One-dimensional photonic crystal cascaded slot waveguide for silicon heterogeneous integration

Abstract

The embodiment of the present application provides a one-dimensional photonic crystal cascade slot waveguide for silicon hetero integration, and belongs to the technical field of optoelectronic devices.The slot waveguide comprises: a monocrystalline silicon layer, which constitutes the body of the slot waveguide; a slot, which is arranged on the monocrystalline silicon layer; and a defect part, which is periodically arranged in the one-dimensional photonic crystal slot waveguide, and constitutes a resonant cavity of the one-dimensional photonic crystal cascade slot waveguide, thereby forming a cascade resonant unit of the one-dimensional photonic crystal cascade slot waveguide.The one-dimensional photonic crystal cascade slot waveguide has an optical bandwidth superior to that of a two-dimensional photonic crystal structure, and has lower transmission loss and better processing robustness.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic device technology, and in particular to a one-dimensional photonic crystal cascaded slit waveguide for silicon heterogeneous integration. Background Technology

[0002] In recent years, driven by silicon-based optoelectronic technology, achieving "optoelectronic synergy" at the chip scale has become a development trend in the "post-Moore's Law era" of chips. As a crucial component connecting electrical information processing and optical signal transmission, electro-optic modulators play a vital role in optical modules. To improve the performance of existing data communication networks, it is necessary to realize electro-optic modulators with high bandwidth, small size, and low power consumption. The performance of electro-optic modulators depends on the strength of the interaction between the working material and the propagating light wave mode. Based on the platform used to achieve electro-optic modulation, they are classified into lithium niobate modulators, silicon-based modulators, indium phosphide modulators, organic polymer modulators, etc. Existing electro-optic modulators are approaching their physical bottlenecks in terms of bandwidth, size, and power consumption. Since these bottlenecks are mainly determined by the physical properties and mechanisms of materials and devices, achieving leapfrog development requires breaking through the single material system and device mechanism of existing electro-optic modulators. Therefore, heterogeneous integrated electro-optic modulators based on novel electro-optic materials and waveguide mechanisms still have enormous research potential.

[0003] Most silicon-based electro-optic modulators are based on the plasmonic dispersion effect. However, the weak dispersion effect of silicon plasmons means that traditional Mach-Zehnder modulators are typically millimeter-long and require bias voltages of several volts. Furthermore, the optical bandwidth of the device is limited not only by the electro-optic signal speed mismatch but also by free carrier dynamics. Resonator-based silicon modulators offer more compact size and lower power consumption. However, they typically require additional electronic feedback control with heaters to maintain the stability of the operating wavelength. To improve modulation efficiency and speed, other materials with electro-optic effects have been researched and applied. Lithium niobate electro-optic modulators are widely used in ultra-long-range communication due to their low loss, high operating wavelength bandwidth, and good stability. Electro-optic polymers, with their larger electro-optic coefficients, show great potential in fabricating small-size, low-power electro-optic modulators. Moreover, EO polymers have a phase response time of only 30 femtoseconds, and many reports indicate bandwidths exceeding 60 GHz. Currently, research is being conducted on the selection of electro-optic polymers, their manufacturing processes, polarization, and how to heterogeneously integrate silicon and electro-optic organic polymers to leverage their respective advantages.

