An improved arrayed waveguide grating spectrometer chip

Abstract

The present invention discloses an improved arrayed waveguide grating spectrometer chip. The chip comprises a substrate, an input waveguide, a free propagation block waveguide, and a waveguide array arranged on the substrate. The waveguide array is primarily composed of a plurality of output waveguides arranged in an array at intervals. The input waveguide, free propagation block waveguide, and output waveguide are sequentially arranged along the propagation direction of light. The input and output ends of the input waveguide are respectively coupled to a light source and the input end of the free propagation block waveguide. The output end of the free propagation block waveguide is respectively coupled to the input ends of a plurality of output waveguides. The output light from the output end of each output waveguide is irradiated onto a detector plane. The tilt angle of the output light beams of each output waveguide in the present invention increases the degree of overlap between the diffraction fields of each output waveguide at the detector plane, enabling the present invention to achieve both output light beam focusing and dispersion functions while also enhancing the intensity, resolution, and contrast of the spectrum.

Description

Technical Field

[0001] The invention belongs to the fields of integrated optics, spectrum analysis and imaging spectrometers, and particularly relates to an improved arrayed waveguide grating spectrometer chip. Background Art

[0002] Since Newton discovered the dispersion phenomenon of a prism, spectrometer technology has developed rapidly. Traditional spectrometers require multiple precision optical components, such as slits, collimators, dispersers, and focusers. This results in complex structures, large size, and difficult alignment. With the development of integrated optics, on-chip spectrometer chips have emerged, addressing the issues of bulk and alignment. To date, researchers have conducted in-depth research on a range of on-chip spectrometers based on integrated optics, including arrayed waveguide gratings, etched diffraction gratings, and Fourier spectrometers. Arrayed waveguide gratings have garnered widespread attention due to their advantages in high spectral resolution and low insertion loss.

[0003] Arrayed waveguide gratings were first widely used in the field of optical communications to achieve wavelength multiplexing and demultiplexing, greatly improving communication efficiency. Arrayed waveguide gratings are also used in astronomy. Because the output channels of arrayed waveguide gratings used in the field of communications have a fixed wavelength interval, continuous spectrum analysis cannot be achieved. Therefore, it is necessary to remove the second free beam propagation area of ​​the arrayed waveguide grating and the waveguide of the subsequent output channel, and directly guide the light in the waveguide array to free space, and then converge it to the optical camera through a convex lens. Although this structure adopts on-chip integration, the use of lenses makes its volume still very large and still requires precise alignment. The existing technology has proposed integrating the focusing function of the lens into the arrayed waveguide grating. The specific approach is to superimpose a length on the basis of the array waveguide length design to meet the wavelength separation. The superimposed waveguide length between each channel just meets the phase condition of the convex lens focusing, thereby achieving the dispersion and focusing functions.

[0004] The structure proposed in the prior art successfully reduces the device size and improves system stability. However, because the output waveguides are parallel to each other, the diffraction field centers of each arrayed waveguide do not overlap. This misalignment of the diffraction field centers leads to a decrease in coherence, reduced spectral intensity, and reduced resolution. This is especially true when the focal length is short or the number of arrayed waveguides is large. This misalignment of the diffraction field centers can lead to increased spectral background light and reduced resolution. In astronomical observations, a short focal length and a large number of arrayed waveguides are required to reduce transmission losses and improve the dispersion capability of the grating. Summary of the Invention

[0005] In view of the deficiencies in the background technology, the present invention proposes an improved arrayed waveguide grating spectrometer chip.

[0006] The technical solutions of the present invention are as follows:

[0007] The invention comprises a substrate, an input waveguide, a free propagation block waveguide and a waveguide array arranged on the substrate. The waveguide array is mainly composed of a plurality of output waveguides arranged in an array at intervals. The input waveguide, the free propagation block waveguide and the output waveguide are arranged in sequence along the propagation direction of light. The input end and the output end of the input waveguide are respectively coupled to the light source and the input end of the free propagation block waveguide. The output end of the free propagation block waveguide is respectively coupled to the input ends of a plurality of output waveguides. The output light of the output end of each output waveguide is irradiated on the detector plane.

