Electro-optical modulator and optical device

Abstract

The present disclosure belongs to the technical field of optical communications. Provided are an electro-optical modulator and an optical device. The electro-optical modulator comprises a light source and a modulation structure. The modulation structure is located on an emergent light path of the light source; and the modulation structure comprises a modulation layer, a first electrode, a second electrode and an electric-field forming layer, wherein the first electrode, the second electrode and the electric-field forming layer are used for generating an electric field on the modulation layer so as to change the carrier concentration of the modulation layer. By means of the present disclosure, the electro-optical modulator uses the modulation structure to modulate, into pulsed light, continuous light emitted by the light source, so that the modulation bandwidth of the electro-optical modulator is not affected by parameters of the light source itself, and the modulation bandwidth of the electro-optical modulator can thus be improved.

Description

Electro-optic modulators and optical devices

[0001] This disclosure claims priority to Chinese Patent Application No. 202411204232.9, filed on August 29, 2024, entitled “Electro-optic Modulator and Optical Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of optical communication technology, and in particular to an electro-optic modulator and an optical device. Background Technology

[0003] Fiber optic connections are superior to cable connections in terms of transmission principles, interference resistance, transmission distance, and transmission quality. Therefore, most interconnections between communication devices in data centers use optical interconnects (OI). For example, communication devices may have optical modules inserted into their optical interfaces for connecting fiber optic cables, or the communication devices may integrate optical modules for connecting fiber optic cables.

[0004] Most current optical modules use surface emitting lasers (SELs) as their light source, such as vertical cavity surface emitting lasers (VCSELs) and photonic crystal surface emitting lasers (PCSELs). A surface emitting laser is a laser whose laser emission direction is perpendicular to the substrate surface.

[0005] With the rapid development of technologies such as cloud computing, ultra-high-definition video, and artificial intelligence, optical modules are facing the challenge of large bandwidth. The larger the bandwidth of the optical module, the larger the modulation bandwidth required for the surface-emitting laser. However, the modulation bandwidth obtained by the surface-emitting laser through direct modulation has reached its upper limit. Those skilled in the art urgently need to find other modulation methods for surface-emitting lasers. Summary of the Invention

[0006] This disclosure provides an electro-optic modulator and an optical device. The electro-optic modulator, when applied in laser applications, can improve the modulation bandwidth of the laser.

[0007] In a first aspect, an electro-optic modulator is provided, the electro-optic modulator including a light source and a modulation structure, the modulation structure being located in the outgoing light path of the light source;

[0008] The modulation structure includes a modulation layer, a first electrode, a second electrode, and an electric field forming layer. The first electrode, the second electrode, and the electric field forming layer are used to generate an electric field on the modulation layer to change the carrier concentration of the modulation layer.

[0009] In the scheme disclosed herein, the electro-optic modulator uses a modulation structure to modulate continuous light emitted from a light source into pulsed light. This allows the modulation bandwidth of the electro-optic modulator to be unaffected by the parameters of the light source itself, thus improving the modulation bandwidth. For example, if a surface-emitting laser is used as the light source, the modulation bandwidth of the electro-optic modulator is unaffected by the relaxation oscillation frequency, parasitic resistance, and parasitic capacitance of the surface-emitting laser, thereby improving the modulation bandwidth of the surface-emitting laser. The modulation structure includes a modulation layer. Applying a voltage to the modulation layer generates an electric field within it, increasing the carrier concentration and changing the refractive index of the modulation layer. This affects the optical properties of the modulation layer, converting the continuous light emitted by the surface-emitting laser into pulsed light, achieving electro-optic modulation. Furthermore, the modulation bandwidth can be improved by changing the characteristics of the modulation structure. For example, the modulation layer can use a TCO with a near-zero dielectric constant effect, or multiple electric fields can be formed within the modulation layer. These characteristics are all beneficial for improving the modulation bandwidth of the electro-optic modulator.

[0010] In one possible implementation, the modulation layer is located in the outgoing light path of the light source;

[0011] The modulation layer has a first electrode arranged on a first side close to the light source and a second electrode arranged on a second side away from the light source. The electric field forming layer is arranged between the first electrode and the second electrode.

[0012] The first side and the second side of the modulation layer are two opposite sides of the modulation layer in the transmission direction of the light source.

[0013] In the scheme disclosed herein, the modulation layer is located in the outgoing light path of the light source. When continuous light passes through the modulation layer, the light absorption rate of the modulation layer increases due to the increased carrier concentration within the modulation layer, thereby absorbing most of the light. Thus, during modulation, the modulation structure outputs weak light or even no light output, and the modulation stops. The modulation structure then outputs continuous light, thereby achieving electro-optic modulation.

[0014] In one possible implementation, there are multiple first electrodes, and the first electrodes are arranged on the first side of the modulation layer and in the modulation layer between the first and second sides of the modulation layer, and the electric field forming layer is arranged between the second electrode and the first electrode closest to the second electrode.

[0015] In the scheme shown in this disclosure, when a modulation voltage is applied to all the first electrodes at the same time, an electric field can be formed between each first electrode and the second electrode. Multiple electric fields are formed in the modulation layer, which rapidly increases the carrier concentration in the modulation layer, reduces the electro-optic modulation delay, and thus improves the modulation bandwidth.

[0016] In one possible implementation, there are multiple first electrodes, multiple second electrodes, and multiple electric field forming layers;

[0017] The first electrode and the second electrode are alternately arranged on the first side of the modulation layer, in the modulation layer, and on the second side of the modulation layer, and the electric field forming layer is arranged between the first electrode and the second electrode that are adjacent in position.

[0018] In the scheme disclosed herein, when a modulation voltage is applied to all the first electrodes simultaneously, an electric field can be formed between adjacent first and second electrodes, and multiple electric fields are formed in the modulation layer, which rapidly increases the carrier concentration in the modulation layer, reduces the electro-optic modulation delay, and thus improves the modulation bandwidth. Moreover, the scheme disclosed herein can achieve an improvement in modulation bandwidth even when the modulation layer is relatively thin.

[0019] In one possible implementation, the light source is a surface-emitting laser, and the modulation structure is located on the light-emitting surface of the surface-emitting laser, or the modulation structure is located above the light-emitting surface of the surface-emitting laser.

[0020] In the scheme shown in this disclosure, the modulation structure is applied to a surface-emitting laser, and the low cost of the surface-emitting laser enables a low-cost, large modulation bandwidth optical communication pulse laser source.

[0021] In one possible implementation, the modulation structure is located on the light-emitting surface of the light source, and the modulation layer is located on the light-emitting path of the light source, with both the first electrode and the second electrode offset from the light-emitting path of the light source.

[0022] In the scheme shown in this disclosure, the continuous light emitted by the light source is modulated into pulsed light by the modulation layer as it passes through the modulation layer.

[0023] In one possible implementation, both the first electrode and the second electrode are annular electrodes, and the outgoing light path of the light source is located within the annular space of the first electrode and the second electrode.

[0024] In the scheme shown in this disclosure, both the first electrode and the second electrode are ring electrodes, so that the electric field in the modulation layer is distributed around the circumference of the continuous beam, which can reduce electro-optic delay and increase modulation bandwidth.

