplate. This invention has a simple structure, is not dependent on the specific waveplate operating mode, is easy to operate, has strong applicability, and high reliability.

[0004] The technical solution adopted by this invention to solve its technical problem is as follows:

[0005] An arbitrary wavelength circularly polarized light generator based on a rotating waveplate includes a first waveplate and a second waveplate; the first waveplate and the second waveplate are optical devices that can generate an additional optical path difference or phase difference between the vibrations of incident light with mutually perpendicular polarization directions.

[0006] The phase delay of the first and second waveplates at any operating wavelength satisfies -1≤cotφ1cotφ2≤1, where Φ1 is the phase delay of the first waveplate and Φ2 is the phase delay of the first waveplate.

[0007] Both the first and second wave plates can be rotated freely around the optical axis by manual rotation or motor rotation.

[0008] The aforementioned arbitrary wavelength circularly polarized light generator based on a rotating waveplate, denoted as ω1, has the polarization direction of the linearly polarized incident light making an angle with the fast axis of the first waveplate, and ω2, making an angle with the fast axis of the second waveplate. The determination results of ω1 and ω2 required to generate circularly polarized light at the working wavelength are as follows:

[0009] When cos2εsin2εcos2θ(1-cosφ)+cos2εsin2θsinφ>0, rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in right-handed circularly polarized light; rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in right-handed circularly polarized light. The position determined by ω2=ω1+γ indicates that the emitted light is left-handed circularly polarized.

[0010] When cos²εsin²εcos²θ(1-cosφ)+cos²εsin²θsinφ<0, rotating the first and second waveplates to positions determined by ω₁=θ-θ₀ and ω₂=ω₁+γ results in left-handed circularly polarized light; rotating the first and second waveplates to positions determined by ω₁=θ-θ₀ and ω₂=ω₁+γ results in left-handed circularly polarized light. The position determined by ω2=ω1+γ results in right-handed circularly polarized light.

[0011] Where γ is the difference between the angle w2 between the fast axis of the second waveplate and the x-axis and the angle w1 between the fast axis of the first waveplate and the x-axis; Φ is the total phase delay of the first and second waveplates; ε is the total ellipticity of the first and second waveplates; and θ is the total azimuth angle of the first and second waveplates.

[0012] A method for generating circularly polarized light of arbitrary wavelength based on a rotating waveplate, using the aforementioned circularly polarized light generator of arbitrary wavelength;

[0013] Let ω1 be the angle between the polarization direction of the linearly polarized incident light and the fast axis of the first waveplate, and ω2 be the angle between the polarization direction of the linearly polarized incident light and the fast axis of the second waveplate. The method for determining ω1 and ω2 required to generate circularly polarized light at the working wavelength is as follows:

[0014] First, calculate the parameters γ, φ, ε, s1, s2, B'1, B'2, θ0, β, and θ:

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024] θ = β / 4

[0025] When cos2εsin2εcos2θ(1-cosφ)+cos2εsin2θsinφ>0, rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in right-handed circularly polarized light; rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in right-handed circularly polarized light. The position determined by ω2=ω1+γ indicates that the emitted light is left-handed circularly polarized.

[0026] When cos²εsin²εcos²θ(1-cosφ)+cos²εsin²θsinφ<0, rotating the first and second waveplates to positions determined by ω₁=θ-θ₀ and ω₂=ω₁+γ results in left-handed circularly polarized light; rotating the first and second waveplates to positions determined by ω₁=θ-θ₀ and ω₂=ω₁+γ results in left-handed circularly polarized light. The position determined by ω2 = ω1 + γ results in right-handed circularly polarized light.

[0027] The beneficial effects of this invention are:

[0028] When linearly polarized light is incident, this invention can generate circularly polarized light at any specified wavelength within a certain wavelength range. By controlling the rotation angles of the first and second waveplates, the operating wavelength of the device and the rotation direction of the emitted circularly polarized light can be selected. This invention has a simple structure, is easy to operate, has strong applicability, and high reliability. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a structure for an arbitrary wavelength circularly polarized light generator based on a rotating waveplate.

[0030] Figure 2 This is a schematic diagram showing the fast axis orientation of the first and second wave plates.

[0031] In the diagram, 1 is the first wave plate; 2 is the second wave plate; 3 is the first electric rotary table; 4 is the second electric rotary table; and 5 is the electric rotary table controller. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Example

[0034] like Figure 1 As shown, an arbitrary wavelength circularly polarized light generator based on a rotating waveplate includes a first waveplate 1 and a second waveplate 2.

[0035] The first and second waveplates are selected based on the dispersion relation satisfying (where Φ1 is the phase delay of the first waveplate, Φ2 is the phase delay of the first waveplate, λ0 = 670nm, and λ is the wavelength) a 670nm quarter-wave plate.

[0036] The first wave plate 1 is mounted on the first electric rotating platform 3, and the second wave plate 2 is mounted on the second electric rotating platform 4. The first electric rotating platform 3 and the second electric rotating platform 4 are controlled by the electric rotating platform controller 5, which can respectively drive the first wave plate 1 and the second wave plate 2 to rotate around the optical axis to any specified position.