[0008] The angles of the output ends of the output waveguides are different from each other.

[0009] The substrate is made of glass, silicon nitride, lithium niobate, gallium arsenide, indium phosphide or silicon.

[0010] The output end of the free propagation block waveguide is a circular arc end face.

[0011] The output waveguide is a curved waveguide or a broken line waveguide.

[0012] A tangent direction of the output end of the free propagation block waveguide is not parallel to an output end of each output waveguide.

[0013] The lengths of the plurality of output waveguides increase in sequence.

[0014] The lengths of the plurality of output waveguides are set according to the following formula:

[0015] l i =P i -P1+(i-1)ΔL+l1

[0016]

[0017] Among them, l i is the length of the i-th output waveguide, l1 is the length of the first output waveguide, i is the index, P i -P1 is the optical path difference that the i-th output waveguide needs to meet relative to the first output waveguide to achieve the convex lens focusing function, ΔL is the length difference that needs to be met between adjacent output waveguides to achieve the dispersion function, m is the spectral order of the improved arrayed waveguide grating spectrometer chip, λ c is the central wavelength of the improved arrayed waveguide grating spectrometer chip, P i is the focal length f minus the distance from the light emitted by the i-th output waveguide to the detector plane to form the interference surface, P1 is the focal length f minus the distance from the light emitted by the first output waveguide to the detector plane to form the interference surface, n eff is the effective refractive index of the core of the output waveguide, f is the focal length, D iis the distance from the output end of the i-th output waveguide to the center output waveguide.

[0018] The central output waveguide is the middlemost output waveguide among all the output waveguides 4 .

[0019] The angle of the output end of the output waveguide is set according to the following formula:

[0020]

[0021] Among them, γ i is the angle between the light output from the output end of the output waveguide and the horizontal direction, arcsin is the inverse cosine trigonometric function, arctan is the inverse sine trigonometric function, sin() is the sine trigonometric function, f is the focal length, n eff is the effective refractive index of the core of the output waveguide, D i is the distance from the output end of the i-th output waveguide to the center output waveguide.

[0022] The angle of the output end of the output waveguide is the angle between the light output from the output end of the output waveguide and the horizontal direction, and the horizontal direction is a direction perpendicular to the detector plane.

[0023] The distance D from the output end of the i-th output waveguide to the center output waveguide i Set it according to the following formula:

[0024]

[0025] Wherein, d is the distance between the output ends of two adjacent output waveguides, and N is the number of output waveguides.

[0026] The innovation of the present invention lies in the design of the angle of the output end of the output waveguide and the length of the output waveguide to meet the phase condition, so that the light output by the output waveguide can be focused on the detector plane, while achieving the beneficial effects of enhancing spectral intensity, resolution and contrast and reducing crosstalk.

[0027] The beneficial effects of the present invention are:

[0028] The tilt angle of the output light beams of each output waveguide in the present invention increases the degree of overlap between the diffraction fields of each output waveguide at the detector plane, so that the present invention can achieve the focusing and dispersion functions of the output light beam while enhancing the intensity, resolution and contrast of the spectrum. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 (a) is a schematic diagram of the improved arrayed waveguide grating spectrometer chip of the present invention;

[0030] Figure 1(b) is a schematic diagram of the output end of the output waveguide of the present invention;

[0031] Figure 1 (c) is a diagram illustrating how the structures of the two outermost output waveguides and the middle output waveguide of the present invention are changed to allow the centers of the diffraction fields to overlap when light is sequentially transmitted therethrough;

[0032] Figure 2 This is a diagram of the light field intensity after light propagates through the free propagation block waveguide in Example 2 of the present invention;

[0033] Figure 3 Schematic diagram illustrating the structure of the improved arrayed waveguide grating spectrometer chip in Example 2 of the present invention;

[0034] Figure 4 This is a simulated spectrum diagram in Example 2 of the present invention;

[0035] Figure 5 This is a simulation spectrum diagram in comparative example 1 of the present invention. DETAILED DESCRIPTION

[0036] The present invention is described in more detail below with reference to the accompanying drawings and examples. However, the present invention is not limited thereto. A person skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are considered to be within the scope of protection of the present invention. Any matters not described in detail in this specification constitute prior art known to those skilled in the art.