[0025] In one possible implementation, the modulation structure is located above the light-emitting surface of the light source, and there is a distance H between the modulation structure and the light-emitting surface of the light source;

[0026] The modulation layer is located in the outgoing light path of the light source, and the second electrode on the second side of the modulation layer is located in the outgoing light path of the light source. The electrode of the second electrode on the second side of the modulation layer facing downward from the light source is offset from the outgoing light path of the light source.

[0027] The modulation structure further includes a grating layer, which is located below the second electrode on the second side of the modulation layer.

[0028] In the scheme shown in this disclosure, the continuous light emitted by the light source first passes through the modulation layer, is reflected by the second electrode, and then passes through the modulation layer again. This can extend the electro-optic modulation path and increase the extinction ratio of the pulse light. The greater the extinction ratio of the pulse light, the better the electro-optic modulation effect of the electro-optic modulator.

[0029] In one possible implementation, the modulation layer has a modulation region positioned opposite to the outgoing light path of the light source, and the first electrode extends into the modulation region.

[0030] In the scheme disclosed herein, continuous light is modulated within the modulation region of the corresponding laser beam, which can reduce electro-optic delay and increase modulation bandwidth.

[0031] In one possible implementation, the modulation structure further includes an optical waveguide located on the light-emitting surface of the light source and in the light-emitting path of the light source;

[0032] The modulation layer and the electric field forming layer are stacked on the surface of the optical waveguide perpendicular to the transmission direction.

[0033] In the scheme disclosed herein, a modulation layer and an electric field forming layer are superimposed on the surface of the optical waveguide perpendicular to the transmission direction. For example, the modulation layer is located on the surface of the optical waveguide, and the electric field forming layer is located on the surface of the modulation layer. The first electrode and the second electrode are used to generate electric fields on opposite sides of the modulation layer, increasing the carrier concentration of the modulation layer and changing the refractive index of the modulation layer. The change in the refractive index of the modulation layer will change the transmission loss of light in the optical waveguide, for example, increasing the transmission loss of light in the optical waveguide. Therefore, during modulation, the optical waveguide outputs relatively weak light, or even no light output; when modulation stops, the optical waveguide outputs continuous light, thereby realizing the output of pulsed light from the optical waveguide and achieving electro-optic modulation.

[0034] In another approach, the electric field forming layer can be located on the surface of the optical waveguide, while the modulation layer is located on the surface of the electric field forming layer.

[0035] In one possible implementation, the optical waveguide and the second electrode are both located on the light-emitting surface of the light source, and the optical waveguide and the second electrode are connected, with the optical waveguide perpendicular to the light path emitted from the light source;

[0036] The modulation layer, the first electrode, and the electric field forming layer are superimposed and circumferentially cover the outer surface of the optical waveguide, with the first electrode located on the outermost layer.

[0037] In the scheme shown in this disclosure, the modulation layer covers the outer side of the optical waveguide in the circumferential direction. The modulation layer generates an electric field around the optical waveguide in the circumferential direction, which greatly increases the carrier concentration. In electro-optic modulation, the carrier concentration increases rapidly and the electro-optic response is fast, which is beneficial to improving the modulation bandwidth.

[0038] In one possible implementation, the modulation structure further includes a reflector located on the light-emitting surface of the light source and in the light-emitting path of the light source, and the optical waveguide horizontally located on the light-emitting surface of the light source and in the light-reflecting path of the reflector.

[0039] The modulation layer, the first electrode, and the electric field forming layer are stacked on the surface of the optical waveguide opposite to the light source, with the first electrode located on the outermost side and the second electrode located on the surface of the optical waveguide opposite to the light source.

[0040] In one possible implementation, the modulation layer is made of transparent conductive oxide (TCO).

[0041] In the scheme shown in this disclosure, the TCO has a high electro-optic modulation effect, and utilizing this effect of the TCO is beneficial to improving the modulation bandwidth of the electro-optic modulator.

[0042] In one possible implementation, the electric field forming layer is made of silicon oxide, aluminum oxide, or hafnium dioxide.

[0043] In a second aspect, an optical device is provided, the optical device comprising the electro-optic modulator described in the first aspect. Attached Figure Description

[0044] Figure 1 is a schematic diagram of the structure of an electro-optic modulator provided in an exemplary embodiment of the present disclosure;

[0045] Figure 2 is a schematic diagram of the structure of an electro-optic modulator provided in an exemplary embodiment of the present disclosure;

[0046] Figure 3 is a schematic diagram of the structure of an electro-optic modulator provided in an exemplary embodiment of the present disclosure;

[0047] Figure 4 is a screenshot of Figure 3 at point AA;

[0048] Figure 5 is a schematic diagram of the modulation region of a modulation layer provided in an exemplary embodiment of this disclosure;

[0049] Figure 6 is a cross-sectional schematic diagram of an electro-optic modulator provided in an exemplary embodiment of the present disclosure;

[0050] Figure 7 is a cross-sectional schematic diagram of an electro-optic modulator provided in an exemplary embodiment of the present disclosure;

[0051] Figure 8 is a schematic diagram of the structure of an electro-optic modulator provided in an exemplary embodiment of the present disclosure;

[0052] Figure 9 is a cross-sectional schematic diagram of a modulation structure provided in an exemplary embodiment of this disclosure;

[0053] Figure 10 is a schematic diagram of a modulation structure provided in an exemplary embodiment of the present disclosure;

[0054] Figure 11 is a schematic diagram of a modulation structure provided in an exemplary embodiment of the present disclosure;

[0055] Figure 12 is a partial cross-sectional schematic diagram of an electro-optic modulator provided in an exemplary embodiment of the present disclosure;

[0056] Figure 13 is a schematic diagram of the structure of an electro-optic modulator provided in an exemplary embodiment of the present disclosure.

[0057] Explanation of reference numerals in the attached figures: 1. Light source; 2. Modulation structure; 21. Modulation layer; 211. Modulation region; 212. Annular groove; 22. First electrode; 23. Second electrode; 24. Electric field forming layer; 25. Grating layer; 26. Optical waveguide; 27. Mirror. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0059] This embodiment relates to an electro-optic modulator, a device used to modulate electrical signals into optical signals. If its internal light source is a laser, the electro-optic modulator can also be called a modulated laser. This embodiment specifically relates to the modulation method of the electro-optic modulator, and it is not significantly related to whether the light source inside the electro-optic modulator is a laser light source or a diode light source. Therefore, for ease of explanation, this embodiment uses a laser light source and the electro-optic modulator as a modulated laser for example.

[0060] In current data centers, most communication devices are interconnected via optical interconnection. This means that communication devices are linked through optical fibers, while the signals within the devices are electrical signals. Therefore, communication devices have optical module interfaces (also called optical cage interfaces). The electrical connectors of the optical modules plug into these interfaces, and the fiber optic connectors plug into the optical interfaces of the modules. The optical modules perform photoelectric conversion, thus enabling optical interconnection between communication devices through pluggable optical modules. Alternatively, communication devices can integrate optical modules; that is, the communication device's panel has optical interfaces, and the fiber optic connectors directly plug into these interfaces, achieving optical interconnection between the devices.