[0004] In traditional silicon-organic polymer heterogeneous integrated devices, most of the optical field is confined within the high-refractive-index silicon, with only a small fraction of the light confined within the cladding polymer. This results in a very low actual electro-optic effect, limiting device size to millimeters. Slit waveguides are commonly used to mitigate this phenomenon because the refractive index of the electro-optic polymer within the slit is lower than that of silicon, enhancing the optical modes within it. However, due to the small slit width, the polarization efficiency of the electro-optic polymer is difficult to achieve ideal levels, leading to a still low actual electro-optic coefficient for the device. Besides using slit waveguides, the propagation speed of the light field can be reduced to increase the interaction time between the light and the electro-optic polymer. Photonic crystal waveguides, such as two-dimensional (2D) and one-dimensional (1D) photonic crystal waveguides, utilize the slow-light effect to enhance the interaction between light and matter. Under current process conditions, the fabrication robustness of 2D photonic crystals is poor. Literature indicates that even a 1% fluctuation in hole radius can lead to an optical loss of 150 dB / cm. Compared to 2D photonic crystals, 1D photonic crystals are more tolerant of fabrication errors and often utilize CMOS-compatible manufacturing processes. Two key challenges need to be addressed in one-dimensional photonic crystals: higher-order dispersion and the delay-bandwidth product. Higher-order dispersion can be reduced by using two photonic crystal waveguides with opposite dispersion characteristics, or by using zero-dispersion slow-light devices to suppress signal distortion. The delay-bandwidth product implies that the group velocity of light needs to be balanced with the optical bandwidth. This can be addressed by using coupled resonators to increase the optical bandwidth, making the waveguide less sensitive to temperature and allowing for a wider operating temperature range. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a one-dimensional photonic crystal cascaded slit waveguide for silicon heterogeneous integration, which at least partially solves the problems existing in the prior art.

[0006] This invention provides a one-dimensional photonic crystal cascaded slit waveguide for silicon heterointegration, comprising:

[0007] A single-crystal silicon layer, which constitutes the body of the slit waveguide;

[0008] A slit, the slit being disposed on the monocrystalline silicon layer;

[0009] The defective part is periodically arranged in the one-dimensional photonic crystal slit waveguide. The defective part constitutes the resonant cavity of the one-dimensional photonic crystal cascaded slit waveguide, thereby forming the cascaded resonant unit of the one-dimensional photonic crystal cascaded slit waveguide.

[0010] According to one specific implementation of this disclosure, the slit is filled with an electro-optic organic polymer.

[0011] According to one specific implementation of this disclosure, the slit waveguide includes a ridge waveguide with a height of 220 nm.

[0012] According to one specific implementation of this disclosure, the defect portion is formed by uniformly introducing a π phase shift.

[0013] According to one specific implementation of this disclosure, the slit waveguide includes silicon rails and silicon teeth.

[0014] According to one specific implementation of this disclosure, the duty cycle of the resonant unit is 50%.

[0015] According to one specific implementation of the present disclosure, each resonant unit consists of a one-dimensional photonic crystal slit waveguide with a period of 2NOP and a phase shift of π, and the defect length is half a period.

[0016] According to a specific implementation of this disclosure, the evaluation factor for the influence of waveguide optical structure on modulation performance is defined as follows:

[0017]

[0018] The change in effective refractive index in a slit waveguide structure is expressed as:

[0019]

[0020] Among them, V π The phase shift voltage is represented by λ, the modulator length by L, the preset parameters by λ, and the slit width by Ws. 33 n is the electro-optic coefficient of the electro-optic polymer. EO Γ is the effective index of the electro-optic polymer without electro-optic effect, and U is the bias voltage applied across the slit. slot,y It is the field interaction factor of the TE0 mode.

[0021] According to a specific implementation of an embodiment of this disclosure, Γ slot,y Calculated using formula (3):

[0022]

[0023]

[0024]

[0025] ε is the relative permittivity of the material and the integration region, n g It is the group refractive index of the modes, Γ OCF G is the light field energy confinement factor in the slit region. n It is a time factor.

[0026] According to one specific implementation of this disclosure, the trade-off between optical bandwidth and group refractive index is described by the time-delay-bandwidth product:

[0027]

[0028]

[0029] Where, Δt=n g L / c represents the delay after the optical transmission length L, f = w / 2π, Δf is the bandwidth centered at the bandwidth f, and Δn eff It is the refractive index change corresponding to the normalized bandwidth Δf / f.