[0037] like Figure 1 As shown in (a), the improved arrayed waveguide grating spectrometer chip of embodiment 1 of the present invention comprises:

[0038] A substrate 1 and an input waveguide 2, a free propagation block waveguide 3, and a waveguide array arranged on the substrate 1. The waveguide array is mainly composed of a plurality of output waveguides 4 arranged in an array at intervals. The input waveguide 2, the free propagation block waveguide 3, and the output waveguide 4 are arranged in sequence along the propagation direction of light. The input end and the output end of the input waveguide 2 are respectively coupled to an external light source and the input end of the free propagation block waveguide 3. The output end of the free propagation block waveguide 3 is respectively coupled to the input ends of a plurality of output waveguides 4. The output light of the output end of each output waveguide 4 is irradiated onto an external detector plane.

[0039] The angles of the output ends of the output waveguides 4 are different from each other.

[0040] like Figure 1 (b) is a schematic diagram showing the output end of the output waveguide of this embodiment.

[0041] like Figure 1(c) is a diagram showing how the centers of the diffraction fields overlap by changing the structure when the two outermost output waveguides and the middle output waveguide of the present invention pass light in sequence.

[0042] The light source emits light, which is coupled with the input end of the input waveguide 2 after propagating through the optical fiber, enters the input waveguide 2 for propagation, propagates through the free propagation block waveguide 3, reaches the input end of the output waveguide 4, and is then output from the output end of the output waveguide 4 to illuminate the detector plane.

[0043] The free propagation block waveguide 3 is the free propagation area of ​​the light beam in the spectrometer.

[0044] Several output waveguides 4 constitute a waveguide array.

[0045] In a specific implementation, the end face of the input end of the input waveguide 2 is flush with one end face of the substrate 1 , and the end face of the output end of each output waveguide 4 is flush with the other end face of the substrate 1 .

[0046] The material of the substrate 1 is glass, silicon nitride, lithium niobate, gallium arsenide, indium phosphide or silicon.

[0047] The output end of the free propagation block waveguide 3 is a circular arc end face.

[0048] The output waveguide 4 is a curved waveguide or a broken line waveguide.

[0049] The tangential direction of the output end of the free propagation block waveguide 3 is not parallel to the output end of each output waveguide 4 .

[0050] The lengths of the output waveguides 4 increase in sequence.

[0051] The lengths of the output waveguides 4 are set according to the following formula:

[0052] l i =P i -P1+(i-1)ΔL+l1

[0053]

[0054] Among them, l i is the length of the i-th output waveguide 4, l1 is the length of the first output waveguide 4, i is the index, P i -P1 is the optical path difference that the i-th output waveguide 4 needs to satisfy relative to the first output waveguide 4 to realize the convex lens focusing function, ΔL is the length difference that needs to be satisfied between adjacent output waveguides 4 to realize the dispersion function, m is the spectral order of the improved arrayed waveguide grating spectrometer chip, λ c is the central wavelength of the improved arrayed waveguide grating spectrometer chip, P iis the focal length f minus the distance from the light emitted by the i-th output waveguide 4 to the detector plane to form the interference surface, P1 is the focal length f minus the distance from the light emitted by the first output waveguide 4 to the detector plane to form the interference surface, n eff is the effective refractive index of the core of the output waveguide 4, f is the focal length, and D i is the distance from the output end of the i-th output waveguide 4 to the center output waveguide.

[0055] The focal length f is the focal length required for the detector plane to achieve exact focus.