[0061] Whether the optical module is independent of the communication device or integrated into the communication device, as the operating speed of the communication device increases, the bandwidth of the optical module also needs to be increased, and the modulation bandwidth of the laser inside the optical module, which serves as the light source, also needs to be increased.

[0062] The modulation bandwidth of a laser is the highest output or loaded signal rate (for digital signals), or the maximum bandwidth of the output (or loaded) analog signal. The larger the modulation bandwidth of a laser, the more information it carries per unit time.

[0063] Currently, optical modules used in short-distance transmission scenarios in data centers mostly employ surface-emitting lasers as their light source, such as vertical cavity surface emitting lasers (VCSELs) or photonic crystal surface emitting lasers (PCSELs).

[0064] Among them, the photoelectric modulation method of surface-emitting lasers mostly adopts direct modulation. Direct modulation means that the driving current of the surface-emitting laser is directly modulated by an electrical signal, causing the surface-emitting laser to emit a modulated optical signal, which is pulsed light. Direct modulation can also be understood as generating a pulsed driving current based on the electrical signal to be modulated, and using the pulsed driving current to drive the surface-emitting laser to emit light, causing the surface-emitting laser to emit pulsed light. For example, if the driving current is relatively large at a certain moment, the intensity of the driven laser light will be large, and if the driving current is relatively small at a certain moment, the intensity of the driven laser light will be weak, thus obtaining pulsed light.

[0065] In the modulation of surface-emitting lasers using direct modulation, the modulation bandwidth is related to the relaxation oscillation frequency, parasitic resistance, and parasitic capacitance of the surface-emitting laser. The modulation bandwidth can be improved by optimizing these parameters of the surface-emitting laser. However, the parameters of surface-emitting lasers have been optimized to their limits, and the modulation bandwidth of direct modulation of surface-emitting lasers has almost reached its upper limit (around 30 GHz).

[0066] In contrast to surface-emitting lasers, edge-emitting lasers (EELs) have a very high modulation bandwidth, such as over 50 GHz. However, edge-emitting lasers are more expensive. Since the demand for optical modules in optical interconnects in data centers is very high, the application of edge-emitting lasers with high modulation bandwidth in data centers is more costly.

[0067] Therefore, for low-cost surface-emitting lasers, it is necessary to find other modulation methods to further improve the modulation bandwidth of surface-emitting lasers in order to meet the low-cost and high-bandwidth requirements of optical modules.

[0068] This embodiment provides an electro-optic modulator whose photoelectric modulation method is no longer direct modulation, but external modulation. External modulation uses a modulation structure to modulate the continuous light emitted by a surface-emitting laser into pulsed light. This modulation method is not limited by the parameters of the surface-emitting laser itself, such as the relaxation oscillation frequency, parasitic resistance, and parasitic capacitance of the surface-emitting laser, thus further improving the modulation bandwidth of the surface-emitting laser.

[0069] In this embodiment, the modulation structure 2 is used to convert the continuous light emitted by the light source 1 into pulsed light, thereby achieving electro-optic modulation. Specifically, an electric field is generated on the modulation layer 21 of the modulation structure 2, increasing the carrier concentration inside the modulation layer 21. The light source 1 can be a surface-emitting laser, such as a VCSEL or PCSEL.

[0070] It should be noted that since the electro-optic modulator achieves optical signal modulation through modulation structure 2, the driving current of the laser emitting surface can be constant, and it does not need to be a pulsed driving current.

[0071] The carrier concentration of a material changes its dielectric constant, and further based on... Here, Δn represents the change in refractive index, Δε represents the change in dielectric constant, and ε represents the dielectric constant. Therefore, a change in the carrier concentration of modulation layer 21 will cause a change in the refractive index of modulation layer 21. This change in the refractive index of modulation layer 21 will affect its optical properties.

[0072] In one embodiment, continuous light emitted from the light source undergoes electro-optic modulation as it passes through modulation layer 21. For example, an increase in carrier concentration within modulation layer 21 leads to a greater absorptivity. Consequently, the increased absorptivity of modulation layer 21 weakens the light intensity as it passes through, or even eliminates light output. Therefore, without electro-optic modulation, the intensity of continuous light emitted from light source 1 passing through modulation layer 21 remains essentially constant. However, with electro-optic modulation, the intensity of continuous light emitted from light source 1 passing through modulation layer 21 weakens, or even eliminates light output. This allows the electro-optic modulator to generate pulsed light after modulation by modulation structure 2.

[0073] Another approach is that changing the refractive index of the modulation layer 21 affects the propagation of light in the optical waveguide. For example, if the modulation layer 21 is located on the surface of the optical waveguide, or if the modulation layer 21 covers the optical waveguide, then changing the refractive index of the modulation layer 21 will increase the light transmission loss in the optical waveguide. Therefore, without electro-optic modulation, the continuous light emitted by the light source 1 propagates normally in the optical waveguide. However, with electro-optic modulation, the continuous light emitted by the light source 1 experiences increased loss in the optical waveguide, resulting in weaker light intensity or even no light output from the optical waveguide. Consequently, the electro-optic modulator generates pulsed light after modulation by the modulation structure 2.

[0074] Still based on The modulation layer 21 can be made of a material with a dielectric constant near zero (ENZ). In this way, a small change in the dielectric constant of the modulation layer 21 can cause a large change in the refractive index of the modulation layer 21. Therefore, the modulation bandwidth of the electro-optic modulator can be improved based on the high-speed electro-optic modulation effect of the modulation layer 21.

[0075] Transparent conductive oxide (TCO) has a near-zero dielectric constant, so the modulation layer 21 can be made of TCO, specifically indium tin oxide (ITO). Furthermore, since the dielectric constant of TCO can approach zero in the near-infrared band, the electro-optic modulator can operate in the near-infrared band, for example, from 850 nm to 1550 nm.

[0076] The specific material of the modulation layer 21 can be, based on tin oxide (SnO), doped with one or more of antimony (Sb), fluorine (F), arsenic (As), niobium (Nb), and tantalum (Ta). Alternatively, based on zinc oxide (ZnO), doped with one or more of aluminum (Al), gallium (Ga), boron (B), indium (In), yttrium (Y), scandium (Sc), fluorine (F), vanadium (V), silicon (Si), germanium (Ge), titanium (Ti), zirconium (Zr), hafnium (Hf), magnesium (Mg), arsenic (As), and hydrogen (H). Alternatively, based on indium tin oxide (In₂Sn₃), doped with one or more of molybdenum (Mo), tantalum (Ta), tungsten (W), zirconium (Zr), fluorine (F), germanium (Ge), niobium (Nb), hafnium (Hf), and magnesium (Mg). Alternatively, based on cadmium oxide (CdO), doped with indium (In) and / or tin (Sn). Alternatively, based on gallium indium oxide (GaInO₃), doped with tin (Sn) and / or germanium (Ge). Alternatively, based on cadmium antimony oxide (CdSb₂O₃), doped with yttrium (Y).

[0077] The thickness of the modulation layer 21 can be greater than or equal to 10 nanometers and less than or equal to 10 micrometers. The specific thickness of the modulation layer 21 can be determined according to the operating wavelength of the electro-optic modulator.