[0030] This invention provides a one-dimensional photonic crystal cascaded slit waveguide for silicon heterogeneous integration, comprising: a monocrystalline silicon layer forming the body of the slit waveguide; a slit disposed on the monocrystalline silicon layer; and defect portions periodically disposed within the one-dimensional photonic crystal slit waveguide, forming a resonant cavity of the one-dimensional photonic crystal cascaded slit waveguide, thereby forming a cascaded resonant unit of the one-dimensional photonic crystal cascaded slit waveguide. The one-dimensional photonic crystal cascaded slit waveguide of this solution has a superior optical bandwidth compared to two-dimensional photonic crystal structures, and also exhibits lower transmission loss and better fabrication robustness. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1a -d is a schematic diagram of a one-dimensional photonic crystal cascaded slit waveguide structure and optical field energy for silicon heterointegration provided in an embodiment of the present invention;

[0033] Figure 2 Transmission curve of a one-dimensional photonic crystal cascaded slit waveguide provided in an embodiment of the present invention;

[0034] Figure 3 The slit width W under different coupling coefficients provided in the embodiments of the present invention S Energy confinement factor Γ of the light field OCF Impact diagram;

[0035] Figure 4 W provided for embodiments of the present invention T and W R Changes with respect to time factor G n and light field energy constraint factor ΓOCF Trend chart of changes;

[0036] Figure 5 A schematic diagram illustrating the effect of increasing NOP on the field interaction factor according to an embodiment of the present invention;

[0037] Figure 6 The width W of the slit provided in the embodiments of the present invention S Guide rail width W R The length W of the teeth T A schematic diagram illustrating the impact on optical bandwidth. Detailed Implementation

[0038] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0039] Figure 1a , Figure 1b , Figure 1c The waveguide structure proposed in this invention is shown, comprising an organic polymer 10, a single-crystal silicon layer 20, and silicon dioxide 30. By periodically introducing defects into the one-dimensional photonic crystal slit waveguide, a narrow passband is opened within the original photonic bandgap of the one-dimensional photonic crystal slit waveguide. The defects in the one-dimensional photonic crystal are formed by uniformly introducing a π phase shift, which is equivalent to uniformly introducing a resonant cavity, thereby forming a coupled resonant cavity slit waveguide. Each resonant cavity has a high quality factor, which is beneficial for reducing the group velocity, and simultaneously forms a transmission peak with a large group refractive index and a relatively wide and flat optical bandwidth near the center wavelength of the transmission spectrum. The large group refractive index is beneficial for light-matter interaction; on the other hand, filling the slit with an electro-optic organic polymer, such as... Figure 1a , Figure 1b As shown, since the refractive index of the electro-optic polymer in the slit is less than that of silicon, the light field in the slit will be enhanced according to the continuity of the electric displacement vector, thereby improving the interaction between light and the electro-optic polymer.

[0040] Figure 1c It consists of NOR resonant units comprising a cascaded one-dimensional photonic crystal slit waveguide. Its period and duty cycle are Λ and 50%, respectively, and the slit width is W. S The width of the silicon guide rail is W. R Tooth width is W T The ridge waveguide has a height of 220 nm. The silicon substrate has a height of 70 nm and a width of 3000 nm to facilitate subsequent carrier doping and electrode connections. A one-dimensional photonic crystal cascaded slit waveguide is located on a silicon dioxide layer and filled with electro-optic materials such as organic polymers, lithium niobate films, or lithium titanate films—materials with high electro-optic coefficients—both inside and above the slot. Each resonant unit consists of a one-dimensional photonic crystal slit waveguide with a period of 2 NOP and a π phase shift; the defect length is half a period. Figure 1dThe optical field energy is mainly distributed in the middle region of the waveguide, and it can also be seen that the optical field in the slit region is relatively enhanced. These factors help to increase the field interaction factor in the later stage.

[0041] Figure 2 (a) is the transmission curve of a one-dimensional photonic crystal cascaded slit waveguide. A transmission peak with a bandwidth of several nanometers appears in the middle region of the original photonic bandgap. A larger bandwidth can reduce the sensitivity to factors such as ambient temperature, thereby enhancing the stability of the device operation. Figure 2 (b) The pink solid line represents the group refractive index corresponding to different wavelengths in the one-dimensional photonic crystal cascaded slit waveguide. It can be seen that the group refractive index near the center wavelength is about 9, and the group refractive index at the edge of the transmission peak is as high as 18, which is several times the group refractive index in the traditional slit waveguide. This is very beneficial to the interaction between the optical field and the electro-optic polymer in the slit. Figure 2 (b) The orange solid line is the group velocity dispersion curve. Near the center wavelength, the group velocity dispersion is almost equal to 0. At this time, the one-dimensional photonic crystal cascaded slit waveguide can be regarded as a zero-dispersion structure, and the output optical signal can maintain the input waveform well. However, although the group refractive index of the band edge is larger, the corresponding group velocity dispersion is also very large, which will seriously distort the output optical signal and is not conducive to the reception and signal processing of the subsequent system.