[0056] The central output waveguide 4 is the middlemost output waveguide 4 among all the output waveguides 4 .

[0057] The focusing function of the convex lens is realized so that the output waveguide 4 can be focused exactly on the detector plane.

[0058] The angle of the output end of the output waveguide 4 is set according to the following formula:

[0059]

[0060] Among them, λ i is the angle between the light output from the output end of the output waveguide 4 and the horizontal direction, arcsin is the inverse cosine trigonometric function, arctan is the inverse sine trigonometric function, sin() is the sine trigonometric function, f is the focal length, n is the focal length, eff is the effective refractive index of the core of the output waveguide 4, D i The output end of the i-th output waveguide 4 is connected to D i is the distance from the output end of the i-th output waveguide 4 to the center output waveguide.

[0061] The angle of the output end of the output waveguide 4 is the angle between the light output from the output end of the output waveguide 4 and the horizontal direction, where the horizontal direction is a direction perpendicular to the detector plane.

[0062] The distance D between the output end of the i-th output waveguide 4 and the center output waveguide 4 i Set it according to the following formula:

[0063]

[0064] Wherein, d is the distance between the output ends of two adjacent output waveguides 4 , and N is the number of output waveguides 4 .

[0065] Example 2

[0066] S1. Design of free propagation block waveguide 3.

[0067] The arc radius R0 of the output end of the free propagation block waveguide 3 is selected to be 6000 μm, and the central wavelength λ of the improved arrayed waveguide grating spectrometer is selected to bec = 1.550μm. This requires that when the light beam propagates through the input waveguide into the free propagation block waveguide 3 and reaches the input end face of the output waveguide 4, its optical field width should be smaller than the width of the input end face. For the transmission mode of the output waveguide 4, its transverse and longitudinal full width at half maximum (FWHM) are:

[0068] ω L =dx(2ln2) 1 / 2 (0.321+2.1W -3 / 2 +4W -6 )

[0069] ω T =dy(2ln2) 1 / 2 (0.321+2.1D -3 / 2 +4D -6 )

[0070]

[0071] Among them, ω L is the lateral full width at half maximum of the transmission mode of output waveguide 4, ω T is the longitudinal full width at half maximum of the transmission mode of the output waveguide 4, k0 represents the wave number, W is called the transverse normalized frequency of the optical waveguide, D is called the longitudinal normalized frequency of the optical waveguide, dx and dy are the transverse width and longitudinal height of the core of the output waveguide 4, and n1 and n2 are the core refractive index and cladding refractive index of the output waveguide 4, respectively. eff is the effective refractive index of the fiber core. After the propagation distance R0, the field distribution at R0 is:

[0072]

[0073] Among them, E i () represents the field distribution at R0, α represents the product of wavelength and focal length in Fourier optical propagation, λ represents the wavelength of the propagating light wave, and x ′ Represents the coordinates at R0.

[0074] Calculate the x corresponding to the function value where the function value drops to 1 / e of the maximum value ′ Thus, the 1 / e width can be calculated. In the example provided by the present invention, the width of the output waveguide 4 is 6.1 microns. For light with a wavelength of 1550 nanometers, the refractive indices of the core and cladding are 1.4548 and 1.4440 respectively. f =6000,λ=1.550μm, the field distribution of TE mode is as follows Figure 2As shown, its 1 / e width is 375.1920 microns, and its optical field width is equal to twice the 1 / e width, which is 750.3840 microns. Therefore, the chord length of the arc end of the free propagation block waveguide 3 is selected to be 1750 microns, the spacing D0 between the input ends of each output waveguide 4 on the arc end surface of the free beam propagation block waveguide 3 is 12 microns, and the number of output waveguides 4 is 120.

[0075] S2. Design the waveguide array of the improved arrayed waveguide grating spectrometer chip.

[0076] The lengths of several output waveguides 4 in the S21 waveguide array satisfy the relationship.