[0078] Based on the above, referring to FIG1, the electro-optic modulator includes a light source 1 that emits continuous light and a modulation structure 2 for modulating the continuous light into pulsed light. The modulation structure 2 includes a modulation layer 21 and at least two electrodes. The at least two electrodes generate an electric field on the modulation layer 21 to increase the carrier concentration of the modulation layer 21, thereby changing the absorptivity or refractive index of the modulation layer 21.

[0079] In this configuration, at least two electrodes are metallic electrodes used to generate a voltage difference in electro-optic modulation. Because the two electrodes have different polarities in application, for example, one may serve as a driving electrode applying voltage and the other as a grounding electrode; or, for example, one may serve as a positive electrode applying a positive voltage and the other as a negative electrode applying a negative voltage. For ease of explanation, the driving electrode will be referred to as the first electrode 22, and the grounding electrode as the second electrode 23.

[0080] Since the modulation layer 21 is conductive, the first electrode 22 and the second electrode 23 are directly arranged on opposite sides of the modulation layer 21, which will result in a current path being formed on these two sides of the modulation layer 21 without generating an electric field. Therefore, in order to form an electric field, an electric field forming layer 24 needs to be arranged between the two electrodes. The electric field forming layer 24 is used to form electrical isolation between the two electrodes. For example, it can be an insulating layer or a doped semiconductor layer, as described later.

[0081] The specific implementation structures of the two schemes mentioned above are described below.

[0082] (a) A scheme in which continuous light emitted from a light source passes through a modulation layer 21, and the modulation layer 21 modulates the continuous light into pulsed light.

[0083] Figure 1 shows a schematic diagram of an electro-optic modulator. Referring to Figure 1, the electro-optic modulator includes a light source 1 and a modulation structure 2. The modulation structure 2 includes a modulation layer 21, a first electrode 22, and a second electrode 23. The modulation layer 21 is located on the outgoing light path of the light source. The first electrode 22 is arranged on the first side of the modulation layer 21, and the second electrode 23 is arranged on the second side. The first side and the second side of the modulation layer 21 are two opposite sides of the modulation layer 21 on the outgoing light path of the light source 1.

[0084] In one example, the modulation layer 21 is conductive, and the voltage difference generated by the first electrode 22 and the second electrode 23 can generate a voltage difference between the first side and the second side of the modulation layer 21 that are positioned opposite each other, thereby generating an electric field between the first side and the second side of the modulation layer 21 that are positioned opposite each other.

[0085] As described above, the modulation layer 21 is conductive. The voltage difference between the first electrode 22 and the second electrode 23 will cause the modulation layer 21 to form a conductive path without generating an electric field. Therefore, in order to generate an electric field on the modulation layer 21, referring to FIG1, the modulation structure 2 further includes an electric field forming layer 24. The electric field forming layer 24 is arranged between the first electrode 22 and the second electrode 23. The electric field forming layer 24 is used to generate an electric field on the modulation layer 21 when there is a voltage difference between the first electrode 22 and the second electrode 23.

[0086] Specifically, the electric field forming layer 24 can be an insulating layer, and its material can be silicon oxide (SiO2), hafnium dioxide (HfO2), or aluminum oxide (Al2O3). When the electric field forming layer 24 is an insulating layer, its thickness can be greater than or equal to 5 nanometers and less than or equal to 50 micrometers.

[0087] In another example, if the modulation layer 21 is an N-type semiconductor, then the electric field forming layer 24 can be a P-type semiconductor; conversely, if the modulation layer 21 is a P-type semiconductor, then the electric field forming layer 24 can be an N-type semiconductor. The P-type and N-type semiconductors form a PN junction at the interface, generating an internal electric field. For example, if the modulation layer 21 is the TCO described above, the TCO is an N-type semiconductor, and the electric field forming layer 24 can be a P-type semiconductor.

[0088] When a voltage is applied to the first electrode 22, an electric field is generated between the first electrode 22 and the second electrode 23 under the action of the electric field forming layer 24. Since the first electrode 22 is located on the first side of the modulation layer 21 and the second electrode 23 is located on the second side of the modulation layer 21, an electric field is generated between the first and second sides of the modulation layer 21, causing positively charged carriers to accumulate on the first side of the modulation layer 21 and negatively charged carriers to accumulate on the second side, thereby increasing the carrier concentration of the modulation layer 21.

[0089] In the scheme where continuous light emitted from the light source passes through the modulation layer 21 and the modulation layer 21 modulates the continuous light into pulsed light, based on the relationship between the modulation structure 2 and the light source 1, there are at least two other schemes: The first scheme can be, as shown in Figure 1, where the modulation structure 2 is directly located on the light-emitting surface of the surface-emitting laser, and the modulated pulsed light is transmitted through the modulation structure 2; the second scheme can be, as shown in Figure 8, where the modulation structure 2 is located above the surface-emitting laser, and the modulated pulsed light is reflected from the modulation structure 2.

[0090] Regardless of the first or second scheme, the first and second sides of the modulation layer 21 are opposite sides of the modulation layer 21 along the light path emitted from the light source 1. For example, as shown in Figure 1, the first side of the modulation layer 21 is the lower side of the modulation layer 21 closer to the light source 1, and the second side is the upper side of the modulation layer 21 farther away from the light source 1.

[0091] The first option will be introduced first, followed by the second option.

[0092] As shown in Figures 1 and 2, the light source 1 is a surface-emitting laser, and the modulation structure 2 is located on the light-emitting surface of the surface-emitting laser. Furthermore, the modulation layer 21 is located in the light path of the light source 1. The first electrode 22 and the second electrode 23 are both offset from the light path of the light source 1; that is, neither the first electrode 22 nor the second electrode 23 is in the light path of the light source 1. Thus, the continuous light emitted by the light source 1 is incident on the modulation layer 21, propagates within the modulation layer 21, and then exits from the modulation layer 21.

[0093] In one example, as shown in Figure 2, the modulation layer 21 is located on the light-emitting surface of the surface-emitting laser and covers the light path of the surface-emitting laser. The electric field forming layer 24 is located on the upper surface of the surface-emitting laser opposite to the modulation layer 21. Moreover, the electric field forming layer 24 is transparent, for example, it can transmit the light beam in the operating band of the electro-optic modulator.

[0094] Referring again to Figure 2, a first electrode 22 is arranged on the first side of the modulation layer 21. For example, the first electrode 22 is located on the light-emitting surface of the surface-emitting laser. A second electrode 23 is arranged on the second side of the modulation layer 21. For example, the second electrode 23 is located on the upper surface of the electric field forming layer 24 opposite to the modulation layer 21. Neither the first electrode 22 nor the second electrode 23 is in the output light path of the surface-emitting laser.

[0095] In another example, the electric field forming layer 24 can be located on the emitting surface of the surface-emitting laser, and the modulation layer 21 can be located on the upper surface of the surface-emitting laser opposite to the electric field forming layer 24. In this arrangement, a first electrode 22 is arranged on the first side of the modulation layer 21, for example, the first electrode 22 is located on the emitting surface of the surface-emitting laser. A second electrode 23 is arranged on the second side of the modulation layer 21, for example, the second electrode 23 is arranged on the upper surface of the modulation layer 21 opposite to the electric field forming layer 24. Neither the first electrode 22 nor the second electrode 23 is in the output light path of the surface-emitting laser.