[0042] The characteristics of the transmission peak of a one-dimensional photonic crystal cascaded slit waveguide are related to various parameters. For example, the bandgap width of a one-dimensional photonic crystal slit waveguide is related not only to the coupling coefficients of the forward and backward modes but also to the length of the one-dimensional photonic crystal slit waveguide. To improve the optical bandwidth of the transmission peak, it is usually necessary to reduce the coupling coefficients of the forward and backward modes. Therefore, to optimize the field interaction factor, it is necessary to comprehensively consider various structural parameters of the one-dimensional photonic crystal cascaded slit waveguide.

[0043] Modulation efficiency V π L is a crucial parameter for measuring the performance of on-chip electro-optic modulators. It is the product of the modulator length and the phase-shift voltage. When using an equal-arm Mach-Zehnder interferometer, the modulation efficiency is primarily influenced by the refractive index of the electro-optic polymer, the electro-optic coefficient, the field interaction factor of the waveguide structure, and the distance between the electrodes. To more generally fill various electro-optic polymers in the slit, the model focuses more on the influence of the waveguide optical structure on the modulation performance. Therefore, in the model, the evaluation factor is defined as:

[0044]

[0045] In this invention, when a bias voltage is applied to both sides of the silicon substrate, the electro-optic polymer will generate the Paulcks effect, resulting in a change in the effective refractive index of the waveguide. This change can be applied to phase modulation and amplitude modulation. Assuming that this change only occurs within the slit region, and the refractive index remains unchanged elsewhere, the change in the effective refractive index of the slit waveguide structure can be approximated as:

[0046]

[0047] Where, r 33 n is the electro-optic coefficient of the electro-optic polymer. EO W is the effective index of electro-optic polymers without electro-optic effects. d Γ is the width of the slit, and U is the bias voltage applied to both sides of the slit. slot,y It is the field interaction factor of the TE0 mode, which can be calculated by formula (3). The direction of the electric field is parallel to the main axis of the electro-optic polymer, that is, the y-axis of the waveguide coordinate system.

[0048]

[0049]

[0050]

[0051] ε is the relative permittivity of the material and the integration region, n g It is the group refractive index of the modes. Therefore, the field interaction factor Γ slot,y It can be viewed as the product of two terms: the first term is the time factor G. n The first term is related to the mode group refractive index, reflecting the influence of the optical field velocity on the field interaction. For a waveguide of a certain length, a smaller group velocity means a longer time for light to pass through the medium and an increased time for interaction with the electro-optic polymer, thus contributing more to the change in the cross-sectional refractive index. The second term is the optical field energy confinement factor Γ in the slit region. OCF It reflects the proportion of the light field that actually interacts with the electro-optic polymer within the slit at the cross-section. Clearly, Γ OCF The maximum value will not exceed 1; and for the time factor G n As long as the speed of the light field in the medium is effectively reduced, G n The value can be much greater than 1. Therefore, it is very valuable to study how to reduce the optical field velocity and thus increase the field interaction factor without sacrificing other modulation properties.