[0077] For the improved arrayed waveguide grating spectrometer chip, it is necessary to achieve the dispersion function on top of the output beam focusing function. Therefore, the length of the four output waveguides needs to meet the following requirements:

[0078] l i -l1=P i -P1+(i-1)ΔL

[0079]

[0080] Among them, l i is the length of the i-th output waveguide 4, l1 is the length of the first output waveguide 4, i is the index, P i -P1 is the optical path difference that the i-th output waveguide 4 needs to satisfy relative to the first output waveguide 4 to achieve the convex lens focusing function, ΔL is the length difference that needs to be satisfied between adjacent output waveguides 4 to achieve the dispersion function, m is the spectral order of the improved arrayed waveguide grating spectrometer chip, λ c is the central wavelength of the improved arrayed waveguide grating spectrometer chip, P i is the focal length f minus the distance from the light emitted by the i-th output waveguide 4 to the detector plane to form the interference surface, P1 is the focal length f minus the distance from the light emitted by the first output waveguide 4 to the detector plane to form the interference surface, n eff is the effective refractive index of the core of the output waveguide 4, f is the focal length, and D i is the distance from the output end of the i-th output waveguide 4 to the central output waveguide, d is the distance between the output ends of two adjacent output waveguides 4, and N is the number of output waveguides 4.

[0081] The distance d between the output ends of two adjacent output waveguides 4 is selected to be 70 microns, and the focal length f is selected to be 70 microns. From this, the length P of the i-th output waveguide 4 used to realize the detector plane focusing function can be determined. i The length difference ΔL between adjacent output waveguides 4 and the free spectral range FSR of the improved arrayed waveguide grating spectrometer chip satisfy the following relationship:

[0082]

[0083] Where FSR is the free spectral range, c0 is the speed of light in vacuum, and n g is the group refractive index, satisfying the following relationship:

[0084]

[0085] The length difference ΔL between adjacent output waveguides 4 is finally selected to be 42.71919 μm.

[0086] S3. Design the angle of the output end of the output waveguide 4.

[0087] Define the angle γ between the light output from the output end of the i-th output waveguide 4 and the horizontal direction i The horizontal direction is the direction perpendicular to the detector plane, γ i The expression is:

[0088]

[0089] The calculated D i By substituting this formula into the equation, the angle between the light output from the output end of each output waveguide 4 and the horizontal direction can be calculated.

[0090] The light field intensity of the light in this embodiment after propagating through the free propagation block waveguide 3 is shown in FIG. Figure 2 shown.

[0091] S4, geometric design of output waveguide 4 of arrayed waveguide grating spectrometer.

[0092] S41. Structure of the output waveguide 4 device of the arrayed waveguide grating spectrometer.

[0093] like Figure 3 As shown, the center of the free propagation block waveguide 3 is defined as the coordinate origin, the horizontal direction is the x-axis direction, and the vertical direction is the y-axis direction; the horizontal direction is the direction perpendicular to the detector plane.

[0094] The angle between the line segment formed by connecting the midpoint of the arc end surface of the free propagation block waveguide 3 and the coordinate origin and the x-axis is θ, the angle between the line segment formed by connecting the midpoint of the arc end surface of the free propagation block waveguide 3 and the coordinate origin and the radius formed by the center of the input end of the first output waveguide 4 and the coordinate origin is α1, and the angle between the line segment formed by connecting the midpoint of the arc end surface of the free propagation block waveguide 3 and the coordinate origin and the radius formed by the center of the input end of the i-th output waveguide 4 and the coordinate origin is α i, the length of the line segment formed by connecting the point on the arc end surface of the free propagation block waveguide 3 and the coordinate origin is defined as L0, the line segment formed by connecting the midpoint of the arc end surface of the free propagation block waveguide 3 and the coordinate origin is defined as the rotation axis, the coordinate origin is the rotation center, and the α obtained by counterclockwise rotation is i Taking a negative value, the α obtained by rotating clockwise i The value is positive.