[0096] In this embodiment, the arrangement of the modulation layer 21, the electric field forming layer 24, the first electrode 22, and the second electrode 23 is not limited, as long as the modulation layer 21 is located in the output light path of the light source and can generate an electric field in the thickness direction. For ease of explanation, Figure 1 shows an example where the modulation layer 21 is located on the light-emitting surface of the surface-emitting laser, and the electric field forming layer 24 is located on the upper surface of the modulation layer 21. The electric field forming layer 24 and the modulation layer 21 have the same shape and size and are stacked on the light-emitting surface of the surface-emitting laser.

[0097] In one example, in order to ensure that neither the first electrode 22 nor the second electrode 23 covers the optical path, as shown in Figures 3 and 4, the first electrode 22 and the second electrode 23 can both be ring electrodes. The space inside the ring of the first electrode 22 and the second electrode 23 is opposite to the position of the output optical path of the surface-emitting laser. That is, the laser emitted by the surface-emitting laser is transmitted in the space inside the ring of the first electrode 22 and the second electrode 23.

[0098] In general, semiconductor lasers are packaged inside TO tubes. Therefore, as shown in Figure 3, the surface-emitting laser has a tubular structure. Thus, the modulation structure 2 located on the light-emitting surface of the surface-emitting laser is also schematically shown in a disk shape.

[0099] In one example, as shown in Figure 4, the laser beam emitted by the surface-emitting laser only propagates along the outgoing optical path. Therefore, the modulation layer 21 can modulate the laser beam in the region through which it passes. Accordingly, as shown in Figure 4, the modulation layer 21 has a modulation region 211, which is positioned opposite to the outgoing optical path of the surface-emitting laser. For example, the modulation region 211 is located on the outgoing optical path of the surface-emitting laser. The first electrode 22 extends into the modulation region 211, and the second electrode 23 can also extend into the modulation region 211, causing charge carriers to accumulate on the first and second sides of the modulation region 211. For example, referring to Figure 4, an electric field is formed between the first electrode 22 and the second electrode 23, and in the modulation region 211. A large number of positively charged charge carriers accumulate on the lower surface of the modulation region 211 (the surface facing the light source 1), and a large number of negatively charged charge carriers accumulate on the upper surface of the modulation region 211 (i.e., the surface facing the electric field forming layer 24), causing an increase in the absorption rate within the modulation region 211. As a result, a large amount of laser light is absorbed as it passes through the modulation region 211.

[0100] As shown in Figure 4, the cross-sectional shape of the modulation region 211 is circular, and its diameter can be greater than or equal to 0.1 micrometers and less than or equal to 20 micrometers.

[0101] In one example, the modulation region 211 can be formed by ion implantation. For instance, ion implantation is performed within the modulation region 211 of the modulation layer 21, making the conductivity of the modulation region 211 higher than that of other regions of the modulation layer 21 (i.e., the non-modulation region). Furthermore, the modulation layer 21 has conductivity in the modulation region 211 and insulation in the non-modulation region. Then, under the voltage difference between the first electrode 22 and the second electrode 23, charge carriers accumulate in the modulation region 211, thereby purposefully increasing the charge carrier concentration in the modulation region 211. This is beneficial for reducing RC delay and increasing the modulation bandwidth of the electro-optic modulator. The smaller the RC delay, the faster the resistance R of the modulation layer 21 controls the charging and discharging speed of the capacitor C, and the larger the modulation bandwidth.

[0102] In another example, the modulation region 211 can also be formed by etching a through-groove through the thickness of the modulation layer 21 on the modulation layer 21. For example, as shown in FIG5, an annular groove 212 through the thickness of the modulation layer 21 is etched on the modulation layer 21. The area inside the annular groove 212 serves as the modulation region 211, while the area outside the annular groove 212 serves as the non-modulation region. In this embodiment, the method of forming the modulation region 211 is not limited.

[0103] In one example, the modulation region 211 is formed by ion implantation. The depth of ion implantation is affected by the thickness of the modulation layer 21. For example, the greater the thickness of the modulation layer 21, the shallower the ion implantation depth and the more difficult the ion implantation. The modulation region 211 is also formed by etching annular grooves 212. The etching depth is also affected by the thickness of the modulation layer 21. For example, the greater the thickness of the modulation layer 21, the shallower the etching depth and the more difficult the etching.

[0104] Therefore, the modulation layer 21 can be deposited on the surface of the surface-emitting laser in multiple depositions. For example, after each deposition of a modulation layer 21, an ion implantation is performed to form a modulation region 211. Alternatively, after each deposition of a modulation layer 21, an etching is performed to form a modulation region 211.

[0105] It should be noted that in the scheme of multiple deposition of modulation layer 21, the material of each deposition of modulation layer 21 can be the same as the material of the previous deposition. For example, the material of the first deposition of modulation layer 21 can be the same as the material of the second deposition. Alternatively, the material of each deposition of modulation layer 21 can be different from the material of the previous deposition. This embodiment does not specifically limit whether the material of each deposition of modulation layer 21 is the same as the material of the previous deposition.

[0106] In one example, the modulation layer 21 is arranged on the light-emitting surface of the surface-emitting laser by multiple depositions, which also helps to achieve multiple first electrodes 22, as well as multiple first electrodes 22, multiple second electrodes 23 and multiple electric field forming layers 24.

[0107] For example, there are multiple first electrodes 22, and one second electrode 23 and one electric field forming layer 24, as shown in FIG6. Not only are the first electrodes 22 arranged on the first side of the modulation layer 21, but at least one first electrode 22 is also arranged in the modulation layer 21 between the first and second sides. All of these multiple first electrodes 22 form an electric field between the second electrode 23. In order for all of them to form an electric field with the second electrode 23, an electric field forming layer 24 is arranged between the second electrode 23 and all the first electrodes 22. For example, referring to FIG6, an electric field forming layer 24 is arranged between the second electrode 23 and the first electrode 22 closest to the second electrode 23.

[0108] As shown in Figure 6, with three first electrodes 22 as an example, the first first electrode 22 is arranged on the lower surface of the light-emitting surface of the face-to-face laser emitting device of the modulation layer 21. A second and third first electrode 22 are arranged between the upper and lower surfaces of the modulation layer 21. Any two adjacent first electrodes 22 are spaced apart, and the third first electrode 22 is separated from the second electrode 23 by an electric field forming layer 24. Thus, an electric field can be formed between the first and second electrodes 22, between the second and third electrodes 22, and between the third and second electrodes 23.

[0109] For example, as shown in Figure 7, there are multiple first electrodes 22, multiple second electrodes 23, and multiple electric field forming layers 24. First electrodes 22 and second electrodes 23 are alternately arranged on the first side, in the middle, and on the second side of the modulation layer 21. Electric field forming layers 24 are arranged between adjacent first electrodes 22 and second electrodes 23, dividing the modulation layer 21 into multiple segments. In this way, an electric field can be formed between any two adjacent first electrodes 22 and second electrodes 23.