[0037] like Figure 2 As shown, the polarization direction of the linearly polarized incident light is denoted as the x-axis (the optical axis is parallel to the z-axis, and the incident light propagates in the positive z-axis direction). The angle between the fast axis of the first waveplate 1 and the x-axis is ω1, and the angle between the fast axis of the second waveplate 2 and the x-axis is ω2. By changing the angles ω1 and ω2 using the electric rotary stage controller 5, the arbitrary wavelength circularly polarized light generator based on the rotating waveplate can generate circularly polarized light of arbitrary rotation direction for any specified wavelength in the range of 460nm-670nm. The ω1 and ω2 required to generate circularly polarized light at the working wavelength λ (460nm-670nm) are determined by the following method.

[0038] First, calculate the parameters φ1, φ2, γ, φ, ε, s1, s2, B'1, B'2, θ0, β, and θ: γ is the difference between the angle w2 between the fast axis of the second waveplate and the x-axis and the angle w1 between the fast axis of the first waveplate and the x-axis; Φ is the total phase delay of the first and second waveplates; ε is the total ellipticity of the first and second waveplates; S1 and S2 are the total Stokes vector components of the first and second waveplates; B'1 and B'2 are the x and y coordinates of the intersection point projected onto the equatorial plane, respectively; θ0 is the total initial azimuth of the first and second waveplates, β is four times θ, and θ is the total azimuth of the first and second waveplates.

[0039] (where λ0 = 670 nm),

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049] θ = β / 4

[0050] When cos2εsin2εcos2θ(1-cosφ)+cos2εsin2θsinφ>0, rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in right-handed circularly polarized light; rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in right-handed circularly polarized light. The position determined by ω2 = ω1 + γ results in left-handed circularly polarized light.

[0051] When cos²εsin²εcos²θ(1-cosφ)+cos²εsin²θsinφ<0, rotating the first and second waveplates to positions determined by ω₁=θ-θ₀ and ω₂=ω₁+γ results in left-handed circularly polarized light; rotating the first and second waveplates to positions determined by ω₁=θ-θ₀ and ω₂=ω₁+γ results in left-handed circularly polarized light. The position determined by ω2 = ω1 + γ results in right-handed circularly polarized light.

[0052] Table 1 below lists the values ​​of ω1 and ω2 required to generate left-handed (or right-handed) light at certain operating wavelengths.

[0053] Table 1

[0054]

[0055] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A generator for circularly polarized light of arbitrary wavelength based on a rotating waveplate, characterized in that, Including the first wave film and the second wave film; The first and second waveplates are optical devices that can generate additional optical path difference or phase difference between the vibrations of incident light with polarization directions perpendicular to each other. The phase delay of the first waveplate and the second waveplate at any operating wavelength satisfies -1≤cotφ1cotφ2≤1, where Φ1 is the phase delay of the first waveplate and Φ2 is the phase delay of the first waveplate. Let ω1 be the angle between the polarization direction of the linearly polarized incident light and the fast axis of the first waveplate, and ω2 be the angle between the polarization direction of the linearly polarized incident light and the fast axis of the second waveplate. The results of determining ω1 and ω2 required to generate circularly polarized light at the working wavelength are as follows: When cos2εsin2εcos2θ(1-cosφ)+cos2εsin2θsinφ>0, rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in right-handed circularly polarized light; rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in right-handed circularly polarized light. The position determined by ω2=ω1+γ indicates that the emitted light is left-handed circularly polarized. When cos2εsin2εcos2θ(1-cosφ)+cos2εsin2θsinφ<0, rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in left-handed circularly polarized light; rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in left-handed circularly polarized light. The position determined by ω2=ω1+γ results in right-handed circularly polarized light. Where γ is the difference between the angle w2 between the fast axis of the second waveplate and the x-axis and the angle w1 between the fast axis of the first waveplate and the x-axis; Φ is the total phase delay of the first and second waveplates; ε is the total ellipticity of the first and second waveplates; and θ is the total azimuth angle of the first and second waveplates.

2. The arbitrary wavelength circularly polarized light generator based on a rotating waveplate according to claim 1, characterized in that, Both the first and second wave plates can be rotated freely around the optical axis by manual rotation or motor rotation.

3. A method for generating circularly polarized light of arbitrary wavelength based on a rotating waveplate, characterized in that, The arbitrary wavelength circularly polarized light generator described in claim 1 is used; Let ω1 be the angle between the polarization direction of the linearly polarized incident light and the fast axis of the first waveplate, and ω2 be the angle between the polarization direction of the linearly polarized incident light and the fast axis of the second waveplate. The method for determining ω1 and ω2 required to generate circularly polarized light at the working wavelength is as follows: First, calculate the parameters γ, φ, ε, s1, s2, B'1, B'2, θ0, β, and θ: θ = β / 4 When cos2εsin2εcos2θ(1-cosφ)+cos2εsin2θsinφ>0, rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in right-handed circularly polarized light; rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in right-handed circularly polarized light. The position determined by ω2=ω1+γ indicates that the emitted light is left-handed circularly polarized. When cos2εsin2εcos2θ(1-cosφ)+cos2εsin2θsinφ<0, rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in left-handed circularly polarized light; rotating the first and second waveplates to positions determined by ω1=θ-θ0 and ω2=ω1+γ results in left-handed circularly polarized light. The position determined by ω2 = ω1 + γ results in right-handed circularly polarized light.

Images