[0095] The first output waveguide 4 is composed of a straight waveguide 1, a circular arc waveguide, and a straight waveguide 2, connected in sequence: Straight waveguide 1: A waveguide extending from the center of the arc end face of the free propagation block waveguide 3, along a line at an angle θ-α1 with the x-axis, between two points at distances R0 and R0+L0+L1 from the center. In other words, straight waveguide 1 has a length of L1. The circular arc waveguide: A waveguide with a central angle of θ-α1+γ1 and a radius of R1. Straight waveguide 2: A waveguide with a length of K1 and an inclination angle of γ1.

[0096] The i-th output waveguide 4 is composed of a straight waveguide 1, an arc waveguide and a straight waveguide 2 connected in sequence: Straight waveguide 1: passes through the center of the arc end face of the free propagation block waveguide 3, and has an angle of θ-α with the x-axis i The distance between the straight line and the center of the circle is R0 and R0+L0+L i The length of the waveguide between the two points, that is, the straight waveguide is L i Circular arc waveguide: the central angle is θ-α i +γ i , with a radius of R i Straight waveguide 2: length is K i , the inclination angle is γ i waveguide.

[0097] The Nth output waveguide 4 is composed of a straight waveguide 1, an arc waveguide and a straight waveguide 2 connected in sequence: Straight waveguide 1: passes through the center of the arc end face of the free propagation block waveguide 3, and has an angle of θ-α with the x-axis N The distance between the straight line and the center of the circle is R0 and R0+L0+L N The length of the waveguide between the two points, that is, the straight waveguide is L N Circular arc waveguide: the central angle is θ-α N +γ N , with a radius of R N Straight waveguide 2: length is K N , the inclination angle is γ N waveguide.

[0098] The following relationship needs to be satisfied between the output waveguides 4:

[0099] The length of the i-th output waveguide 4 needs to satisfy l i -l1=P i -P1+(i-1)ΔL, so:

[0100] L i +(θ-α i +γ i )R i +K i -[L1+(θ-α1+γ1)R1+K1]=l i -l1

[0101] The output ends of the output waveguides 4 should be located on the same output end face, so:

[0102] (R0+L0+L i )cos(θ-α i )+R i sin(θ-α i )+R i sin(γ i )+K i cos(γ i )

[0103] -[(R0+L0+L1)cos(θ-α1)+R1 sin(θ-α1)+R1 sin(γ1)

[0104] +K1 cos(γ1)]=0

[0105] The spacing between the output ends of adjacent output waveguides 4 on the y-axis is equal, both d, so:

[0106] (R0+L0+L i )sin(θ-α i )+R i cos(γ i )-R i cos(θ-α i )-K i sin(γ i )

[0107] -[(R0+L0+L1)sin(θ-α1)-R1 cos(θ-α1)+R1 cos(γ1)

[0108] -K1 sin(γ1)]=(i-1)d

[0109] remember:

[0110] a s =θ-α i +γ i

[0111] b s =l i-l1+L1+(θ-α1+γ1)R1+K1

[0112] c s =(R0+L0+L1)cos(θ-α1)+R1 sin(θ-α1)+R1 sin(γ1)

[0113] +K1 cos(γ1)-(R0+L0)cos(θ-α i )

[0114] d s =(R0+L0+L1)sin(θ-α1)-R1 cos(θ-α1)+R1 cos(γ1)

[0115] +K1 sin(γ1)-(R0+L0)sin(θ-α i )+(i

[0116] -1)d

[0117] De=[cos(θ-α i )-cos(γ i )]·[-cos(θ-α i )+cos(γ i )

[0118] +a s sin(γ1)]-[sin(θ-α i )+sin(γ i )]

[0119] ·[sin(θ-α) i )+sin(γ i )-a s cos(γ i )]

[0120] Nu1=[c s -b s cos(γ i )]·[-cos(θ-α i )+cos(γ i )+a s sin(γ1)]

[0121] -[b s sin(γ i )+d s ]·[sin(θ-α i )+sin(γ i )