[0110] As shown in Figure 7, a first electrode 22 is arranged on the first side of the modulation layer 21, a first second electrode 23 is arranged in the modulation layer 21, a second first electrode 22 is arranged in the modulation layer 21, and a second second electrode 23 is arranged on the second side of the modulation layer 21. An electric field forming layer 24 is arranged between any two adjacent electrodes. For example, a first electric field forming layer 24 is arranged between the first first electrode 22 and the first second electrode 23, a second electric field forming layer 24 is arranged between the first second electrode 23 and the second first electrode 22, and a third electric field forming layer 24 is arranged between the second first electrode 22 and the second second electrode 23. Thus, an electric field is formed between the first first electrode 22 and the first second electrode 23, between the first second electrode 23 and the second first electrode 22, and between the second first electrode 22 and the second second electrode 23.

[0111] It should be noted that during modulation, the same or different voltages can be applied to multiple first electrodes 22 simultaneously. Applying voltage to multiple first electrodes 22 simultaneously can rapidly increase the carrier concentration in the modulation layer 21, thereby rapidly increasing the carrier concentration in the modulation region 211, reducing RC delay, and improving the modulation bandwidth.

[0112] It should be noted that in the scheme where the second electrode 23 is a ground electrode, the above-mentioned multiple second electrodes 23 share a common ground.

[0113] The modulation structure 2 includes a plurality of first electrodes 22, a plurality of second electrodes 23 and a plurality of electric field forming layers 24. Compared with the modulation structure 2 including a plurality of first electrodes 22, while the number of second electrodes 23 and electric field forming layers 24 is one, the former can achieve a larger modulation bandwidth with a smaller thickness in the modulation layer 21.

[0114] The above describes a scheme where the modulation structure 2 is directly located on the output surface of the surface-emitting laser, and the modulated pulsed light passes through the modulation structure 2. The following will introduce a scheme where the modulation structure 2 is located above the output surface of the surface-emitting laser, and the modulated pulsed light is reflected out from the modulation structure 2.

[0115] As shown in Figure 8, the modulation structure 2 is located above the light-emitting surface of the light source 1, and there is a distance H between the modulation structure 2 and the light-emitting surface of the light source 1. The modulation layer 21 is located in the light path of the light source 1, and the second electrode 23 arranged on the second side of the modulation layer 21 is also located in the light path of the light source 1. Other electrodes, such as the first electrode 22 arranged on the first side of the modulation layer 21, and the electrodes (first electrode 22 and / or second electrode 23) arranged in the modulation layer 21, are not in the light path of the light source 1. In this way, the laser emitted from the light source 1 can enter the modulation layer 21, pass through the modulation layer 21, and strike the second electrode 23 on the second side of the modulation layer 21, and be reflected by the second electrode 23.

[0116] The reason why there is a distance H between the modulation structure 2 and the light-emitting surface of the light source 1 is to allow the laser light hitting the uppermost second electrode 23 to be reflected.

[0117] In one example, there may be an air layer between the modulation structure 2 and the light-emitting surface of the light source 1. In another example, there may be any light-transmitting material between the modulation structure 2 and the light-emitting surface of the light source 1; for example, a light-transmitting glass layer may be arranged between the modulation structure 2 and the light-emitting surface of the light source 1.

[0118] In one example, since the laser emitted from the surface-emitting laser passes vertically through the modulation layer 21 and is incident vertically on the uppermost second electrode 23, it will also be reflected vertically by the uppermost second electrode 23. To avoid vertical reflection, the modulation structure 2 will also include a grating layer 25, which is used to enable the laser incident vertically on the uppermost second electrode 23 to be reflected at an angle.

[0119] Before introducing the specific structure of modulation structure 2, it should be noted that in the scheme shown in Figure 8, modulation layer 21 can also have modulation region 211. The characteristics of modulation region 211 can be referred to the above description and will not be repeated here. In the scheme shown in Figure 8, the number of first electrodes 22 can also be multiple, and the number of second electrodes 23 and electric field forming layer 24 is one each. In this scheme, the second electrode 23 covers the light path of the light source, while all the first electrodes 22 do not completely cover the light path of the light source, so that the laser emitted from the light source can pass through the first electrode 22 and modulation layer 21, hit the second electrode 23, and be reflected by the second electrode 23. For example, the first electrode 22 can be a ring electrode, and the laser emitted from the light source passes through the space inside the ring of the first electrode 22. In the scheme shown in Figure 8, there are multiple first electrodes 22, second electrodes 23, and electric field forming layers 24. In this scheme, it is only necessary to ensure that the uppermost second electrode 23 is located in the light path of the light source. Other electrodes, such as other first electrodes 22 and other second electrodes 23, do not completely cover the light path of the light source, so that the laser emitted from the light source can pass through the first electrode 22 and the modulation layer 21, hit the uppermost second electrode 23, and be reflected by the uppermost second electrode 23. For example, except for the uppermost second electrode 23, the other electrodes are all ring electrodes, and the space inside the ring is located in the light path of the light source.

[0120] In the following description of the specific structure of modulation structure 2, the example is a first electrode 22, a second electrode 23 and an electric field forming layer 24.

[0121] The specific structure of modulation structure 2 can be referred to Figures 9 to 11. Referring to Figure 9, the first electrode 22 is located on the lower surface of modulation layer 21 and is not in the output light path of the surface-emitting laser. Continuing to refer to Figure 9, the first electrode 22 can be a ring electrode, and the continuous light emitted by the light source 1 passes through the ring space of the first electrode 22.

[0122] Referring again to Figure 9, the second electrode 23 is located above the modulation layer 21 and covers the output light path of the laser emitter. The electric field forming layer 24 is located between the second electrode 23 and the modulation layer 21. The grating layer 25 is located between the modulation layer 21 and the electric field forming layer 24, and a portion of the modulation layer 21 extends into the slit of the grating layer 25. Alternatively, in Figure 9, the grating layer 25 can also be arranged between the electric field forming layer 24 and the second electrode 23.

[0123] Referring to Figure 10, the first electrode 22 is located on the lower surface of the modulation layer 21 facing the light-emitting surface of the light source 1, the electric field forming layer 24 is located on the upper surface of the modulation layer 21 facing away from the light-emitting surface of the light source 1, and the second electrode 23 is located on the upper surface of the electric field forming layer 24, and the second electrode 23 covers the light path emitted from the light source 1. Continuing to refer to Figure 10, multiple slits are etched on the first electrode 22 to form a grating layer.

[0124] In one example, in the process of etching a slit in the first electrode 22 in FIG10 to form a grating layer, the slit can extend to the modulation layer 21. Referring to FIG11, both the first electrode 22 and the modulation layer 21 have slits. Thus, the first electrode 22 and the modulation layer 21 together form a grating layer.

[0125] The above are several structural forms of modulation structure 2. This embodiment does not limit the specific structure of the reflective modulation structure 2. It satisfies that the second electrode 23 located at the top far from the light source 1 covers the output light path of the light source 1, the other electrodes do not cover the output light path of the light source 1, and a grating layer is arranged below the top second electrode 23 so that the laser emitted from the light source 1 can hit the top second electrode 23 and be reflected outward through the top second electrode 23.