[0052] Obviously, the width W of the slit S This has a direct impact on the energy confinement factor of the light field. First, several sets of different guide rail widths W are selected to ensure the existence of optical modes. R The length W of the teeth TSimulation of slit width W under different coupling coefficients S Energy confinement factor Γ of the light field OCF The impact. For example... Figure 3 (a)(b), as the slit width W S The increase of time factor G n and light field energy constraint factor Γ OCF The trends of change are completely opposite. Light field energy constraint factor Γ OCF The decrease is due to the fact that the electric field distribution in the slit region is very rapid along the main axis of the electro-optic polymer, causing the electric field at the center of the slit region to decay to zero. This means that only a small area very close to the silicon rail has optical energy, and this phenomenon becomes more pronounced as the slit width increases. For the time factor G... n Within the same period, a high-contrast refractive index increases the coupling coefficient of the forward and backward modes, leading to a decrease in the forward propagation speed of light field energy, thereby increasing the time factor G. n .like Figure 3 (c) The gray curve, when the slit width W S At Γ = 100 nm, the field interaction factor reaches its maximum value. The evaluation factor FoM depends not only on the field interaction factor Γ slot,y Also related to the slit width W S Related. For example Figure 3 (d) As shown by the red solid line, when W S At 60nm, FOM = 1.85 × 10⁻⁶. -7 In actual devices and subsequent simulations, the sidewall loss of the slit increases as the slit width decreases. However, with advancements in fabrication technology, this optical loss is expected to decrease further. Considering both the sidewall loss and the evaluation factor FOM, the slit width of the one-dimensional photonic crystal cascaded slit waveguide is determined to be W. S After setting the value to 100nm, the tooth length W is then optimized. T Width W of the guide rail R .like Figure 4 As shown in (a)(b), when W T and W R When it changes, the time factor G n and light field energy constraint factor Γ OCF The changing trend is also the opposite. Regarding the light field energy confinement factor: when the slit width W... S At a given time, the width W of the silicon guide rails on both sides R The increase in the refractive index naturally leads to more light field being confined within the high-refractive-index silicon, which in turn reduces the proportion of light field energy within the slit, i.e., reduces the light field energy confinement factor. On the other hand, for the time factor G... nWithin the same period, a high-contrast refractive index increases the coupling coefficient of the forward and backward modes, leading to a decrease in the forward propagation speed of light field energy, thereby increasing the time factor G. n .like Figure 4 As shown in (c), the field interaction factor varies with the length W of the tooth. T The reduction or the width W of the guide rail R The increase in the coupling coefficients of the forward and backward modes also means that a larger coupling coefficient is more beneficial to improving the field interaction factor Γ. OCF .like Figure 4 As shown in (d), the lowest achievable evaluation factor in the simulation is FoM = 1.15 × 10⁻⁶. -7 This value is significantly lower than that of conventional silicon-organic hybrid integrated modulators currently employing slit waveguides. These comparisons preliminarily demonstrate the enormous potential of one-dimensional photonic crystal cascaded slit waveguides to improve the interaction between light and electro-optic polymers. Optical field energy confinement factor Γ OCF The changes are limited. Once W... S W R W T Once the values ​​are determined, according to photonic crystal theory, the optical modes supported by the waveguide structure are also determined. If the structural parameters remain unchanged, but only the period number NOP and the cascade number NOR of the one-dimensional photonic crystal cascaded slit waveguide are changed, Figure 5 As shown in (a) and (b), increasing NOP has a significant impact on the field interaction factor, while increasing NOR has a very small impact. On the one hand, when NOP is large, increasing NOP does not change the coupling coefficients of the forward and backward modes and the coupling between adjacent resonant cavities is weak, but it greatly increases the number of couplings between the forward and backward modes. Macroscopically, this manifests as a slower forward transmission of optical energy, thereby increasing the group refractive index and time factor G of the mode. n On the other hand, while increasing the number of NOR cascades has almost no effect on increasing the field interaction factor, it is very beneficial for reducing the bias voltage and thus reducing static power dissipation, because the half-wave voltage of the accumulated π phase will be lower. It is easy to see from the above analysis that a smaller W... S W T With W R A higher ratio or a larger number of periods (NOP) is more conducive to a smaller evaluation factor (FoM), which in turn is more conducive to the interaction between light and electro-optic polymers, improving the modulation efficiency of the device and achieving a modulator with lower power consumption and smaller size. However, further research will reveal that these ultra-high performances often come at the cost of sacrificing optical bandwidth.

