Non-total internal reflection broadband diffraction prism grating

Abstract

The utility model discloses a non-total internal reflection broadband diffractive prism grating, which comprises a prism, a grating substrate, a grating layer, a metal layer and a glass substrate, the prism is a polyhedron made of transparent materials and plays a role in light guide and dispersion, the grating substrate and the prism are made of the same material, and the grating layer and the metal layer are made of transparent materials. The grating layer is a high-refractive-index optical film layer with a periodic structure, the metal layer is made of gold, the glass substrate is optical glass, the period of the diffraction grating is 750-833 nm, the grating groove is rectangular, and the depth is 0.5-0.55 [mu] m. The non-total internal reflection broadband diffraction prism grating is formed by bonding the glass substrate with the metal layer and the grating. The grating is clamped between the grating substrate and the glass substrate with the metal layer, the effect of protecting the grating is achieved, the grating can be used in various extreme environments, when light enters at the angle smaller than the total internal reflection angle, the metal layer can effectively isolate transmitted energy, most diffraction energy is concentrated on the-1-level diffraction efficiency, the wavelength range is 1510 nm to 1630 nm, and the grating can be used in various extreme environments. And the diffraction efficiency of light in different polarization states is greater than 92%.

Description

Technical Field

[0001] This utility model relates to the field of optical element technology, specifically to a non-total internal reflection broadband diffraction prism grating. Background Technology

[0002] A prism grating, also known as a prism grid, is a combination of a prism and a grating. It combines the dispersive properties of both gratings and prisms, achieving light dispersion and spectral splitting through the diffraction of the grating and the refraction of the prism. The working principle of a prism grating is based on the diffraction and refraction of light. When incident light passes through the grating, the markings on the grating diffract the light, producing a diffraction spectrum. The generation of the diffraction spectrum is based on Hervessel's principle, that is, the incident light beam interacts with the markings on the grating to form a series of alternating bright and dark interference fringes. These fringes correspond to different wavelengths of light, thus achieving light dispersion and diffraction. When light is incident on a grating inside a prism at an angle smaller than the total internal reflection angle of the prism material, some energy will be transmitted out through refraction and diffraction, reducing the diffraction efficiency of the grating. Therefore, when designing a prism grating, it is usually necessary to ensure that light is incident inside the prism at an angle larger than the total internal reflection angle of the prism material. This restricts the freedom of the light path and results in a narrow bandwidth. High diffraction efficiency is usually only achieved within ±25nm of the designed center wavelength. Utility Model Content

[0003] The purpose of this invention is to provide a non-total internal reflection broadband diffraction prism grating to solve the above-mentioned technical problems.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a non-total internal reflection broadband diffraction prism grating, comprising a prism and a grating substrate bonded together with the prism, wherein the grating layer is deposited on the grating substrate and the required periodic structure is fabricated by micro-nano processing, the metal layer is vapor-deposited on a glass substrate, and the metal layer and the grating layer are bonded together by bonding.

[0005] The period of the grating layer is 750-840nm, and the groove of the grating layer is rectangular with a depth of 0.5-0.55μm.

[0006] Preferably, the grating layer material is a high-refractive-index optical film, niobium oxide.

[0007] Preferably, the bonding method between the grating substrate and the prism is optical adhesive bonding or glue-free bonding.

[0008] Preferably, the metal layer is made of gold.

[0009] Preferably, the grating substrate and the glass substrate are made of optical glass.

[0010] Preferably, the refractive index of the prism material is set to 1.863.

[0011] Preferably, the exit surface of the prism is coated with an anti-reflection film.

[0012] Preferably, the antireflective film is made of magnesium fluoride, which is used to reduce light reflection loss at the prism exit surface and improve light transmittance.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0014] Non-total internal reflection broadband diffraction prism gratings are constructed by bonding a glass substrate with a metal layer to the grating, sandwiching the grating between the grating substrate and the glass substrate with the metal layer. This process protects the grating and allows it to be used in various extreme environments. When light is incident at an angle smaller than total internal reflection, the metal layer can effectively block the transmitted energy, concentrating most of the diffraction energy at the -1st order diffraction efficiency. The wavelength range is 1510nm-1630nm, and light of different polarization states can achieve a diffraction efficiency greater than 92%. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Fig. 1 This is a cross-sectional schematic diagram of a non-total internal reflection broadband diffraction prism grating structure according to the present invention;

[0017] Fig. 2 The diffraction efficiency curves of different polarization states of a non-total internal reflection broadband diffraction prism grating embodiment of this utility model are shown.

[0018] Fig. 3 This is a schematic diagram of a non-total internal reflection broadband diffraction grating prism structure according to the present invention.

[0019] The attached diagram lists the components represented by each number as follows:

[0020] 1. Glass substrate; 2. Metal layer; 3. Grating layer; 4. Grating substrate; 5. Prism; 6. Anti-reflection coating. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0022] Please see Figs. 1-3 This utility model provides a technical solution: a non-total internal reflection broadband diffraction prism 5 grating, including a prism 5 and a grating substrate 4 bonded together with the prism 5, a grating layer 3 deposited on the grating substrate 4, and the required periodic structure is fabricated by micro-nano processing, a metal layer 2 is vapor-deposited on a glass substrate 1, and the metal layer 2 and the grating layer 3 are bonded together.