[0126] (ii) In the transmission of continuous light emitted by the light source in the optical waveguide, the modulation layer 21 modulates the continuous light into pulse light.

[0127] In this scheme, the modulation structure 2 includes an optical waveguide 26, which is located on the light-emitting surface of the light source 1 and on the light-emitting path of the light source 1. For example, as shown in Figure 12, the optical waveguide 26 is directly on the light-emitting path of the light source 1. Or, as shown in Figure 13, the optical waveguide 26 is indirectly located on the light-emitting path of the light source 1.

[0128] The optical waveguide 26 can be made of silicon, making it a silicon waveguide. The thickness of the optical waveguide 26 is less than 10 micrometers to achieve an ultra-thin optical waveguide.

[0129] The modulation layer 21 and the electric field forming layer 24 are stacked on the surface of the optical waveguide 26 perpendicular to the transmission direction. For example, the modulation layer 21 and the electric field forming layer 24 cover the outside of the optical waveguide 26 so that when the refractive index of the modulation layer 21 changes, the transmission loss of light in the optical waveguide 26 increases.

[0130] This scheme includes at least two options: the first option, as shown in Figure 12, is that the optical waveguide 26 is perpendicular to the light-emitting surface of the light source 1 and is on the light-emitting path of the light source 1; the second option, as shown in Figure 13, is that the optical waveguide 26 is horizontally located on the light-emitting surface of the light source 1. The specific structures of the two options are described below.

[0131] Regardless of whether it is the first or the second scheme, the cross-sectional shape of the optical waveguide 26 can be circular or polygonal (such as rectangular). For ease of illustration, the first scheme is illustrated with a circle and the second scheme with a rectangle.

[0132] Referring to Figure 12, the optical waveguide 26 is perpendicularly located on the light-emitting surface of the light source 1 and covers the light path emitted from the light source 1. The modulation layer 21, the first electrode 22, and the electric field forming layer 24 are stacked and circumferentially covered on the outer surface of the optical waveguide 26. For example, the electric field forming layer 24, the modulation layer 21, and the first electrode 22 are sequentially covered on the outer surface of the optical waveguide 26 from the inside to the outside. Another example is that the modulation layer 21, the electric field forming layer 24, and the first electrode 22 are sequentially covered on the outer surface of the optical waveguide 26 from the inside to the outside.

[0133] The second electrode 23 is located on the light-emitting surface of the light source 1, and there is a connection between the second electrode 23 and the optical waveguide 26.

[0134] Thus, when a voltage is applied to the first electrode 22, the potential of the outer surface of the modulation layer 21 near the first electrode 22 is high, and the potential of the inner surface of the modulation layer 21 near the optical waveguide 26 is low. Under the electrical isolation of the electric field forming layer 24, an electric field is formed between the outer surface and the inner surface of the modulation layer 21. A large number of positively charged carriers accumulate on the outer surface of the modulation layer 21, and a large number of negatively charged carriers accumulate on the inner surface of the modulation layer 21.

[0135] In other examples, the second electrode 23 may also be wrapped around the optical waveguide 26. For example, in the embodiment shown in FIG12, the second electrode 23 may be wrapped between the optical waveguide 26 and the electric field forming layer 24. As another example, in an embodiment where the modulation layer 21, the electric field forming layer 24, and the first electrode 22 are sequentially wrapped around the outer surface of the optical waveguide 26 from the inside out, the second electrode 23 may be wrapped between the optical waveguide 26 and the modulation layer 21. Because the optical waveguide 26 is a silicon waveguide and has conductivity, as shown in FIG12, the second electrode 23 may be arranged on the light-emitting surface of the light source 1, and the second electrode 23 and the optical waveguide 26 may be connected through the surface of the light source 1. Here, the light source 1 is a semiconductor laser, and its surface is a stack of silicon material, which has conductivity.

[0136] In one example, since the continuous light is modulated during transmission in the optical waveguide 26, the electro-optic modulation effect is better if the refractive index of the modulation layer 21 changes along the transmission direction of the optical waveguide 26. Therefore, referring to Figure 12, the heights of the modulation layer 21 and the electric field forming layer 24 are the same as the height of the optical waveguide 26, while the height of the first electrode 22 is slightly less than the height of the optical waveguide 26. This is because if the first electrode 22 is at the same height as the optical waveguide 26, then, referring to Figure 12, the first electrode 22 and the second electrode 23 would be connected through the surface of the light source 1.

[0137] The above is an introduction to the scheme shown in Figure 12. The scheme shown in Figure 13 will be introduced below.

[0138] Referring to Figure 13, the optical waveguide 26 is horizontally located on the light-emitting surface of the light source 1, and the transmission direction of the optical waveguide 26 is perpendicular to the light path emitted by the light source 1. In this case, referring to Figure 13, the modulation structure 2 also includes a reflector 27, which is located on the light-emitting surface of the light source 1 and on the light path emitted by the light source 1, while the optical waveguide 26 is located on the light path reflected by the reflector 27.

[0139] Referring again to Figure 13, the modulation layer 21, the first electrode 22, and the electric field forming layer 24 are stacked on the surface of the optical waveguide 26 facing away from the light source 1, with the first electrode 22 located on the outermost side. The second electrode 23 is located on the surface of the optical waveguide 26 facing away from the light source 1.

[0140] For example, referring to Figure 13, the modulation layer 21 is located on the surface of the optical waveguide 26 opposite to the light source 1, the electric field forming layer 24 is located on the surface of the modulation layer 21 opposite to the optical waveguide 26, the first electrode 22 is located on the surface of the electric field forming layer 24 opposite to the modulation layer 21, and the second electrode 23 is located on the surface of the optical waveguide 26 opposite to the light source 1. A portion of the second electrode 23 may extend into the modulation layer 21, or it may not. Thus, as shown in Figure 13, a large number of negatively charged carriers accumulate at the interface between the optical waveguide 26 and the modulation layer 21, and a large number of positively charged carriers accumulate on the upper surface of the modulation layer 21.

[0141] For example, the electric field forming layer 24 is located on the surface of the optical waveguide 26 facing away from the light source 1, while the modulation layer 21 is located on the surface of the electric field forming layer 24 facing away from the optical waveguide 26. The first electrode 22 is located on the upper surface of the modulation layer 21 facing away from the electric field forming layer 24, and the second electrode 23 is located on the surface of the optical waveguide 26 facing away from the light source 1. A portion of the second electrode 23 may extend into the electric field forming layer 24, or it may not. In this way, a large number of negatively charged carriers accumulate on the lower surface of the modulation layer 21 that is in contact with the electric field forming layer 24, and a large number of positively charged carriers accumulate on the upper surface of the modulation layer 21.

[0142] In one example, since the continuous light is modulated during transmission in the optical waveguide 26, the electro-optic modulation effect is better if the refractive index of the modulation layer 21 changes along the transmission direction of the optical waveguide 26. Therefore, referring to Figure 13, the lengths of the modulation layer 21 and the electric field forming layer 24 are both equal to the length of the optical waveguide 26 in the transmission direction of the optical waveguide 26. Alternatively, the lengths of the modulation layer 21 and the electric field forming layer 24 are both slightly smaller than the length of the optical waveguide 26 in the transmission direction of the optical waveguide 26.