[0053] e. Besides group refractive index, optical bandwidth is also an important parameter for measuring the slow-light effect of a device. Optical bandwidth (Δλ) BWThe group refractive index (RRI) is defined as the spectral width corresponding to a group refractive index no more than 10% of the group refractive index at the center frequency. If the optical bandwidth is small (severe group velocity dispersion), the output optical signal is prone to distortion, crosstalk, and poor device operating temperature stability. On the other hand, a large optical bandwidth is not always better because (when n...) g >>n) When the refractive index change of the material does not exceed 0.1, a larger optical bandwidth means a lower change in the group refractive index. The trade-off between optical bandwidth and group refractive index can be described by the concept of the time delay-bandwidth product (2.13).

[0054]

[0055]

[0056] Where, Δt=n g L / c represents the delay after the optical transmission length L, f = w / 2π, Δf is the bandwidth centered at the bandwidth f, and Δn eff This represents the refractive index change corresponding to the normalized bandwidth Δf / f. The time-delay-bandwidth product more comprehensively reflects the performance of slow-light devices, indicating that to obtain a larger group refractive index change, the bandwidth must be reduced; conversely, to obtain a larger bandwidth, the group refractive index change must be reduced. If it is desired to simultaneously increase the group refractive index and bandwidth of a one-dimensional photonic crystal slit waveguide, a larger effective refractive index change Δn must be designed. eff Combining (3) and (6), it is not difficult to see that the optical bandwidth of a one-dimensional photonic crystal cascaded slit waveguide is Γ-dependent on the optical field energy confinement factor. OCF Proportional. Figure 6 (a) and (b) show the width W of the slit. S Guide rail width W R The length W of the teeth T The impact on optical bandwidth. It can be observed that the trend of optical bandwidth variation is similar to that of the optical field confinement factor. In the red solid line, even when W... S =60nm optical bandwidth can reach 6nm, which is very beneficial for increasing the operating temperature range of one-dimensional photonic crystal cascaded slit waveguides.

[0057] According to formula (6), it can also be seen that increasing the number of cascades (NOR) leads to a greater time delay, while the optical mode remains unchanged. This means that Δn eff It does not change significantly with the change of NOR, so the optical bandwidth remains almost constant, thereby enhancing the delay-bandwidth product. Figure 6 (c) precisely matches this pattern extracted from the formula.

[0058]

[0059] When NOP is small, ng It is still very close to n, but does not satisfy n g >> this condition. From formulas (3) and (6), we know Δn eff It is a with n g A small change that is proportional to n, and much smaller than n, therefore when n g When it increases, Δn eff It will also increase proportionally. Since n is still greater than Δn at this point... eff Much larger, so n can be considered to have hardly changed. To maintain the equation, the normalized bandwidth Δf / f must be reduced, meaning the optical bandwidth will decrease. For example... Figure 6 (c) precisely reflects that the optical bandwidth Δf decreases as NOP increases. To balance the optical bandwidth and scattering loss caused by longer transmission distances, NOR should not be too large. When NOR = 7 and NOP = 12, the optical bandwidth can still reach 4.7 nm.

[0060] For the present invention, a smaller W S W T With W R A higher ratio or a higher number of periods (NOP) is more conducive to a smaller evaluation factor (FoM), which in turn is more conducive to the interaction between light and electro-optic polymers, improving the modulation efficiency of the device. However, this improvement comes at the cost of sacrificing optical bandwidth. Therefore, to comprehensively consider the modulation efficiency and optical bandwidth of the modulator, when selecting: NOP = 12, NOR = 7, W... S =100nm, W R =260nm and W T At 250nm, FoM = 2.87 × 10 -7 ,Δλ BW =4.7nm, lower than other non-slow-light devices, with a waveguide length of only 56μm. Moreover, the evaluation factor can be further reduced by changing structural parameters, such as using a larger number of periods. Simultaneously, the one-dimensional photonic crystal cascaded slit waveguide also exhibits superior optical bandwidth compared to two-dimensional photonic crystal structures, along with lower transmission loss and better fabrication robustness.

