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JP-7855574-B2 - Method and system for high-bandwidth immersion grids

JP7855574B2JP 7855574 B2JP7855574 B2JP 7855574B2JP-7855574-B2

Inventors

  • マルシアンテ，ジョン アール．
  • ライドネル，ジョーダン ピー．

Assignees

  • ラム フォトニクス インダストリアル エルエルシー

Dates

Publication Date
20260508
Application Date
20210809
Priority Date
20200807

Claims (20)

  1. It is an immersion grid, A dielectric substrate having an incident light surface and a second surface facing the incident light surface, wherein the dielectric substrate is characterized by the refractive index of the substrate, At least one dielectric layer bonded to the second surface of the dielectric substrate, wherein the at least one dielectric layer is characterized by a layer refractive index greater than the refractive index of the substrate and a predetermined thickness D , and the at least one dielectric layer is A first portion of the at least one dielectric layer having a first thickness d 1 , Including a second portion of the at least one dielectric layer having a second thickness d2 , D = d1 + d2 , A periodic structure is formed within the second portion of the at least one dielectric layer and An immersion grid comprising, wherein the immersion grid is characterized by having a Littrow dispersion of 2.0 radians/μm or less and a diffraction efficiency greater than 99% over a wavelength range of 1041 nm to 1066 nm .
  2. The immersion grid according to claim 1, further comprising an ambient environment, wherein the periodic structure is immersed within the ambient environment.
  3. The immersion grid according to claim 2, wherein no material exists between the periodic structure formed within the at least one dielectric layer and the surrounding environment.
  4. The immersion grid according to claim 1, wherein a light beam is incident on the periodic structure from at least one dielectric layer.
  5. The immersion grid according to claim 1, wherein at least one dielectric layer does not contain metal.
  6. The immersion grid according to claim 1, wherein the immersion grid supports only the order of reflection.
  7. The immersion grid according to claim 1, wherein the periodic structure includes a period measured in one dimension.
  8. The immersion grating according to claim 7, wherein the periodic structure comprises a one-dimensional diffraction grating.
  9. The immersion grid according to claim 8, wherein the immersion grid is configured to generate only diffraction orders m=0 and m=-1.
  10. The immersion grid according to claim 1, wherein the dielectric substrate contains fused silica.
  11. The immersion grid according to claim 1, wherein the at least one dielectric layer is characterized by a thickness of 0.55 μm to 0.7 μm.
  12. The immersion grid according to claim 1, wherein the refractive index of the layer is in the range of 1.9 to 2.2 over a wavelength range of 1030 nm to 1080 nm.
  13. The immersion grid according to claim 1, wherein the at least one dielectric layer comprises at least one of tantalum pentoxide or hafnium oxide.
  14. The immersion grid according to claim 1, wherein the thickness of at least one dielectric layer is 0.45 μm to 0.85 μm.
  15. The immersion grid according to claim 1, wherein the periodic structure is characterized by an etching depth of 0.25 μm to 0.35 μm.
  16. The immersion grid according to claim 1, wherein the periodic structure is characterized by a duty cycle of 0.20 to 0.35.
  17. It is an immersion grid prism, A prism having an incident light surface, an optical surface, and a third surface, wherein the prism is characterized by its refractive index, At least one dielectric layer coupled to the optical surface, wherein the at least one dielectric layer is characterized by a layer refractive index greater than the prism refractive index and a predetermined thickness D , and the at least one dielectric layer is A first portion of the at least one dielectric layer having a first thickness d 1 , Including a second portion of the at least one dielectric layer having a second thickness d2 , D = d1 + d2 , A periodic structure is formed within the second portion of the at least one dielectric layer and An immersion grating prism comprising the above, characterized in that the Littrow dispersion is 2.0 radians/μm or less and the diffraction efficiency is greater than 99% over a wavelength range of 1041 nm to 1066 nm .
  18. The immersion grating prism according to claim 17, wherein the periodic structure is configured to generate diffraction orders passing through the incident light plane.
  19. The immersion grating prism according to claim 18, wherein the diffraction order is m = -1.
  20. The immersion grating prism according to claim 17, wherein the at least one dielectric layer comprises at least one of tantalum pentoxide or hafnium oxide.