[0122] -a s cos(γ i )]

[0123] Nu2 = b s [cos(θ - α i )sin(γ i ) + sin(θ - α i )cos(γ i )]

[0124] -c s [sin(θ - α i ) + sin(γ i )] + d s [cos(θ - α i )

[0125] -cos(γ i )]

[0126] Nu3 = b s [-cos 2 (θ - α i ) - sin 2 (θ - α i )) - sin(θ - α i )sin(γ i )

[0127] +cos(θ - α i )cos(γ i )]

[0128] +c s [cos(θ - α i ) - cos(γ[[ID=II]] i ) - a s sin(θ - α i )]

[0129] +d s [sin(θ - α i ) + sin(γ i ) - a s cos(θ - α i )]

[0130] Thus, the solution is obtained:

[0131]

[0132] In the above formula, a s , b s , c s , d s , De, Nu1, Nu2, and Nu3 have no specific meaning and are only for convenient calculation.

[0133] S43. Selection and optimization of the initial value.

[0134] In this example, the parameters to be optimized are L1, R1, K1, and θ. After determining the parameters of the first output waveguide 4, the parameters of the subsequent output waveguides 4 can be calculated using the above formula. The scanning range of L1 is 0 to 3000 microns, the scanning range of R1 is 5000 to 50000 microns, the scanning range of K1 is 0 to 3000 microns, and the scanning range of θ is The minimum value of γ1 is to ensure the consistency of the arc orientation of the output waveguide 4. Table 1 shows the parameter values ​​after optimization. Substitute the optimized results into the above L i ,R i ,K i The calculation formula can be used to calculate the parameters of each output waveguide 4, and then according to the calculated parameters of each output waveguide 4, as shown in Table 1, a specific example of the improved arrayed waveguide grating spectrometer is produced, and its schematic diagram is shown in FIG. Figure 3 shown.

[0135] Table 1 Parameters of improved arrayed waveguide grating spectrometer

[0136] <![CDATA[R0]]> 6000μm ΔL 42.7192μm N 120 <![CDATA[L1]]> 0 <![CDATA[D0]]> 12μm <![CDATA[R1]]> 29206.5669μm d 70μm <![CDATA[K1]]> 3000μm f 50000μm θ 0.7461446

[0137] The spectrum obtained by simulation in Example 2 is as follows Figure 4 shown.

[0138] Comparative Example 1

[0139] Using the same parameters as in Example 2, only the output angles of all output waveguides 4 are changed to be horizontal. The spectrum obtained by simulation is as follows: Figure 5 shown.

[0140] Figure 5 and Figure 4 The following are spectra obtained by simulating the arrayed waveguide grating spectrometer in Comparative Example 1 of the prior art and the improved arrayed waveguide grating spectrometer in Example 2 of the present invention. The horizontal axis in each figure represents the wavelength corresponding to the light spot, and the vertical axis represents the normalized intensity. The insets all represent spectra of light with a wavelength of 1550 nanometers, i.e., the center wavelength. The coordinate of the vertical dashed line on the x-axis in the inset represents the wavelength corresponding to when the light field intensity drops to 1 / e of the maximum value. The wavelength interval set in the simulation is 0.5 nanometer. Based on the simulation results, the intensity of the spectral fringes, the 1 / e width of the light field, and the crosstalk of the two cases were calculated. The comparison results are as follows: Under this set of parameters, compared with the arrayed waveguide grating spectrometer of the prior art, the spectral fringes intensity of the improved arrayed waveguide grating spectrometer proposed in the present invention is increased by 99.96%, the 1 / e width of the fringes is reduced by 18.78%, and the crosstalk is reduced by 140.94%. While improving the brightness of the spectral fringes, the resolution and contrast of the fringes are also improved.

[0141] The innovation of the present invention lies in the design of the angle of the output end of the output waveguide and the length of the output waveguide to meet the phase condition, so that the light output by the output waveguide can be focused on the detector plane, while achieving the beneficial effects of enhancing spectral intensity, resolution and contrast and reducing crosstalk.