[0061] This invention proposes a one-dimensional photonic crystal cascaded slit waveguide structure based on a coupled resonant cavity. Utilizing the slow light effect and the enhanced optical field within the slit, it strengthens the interaction between light and electro-optic materials while ensuring a large operating optical bandwidth. The structural parameters of the one-dimensional photonic crystal cascaded slit waveguide were optimized, and a FoM = 2.87 × 10⁻⁶ was obtained by considering various factors. -7It boasts a high-efficiency performance with an optical bandwidth of 4.7 nm. The one-dimensional photonic crystal cascaded slit waveguide can serve as one arm of the MZI structure to enhance phase modulation, greatly reducing the length of the device. Combined with the advantages of electro-optic polymers, such as short response time and large electro-optic coefficient, it is expected to realize a small-size, low-power, and high-bandwidth electro-optic modulator.

[0062] In the structure proposed in this invention, the slit can also be filled with high electro-optic coefficient materials such as organic polymers, lithium niobate, and gallium arsenide to enhance the performance of optical devices. In the above description, electro-optic polymers were used as an example to demonstrate the potential of this invention to improve the modulation efficiency and bandwidth performance of electro-optic modulators. Besides electro-optic modulators, this invention can also be applied to other high-performance silicon heterogeneous integrated photonic devices, such as photoacoustic devices and all-optical switches; moreover, this invention also provides significant improvements for on-chip sensing such as electromagnetic field sensors and photocatalytic detection.

[0063] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A one-dimensional photonic crystal cascaded slit waveguide for silicon heterointegration, characterized in that, include: A single-crystal silicon layer, which constitutes the body of the slit waveguide; A slit, the slit being disposed on the monocrystalline silicon layer; The defect portion is formed by uniformly introducing a π phase shift. The defect portion is periodically arranged in a one-dimensional photonic crystal slit waveguide. The defect portion constitutes the resonant cavity of the one-dimensional photonic crystal cascaded slit waveguide, thereby forming a cascaded resonant unit of the one-dimensional photonic crystal cascaded slit waveguide. Each resonant unit consists of a one-dimensional photonic crystal slit waveguide with a period of 2NOP and a π phase shift. The defect length is half a period.

2. The one-dimensional photonic crystal cascaded slit waveguide for silicon heterogeneous integration as described in claim 1, characterized in that: The slit is filled with an electro-optic organic polymer.

3. The one-dimensional photonic crystal cascaded slit waveguide for silicon heterogeneous integration as described in claim 1, characterized in that: The slit waveguide includes a ridge waveguide with a height of 220 nm.

4. The one-dimensional photonic crystal cascaded slit waveguide for silicon heterogeneous integration as described in any one of claims 1-3, characterized in that: The slit waveguide includes silicon rails and silicon teeth.

5. The one-dimensional photonic crystal cascaded slit waveguide for silicon heterogeneous integration as described in any one of claims 1-3, characterized in that: The duty cycle of the resonant unit is 50%.

6. The one-dimensional photonic crystal cascaded slit waveguide for silicon heterogeneous integration as described in claim 2, characterized in that: The evaluation factor for the impact of waveguide optical structure on modulation performance is defined as follows: The change in effective refractive index in a slit waveguide structure is expressed as: Where Vπ represents the phase shift voltage, L represents the modulator length, λ represents the preset parameters, Ws represents the slit width, and r 33 n is the electro-optic coefficient of the electro-optic organic polymer. EO It is the effective index of electro-optic organic polymers without electro-optic effects, U is the bias voltage applied across the slit, and Γ is the effective index of electro-optic organic polymers without electro-optic effects. slot,y It is the field interaction factor of the TE0 mode.

7. The one-dimensional photonic crystal cascaded slit waveguide for silicon heterogeneous integration as described in claim 6, characterized in that: Γ slot,y Calculated using formula (3): ε is the relative permittivity of the material and the integration region, n g It is the group refractive index of the modes, Γ OCF G is the light field energy confinement factor in the slit region. n It is a time factor.

8. The one-dimensional photonic crystal cascaded slit waveguide for silicon heterogeneous integration as described in claim 7, characterized in that: The trade-off between optical bandwidth and group refractive index is described by the time delay-bandwidth product: Where, Δt=n g L / c represents the delay after the optical transmission length equals the modulator length L, f = w / 2π, Δf is the bandwidth centered at the bandwidth f, and Δn eff It represents the change in effective refractive index corresponding to the normalized bandwidth Δf / f.

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