[0143] In one example, whether it's the scheme shown in Figure 12 or Figure 13, a change in the refractive index of the modulation layer 21 covering the optical waveguide 26 will alter the propagation characteristics of the laser within the waveguide 26. For instance, it may cause the laser to attenuate within the waveguide 26, resulting in a weaker laser beam being output. Thus, during modulation, the refractive index of the modulation layer 21 changes, and the optical waveguide 26 outputs a weaker laser beam; during non-modulation, the refractive index of the modulation layer 21 remains constant, and the optical waveguide 26 outputs a stronger laser beam, thereby achieving pulsed light output from the optical waveguide 26 and realizing electro-optic modulation.

[0144] In this embodiment, the electro-optic modulator uses a modulation structure to modulate continuous light emitted from a light source into pulsed light, thereby increasing the modulation bandwidth of the electro-optic modulator, which is unaffected by the parameters of the light source itself. For example, if a surface-emitting laser is used as the light source, the modulation bandwidth of the electro-optic modulator is unaffected by the relaxation frequency, parasitic resistance, and parasitic capacitance of the surface-emitting laser, thus increasing the modulation bandwidth of the surface-emitting laser. The modulation structure includes a modulation layer. Applying a voltage to the modulation layer generates an electric field within it, increasing the carrier concentration and changing the refractive index, thereby affecting the optical properties of the modulation layer and converting the continuous light emitted by the surface-emitting laser into pulsed light, achieving electro-optic modulation. Furthermore, the modulation bandwidth can be increased by changing the characteristics of the modulation structure. For example, the modulation layer can use a TCO with a near-zero dielectric constant effect, or multiple electric fields can be formed within the modulation layer.

[0145] The terminology used in the embodiments of this disclosure is for illustrative purposes only and is not intended to limit the disclosure. Unless otherwise defined, the technical or scientific terms used in the embodiments of this disclosure should be understood in their ordinary sense by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar terms used in this specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "an," and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising," "including," and similar terms mean that the elements or objects preceding "comprising" or "including" encompass the elements or objects listed following "comprising" or "including" and their equivalents, but do not exclude other elements or objects. "Upper," "lower," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly. "A plurality" refers to two or more, unless otherwise expressly defined.

[0146] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. An electro-optic modulator, characterized in that, The electro-optic modulator includes a light source (1) and a modulation structure (2), wherein the modulation structure (2) is located in the outgoing light path of the light source (1); The modulation structure (2) includes a modulation layer (21), a first electrode (22), a second electrode (23), and an electric field forming layer (24). The first electrode (22), the second electrode (23), and the electric field forming layer (24) are used to generate an electric field on the modulation layer (21) to change the carrier concentration of the modulation layer (21).

2. The electro-optic modulator according to claim 1, characterized in that, The modulation layer (21) is located in the outgoing light path of the light source (1); The modulation layer (21) has a first electrode (22) arranged on the first side near the light source (1) and a second electrode (23) arranged on the second side away from the light source (1). The electric field forming layer (24) is arranged between the first electrode (22) and the second electrode (23). The first side and the second side of the modulation layer (21) are two sides of the modulation layer (21) that are positioned opposite each other in the transmission direction of the light source (1).

3. The electro-optic modulator according to claim 2, characterized in that, The number of the first electrode (22) is multiple. The first electrode (22) is arranged on the first side of the modulation layer (21) and in the modulation layer (21) between the first side and the second side. The electric field forming layer (24) is arranged between the second electrode (23) and the first electrode (22) closest to the second electrode (23).

4. The electro-optic modulator according to claim 2, characterized in that, The number of the first electrode (22), the second electrode (23), and the electric field forming layer (24) are all multiple; The first electrode (22) and the second electrode (23) are alternately arranged on the first side of the modulation layer (21), in the modulation layer (21), and on the second side of the modulation layer (21), and the electric field forming layer (24) is arranged between the adjacent first electrode (22) and second electrode (23).

5. The electro-optic modulator according to any one of claims 2 to 4, characterized in that, The modulation layer (21) has a modulation region (211), the modulation region (211) and the light source (1) are positioned opposite each other, and the first electrode (22) extends into the modulation region (211).

6. The electro-optic modulator according to any one of claims 2 to 5, characterized in that, The modulation structure (2) is located on the light-emitting surface of the light source (1), and the first electrode (22) and the second electrode (23) are both offset from the light path emitted by the light source (1).

7. The electro-optic modulator according to claim 6, characterized in that, Both the first electrode (22) and the second electrode (23) are ring electrodes, and the outgoing light path of the light source (1) is located in the space inside the ring of the first electrode (22) and the second electrode (23).

8. The electro-optic modulator according to any one of claims 2 to 5, characterized in that, The modulation structure (2) is located above the light-emitting surface of the light source (1), and there is a distance H between the modulation structure (2) and the light-emitting surface of the light source (1); The second electrode (23) on the second side of the modulation layer (21) is located in the outgoing light path of the light source (1), and the other electrodes below the second electrode (23) on the second side of the modulation layer (21) are all offset from the outgoing light path of the light source (1). The modulation structure (2) further includes a grating layer (25), which is located below the second electrode (23) on the second side of the modulation layer (21).

9. The electro-optic modulator according to claim 1, characterized in that, The modulation structure (2) further includes an optical waveguide (26), which is located on the light-emitting surface of the light source (1) and in the light-emitting path of the light source (1); The modulation layer (21) and the electric field forming layer (24) are stacked on the surface of the optical waveguide (26) perpendicular to the transmission direction.

10. The electro-optic modulator according to claim 9, characterized in that, The optical waveguide (26) and the second electrode (23) are both located on the light-emitting surface of the light source (1), and the optical waveguide (26) and the second electrode (23) are connected. The optical waveguide (26) is perpendicular to the light path emitted by the light source (1). The modulation layer (21), the first electrode (22) and the electric field forming layer (24) are superimposed and circumferentially covered on the outer surface of the optical waveguide (26), with the first electrode (22) located on the outermost layer.

11. The electro-optic modulator according to claim 9, characterized in that, The modulation structure (2) further includes a reflector (27), which is located on the light-emitting surface of the light source (1) and on the light path of the light source (1). The optical waveguide (26) is horizontally located on the light-emitting surface of the light source (1) and on the light path of the reflector (27). The modulation layer (21), the first electrode (22) and the electric field forming layer (24) are stacked on the surface of the optical waveguide (26) opposite to the light source (1), with the first electrode (22) located on the outermost side; the second electrode (23) is located on the surface of the optical waveguide (26) opposite to the light source (1).

12. The electro-optic modulator according to any one of claims 1 to 11, characterized in that, The light source (1) is a surface-emitting laser.

13. The electro-optic modulator according to any one of claims 1 to 12, characterized in that, The modulation layer (21) is made of transparent conductive oxide (TCO).

14. The electro-optic modulator according to any one of claims 1 to 13, characterized in that, The electric field forming layer (24) is made of silicon oxide, aluminum oxide or hafnium dioxide.

15. An optical device, characterized in that, The optical device includes the electro-optic modulator according to any one of claims 1 to 14.

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