[0023] The period of grating layer 3 is 750-840nm, the groove shape of grating layer 3 is rectangular, and the depth is 0.5-0.55μm.

[0024] Specifically, the grating layer 3 is made of niobium oxide, a high-refractive-index optical film. By setting the grating layer 3 to niobium oxide, the diffraction efficiency of the grating can be effectively improved, while the mechanical strength and thermal stability of the grating can be enhanced.

[0025] Specifically, the bonding method between the grating substrate 4 and the prism 5 is either optical adhesive bonding or glue-free bonding. Through the above settings, the connection between the grating substrate 4 and the prism 5 is made stronger, while avoiding the absorption and scattering of light by the adhesive, thereby improving the diffraction efficiency of the grating and the transmittance of light.

[0026] Specifically, the metal layer 2 is made of gold, which has good electrical conductivity and chemical stability. It can effectively prevent the grating layer 3 from being corroded by the external environment, while improving the reflection efficiency and light transmittance of the grating. The presence of the metal layer 2 can also enhance the stability of the grating structure, making the entire grating structure more robust and durable.

[0027] Specifically, the grating substrate 4 and the glass substrate 1 are made of optical glass. Optical glass has high light transmittance, low absorption and low scattering characteristics, which can effectively reduce the loss of light during transmission and improve the diffraction efficiency and light transmittance of the grating.

[0028] Specifically, the refractive index of the prism 5 material is set to 1.863. By setting the refractive index of the prism 5 material to 1.863, the diffraction angle of the grating in the prism 5 is more accurate, which further improves the diffraction efficiency of the grating and the utilization rate of light.

[0029] Specifically, the exit surface of prism 5 is coated with an antireflection film 6. Furthermore, the antireflection film 6 is made of magnesium fluoride, used to reduce light reflection loss at the exit surface of prism 5 and improve light transmittance. Through the application of the antireflection film 6, light loss at the exit surface of prism 5 is effectively controlled, thereby improving the diffraction efficiency and light utilization of the entire grating system. In addition, the antireflection film 6 can also protect the exit surface of prism 5 from external environmental corrosion, extending the service life of the grating system.

[0030] A specific application embodiment of this example is as follows: A niobium oxide thin film with a thickness in the range of 0.5-0.55um is deposited on the grating substrate 4. A periodic grating with a period in the range of 750nm-840nm and a duty cycle in the range of 0.5-0.7 (duty cycle refers to the proportion of the grating with film layer in one period) is etched by micro-nano processing. The grating groove is rectangular. The grating substrate 4 is photo-adhesive or glued to the prism 5. A gold thin film with a thickness greater than 100nm, namely metal layer 2, is deposited on the grating substrate 4. The metal layer 2 and the grating layer 3 are bonded together by bonding.

[0031] The system includes a prism 5 and a grating substrate 4 bonded to the prism. A grating layer 3 is deposited on the grating substrate 4, and the required periodic structure is fabricated using micro / nano processing. A metal layer 2 is deposited on a glass substrate 1, and the metal layer 2 is bonded to the grating layer 3. The refractive index of the prism 5 material is set to 1.863, resulting in a total internal reflection angle of 32°. With an incident angle of 30° (less than the total internal reflection angle), the RCWA formula algorithm is used... Fig. 2 As shown, its diffraction efficiency can exceed 92%. Its bandwidth is 1510nm-1630nm.

Claims

1. A non-total-internal-reflection broadband diffractive prism grating, characterized by: It comprises a prism (5) and a grating base (4) glued with the prism (5), the grating layer (3) is plated on the grating base (4), the required periodic structure is processed by micro-nano processing, the metal layer (2) is evaporated on the glass base (1), and the metal layer (2) is combined with the grating layer (3) by bonding. The period of the grating layer (3) is 750-840nm, the grating layer (3) is rectangular in groove type, and the depth is 0.5-0.55μm.

2. A non-total-internal-reflection broadband diffractive prism grating according to claim 1, characterized in that: The material of the grating layer (3) is high-refraction optical film layer niobium oxide.

3. A non-total-internal-reflection broadband diffractive prism grating according to claim 1, wherein: The gluing mode of the grating base (4) and the prism (5) is optical glue gluing or glue-free bonding.

4. A non-total-internal-reflection broadband diffractive prism grating according to claim 1, wherein: The material of the metal layer (2) is gold.

5. A non-total-internal-reflection broadband diffractive prism grating according to claim 1, wherein: The material of the glass base (4) and the grating base (3) is optical glass.

6. A non-total-internal-reflection broadband diffractive prism grating according to claim 1, wherein: The refractive index of the material of the prism (5) is set to 1.

863.

7. A non-total-internal-reflection broadband diffractive prism grating according to claim 1, wherein: The exit surface of the prism (5) is plated with an anti-reflection film (6).

8. A non-total-internal-reflection broadband diffractive prism grating according to claim 7, characterized in that: The material of the anti-reflection film (6) is magnesium fluoride, which is used to reduce the reflection loss of light on the exit surface of the prism (5) and improve the transmittance of light.

Images