Description

Cross-reference of related applications [0001] This application claims priority to U.S. Provisional Application No. 63/062,773, filed on 7 August 2020, the contents of which are incorporated herein by reference in their entirety for all purposes. [0002] A diffraction grating is a periodic structure that typically exists at the interface between two materials, one of which is often air. When a single beam is incident on the grating, it generates multiple (called order) diffracted beams. The angular radiation of the order is as follows: Formula 1 The lattice equations are given by (Equation 1) shown, where θi is the angle of incidence, ni is the refractive index of the incident medium, θ0 is the output angle of a given order m, n0 is the refractive index of the output medium through which the light is diffracted (which may be the same as the incident medium), λ is the wavelength of light, and Λ is the lattice period. Generally speaking, a lattice can produce both transmission orders (orders diffracted from the periodic structure on the opposite side of the incident light) and reflection orders (orders diffracted from the periodic structure on the same side as the incident light). The parameter relationships shown in Equation 1 determine which orders are possible, but physical details of the lattice profile (size and shape of the unit cells of the periodic structure) are needed to calculate how much of the incident power is diffracted to each order. [0003] In relation to Equation 1, it should be noted that the angle of incidence and the angle of diffraction order are related to each other with respect to a given wavelength and lattice periodicity. The diffraction order can exist either inside or outside the medium, corresponding to the reflection order and transmission order, respectively. Accordingly, the diffraction orders inside and outside the medium are coupled by nsin(θ). In embodiments where the transmission order is suppressed, the reflection order is governed by the total internal reflection (TIR) condition. [0004]Figure 1A is a simplified diagram showing a periodic grid existing between air and glass. Light incident from within the glass 810 generates reflection and transmission orders governed by Snell's law (Equation 1). The angles in air are larger with respect to the surface normal than the angles within the glass. Also, since sin(θ 0 ) is greater than 1, the transmission angle cannot be generated by Equation (1), so it should be noted that the order m = -3 exists only within the glass. This is an indication of total internal reflection. In the case of a higher dispersion grid, all angles within the glass can be subjected to total internal reflection, as depicted in Figure 1B. In this way, the transmission order is thought to be suppressed via total internal reflection (TIR). [0005] Conventional diffraction gratings require a surface on which a periodic structure is fabricated. A common method for fabricating a grating is to select a substrate, such as a glass plate, and fabricate a periodic structure on it by etching, deposition, replication, or other methods known to those skilled in the art. When a metal is used as a coating to provide high-efficiency diffraction from the grating, light is incident from the air, diffracted reflectively from the metal grating structure, and does not interact with the glass substrate. This is one of the most common configurations of diffraction gratings used, for example, in spectrometers. However, in photolithography, for example, it is often useful to fabricate a transmission grating where light incident on the grating is diffracted to a transmission order. In a transmission grating, light must pass through the substrate either before or after being diffracted by the transmission grating. This is a simplified diagram showing the periodic grid that exists between air and glass.This is a simplified diagram showing total internal reflection when a grating is present.This is a simplified cross-sectional view of an immersion grid according to one embodiment of the present invention.This is a plot of spectral diffraction efficiency for TE-polarized and TM-polarized light for an immersion grating having a first dispersion.This is a plot of spectral diffraction efficiency for TE-polarized and TM-polarized light for an immersion grating with a second dispersion.This is a plot of spectral diffraction efficiency for TE-polarized and TM-polarized light for an immersion grating having a third dispersion.This plot shows the spectral diffraction efficiency for an immersion grating using a substrate with a first refractive index.This plot shows the spectral diffraction efficiency for an immersion grating using a substrate with a second refractive index.This is a simplified cross-sectional view showing an immersion grid according to one embodiment of the present invention.Figure 4 is a plot showing the spectral diffraction efficiency for the immersion grid shown.This plot sho