[0142] Those skilled in the art will understand that the above is merely an example of the invention and is not intended to limit the invention. Although the invention has been described in detail with reference to the above example, those skilled in the art may modify the technical solutions of the above example or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the invention shall be included within the scope of protection of the invention.

Claims

1. An improved arrayed waveguide grating spectrometer chip, characterized by: The invention comprises a substrate (1), an input waveguide (2), a free propagation block waveguide (3), and a waveguide array arranged on the substrate (1); the waveguide array is mainly composed of a plurality of output waveguides (4) arranged in an array at intervals; the input waveguide (2), the free propagation block waveguide (3), and the output waveguide (4) are arranged in sequence along the propagation direction of light; the input end and the output end of the input waveguide (2) are respectively coupled to the light source and the input end of the free propagation block waveguide (3); the output end of the free propagation block waveguide (3) is respectively coupled to the input ends of the plurality of output waveguides (4); and the output light of the output end of each output waveguide (4) is irradiated on the detector plane; The angles of the output ends of the output waveguides (4) are different from each other.

2. The improved arrayed waveguide grating spectrometer chip according to claim 1, characterized in that: The material of the substrate (1) is glass, silicon nitride, lithium niobate, gallium arsenide, indium phosphide or silicon.

3. The improved arrayed waveguide grating spectrometer chip according to claim 1, characterized in that: The output end of the free propagation block waveguide (3) is a circular arc end face.

4. The improved arrayed waveguide grating spectrometer chip according to claim 1, characterized in that: The output waveguide (4) is a curved waveguide or a broken line waveguide.

5. The improved arrayed waveguide grating spectrometer chip according to claim 1, characterized in that: The tangent direction of the output end of the free propagation block waveguide (3) is not parallel to the output end of each output waveguide (4).

6. The improved arrayed waveguide grating spectrometer chip according to claim 1, characterized in that: The lengths of the plurality of output waveguides (4) increase in sequence.

7. The improved arrayed waveguide grating spectrometer chip according to claim 1, characterized in that: The lengths of the plurality of output waveguides (4) are set according to the following formula: l i =P i -P1+(i-1)ΔL+l1 Among them, l i is the length of the i-th output waveguide (4), l1 is the length of the first output waveguide (4), i is the index, P i -P1 is the optical path difference required for the ith output waveguide (4) to realize the convex lens focusing function relative to the first output waveguide (4), ΔL is the length difference required for adjacent output waveguides (4) to realize the dispersion function, m is the spectral order of the improved arrayed waveguide grating spectrometer chip, λ c is the central wavelength of the improved arrayed waveguide grating spectrometer chip, P i is the focal length f minus the distance from the light emitted by the i-th output waveguide (4) to the detector plane to form the interference surface, P1 is the focal length f minus the distance from the light emitted by the first output waveguide (4) to the detector plane to form the interference surface, n eff is the effective refractive index of the core of the output waveguide (4), f is the focal length, and D i is the distance from the output end of the i-th output waveguide (4) to the central output waveguide (4).

8. The improved arrayed waveguide grating spectrometer chip according to claim 1, characterized in that: The angle of the output end of the output waveguide (4) is set according to the following formula: Among them, γ i is the angle between the light output from the output end of the output waveguide (4) and the horizontal direction, arcsin is the inverse cosine trigonometric function, arctan is the inverse sine trigonometric function, sin() is the sine trigonometric function, f is the focal length, n is the focal length, eff is the effective refractive index of the core of the output waveguide (4), D i is the distance from the output end of the i-th output waveguide (4) to the central output waveguide (4).

9. The improved arrayed waveguide grating spectrometer chip according to claim 8, characterized in that: The distance D between the output end of the i-th output waveguide (4) and the central output waveguide (4) i Set it according to the following formula: Wherein, d is the distance between the output ends of two adjacent output waveguides (4), and N is the number of output waveguides (4).

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