JP2016038399A - Optical modulation method, optical modulator manufacturing method, optical modulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical modulation method that can allow both high modulation efficiency and power saving.SOLUTION: The optical modulation method includes: forming an n layer 11, and a pseudo p layer 12 into which a p-type dopant is implanted; generating diffusion current in the n layer 11 and the pseudo p layer 12 by applying a forward bias voltage; repeatedly changing the distribution of the p-type dopant implanted into any one or more of the pseudo p layers 12 based on Joule heat generated by the generated diffusion current, and reducing the diffusion current to lower the Joule heat at a site where near-field light is generated, based on the distribution of the changed p-type dopant; fixing the dopant distribution in the pseudo p layer 12 and configuring the pseudo p layer 12 as p-type semiconductor 21; and causing light to propagate through the p-type semiconductor 21 and applying a modulation electric field to the light in a propagation direction and in a substantially vertical direction, thereby modulating the polarization direction or the propagation direction of the light.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an optical modulation method for modulating the polarization direction or propagation direction of propagating light, an optical modulator manufacturing method, and an optical modulator.

  With the development of optoelectronics in recent years, there has been a demand for laser light control for frequency multiplex communication, a frequency measurement of absorption lines distributed over a wide range, and a request from the field of optical information processing such as optical communication and optical recording. In order to respond, a waveguide-type optical modulator that modulates light resonated in a waveguide is widely used (for example, refer to Patent Document 1). In the optical waveguide constituting this waveguide type optical modulator, it is possible to control the polarization direction of light by utilizing the magneto-optic effect such as the Faraday effect and the Kerr effect. By selecting the material, it is possible to realize a response speed of the order of several tens of ns.

  On the other hand, it is necessary to select a magnetic material for exhibiting such a magneto-optical effect, and an external magnetic field of several T scale is required to obtain a sufficient amount of modulation due to the magnetization characteristics of such a magnetic material. It is necessary to provide a device that generates

  For this reason, the light modulation using the existing magneto-optical effect has a problem that it is impossible to achieve both modulation efficiency and energy saving.

JP 2005-148389 A

  Therefore, the present invention has been devised in view of the above-described problems, and an object of the present invention is to produce an optical modulation method and an optical modulator that can achieve both modulation efficiency and energy saving. A method and an optical modulator are provided.

  The light modulation method according to claim 1, wherein an n layer composed of an n-type oxide semiconductor substrate and a pseudo p-layer in which a p-type dopant is implanted in the n-type oxide semiconductor substrate are formed, and a forward bias voltage is set. By applying a diffusion current to the n layer and the pseudo p layer, a distribution of the p-type dopant implanted in one or more of the pseudo p layers based on Joule heat generated by the generated diffusion current is generated. In the place where near-field light is generated based on the distribution of the p-type dopant after the change, the forward bias voltage causes an inversion distribution in the conduction band and the valence band in the active layer. , By causing the electrons in the conduction band forming the inversion distribution to undergo stimulated emission in multiple stages based on a non-adiabatic process, thereby reducing the diffusion current and The pseudo heat is decreased, the dopant distribution in the pseudo p layer is fixed, the pseudo p layer is configured as a p-type oxide semiconductor, and light is propagated to the p-type oxide semiconductor, and the light is propagated. The polarization direction or propagation direction of the light is modulated by applying a modulation electric field in a direction substantially perpendicular to the direction.

  According to a second aspect of the present invention, there is provided the light modulation method according to the first aspect of the present invention, wherein when the forward bias voltage is applied, guided light having a wavelength longer than the band gap of the p-type dopant is applied to the pseudo-p layer. Irradiation is performed, and light having substantially the same wavelength as that of the guide light is propagated.

  According to a third aspect of the present invention, there is provided the optical modulation method according to the first or second aspect, wherein near-field light is generated by the propagating light based on the distribution of the p-type dopant after the change. While the propagation of light by light is temporarily converted into dressed photons, the propagation is delayed, and the polarization is biased by applying a magneto-optic effect based on the modulated electric field to the dressed photons. It is characterized by modulating the propagating light converted again from.

  According to a fourth aspect of the present invention, there is provided a method for manufacturing an optical modulator, comprising: forming an n layer composed of an n-type oxide semiconductor substrate; and a pseudo p layer in which a p-type dopant is implanted in the n-type oxide semiconductor substrate. A p-type dopant implanted in any one or more of the pseudo p layers based on Joule heat generated by the diffusion current generated by applying a bias voltage to generate a diffusion current in the n layer and the pseudo p layer. Is repeated, and the forward bias voltage causes inversion distribution in the conduction band and valence band in the active layer, and near-field light is generated based on the distribution of the p-type dopant after the change. In these locations, electrons in the conduction band forming the inversion distribution are stimulated and emitted in multiple steps based on a non-adiabatic process, thereby reducing the diffusion current. The Joule heat is lowered, the dopant distribution in the pseudo p layer is fixed, the pseudo p layer is configured as a p-type oxide semiconductor, and the propagation direction of light propagating to the p-type oxide semiconductor is substantially the same. A modulation electric field application unit for applying a modulation electric field in the vertical direction is provided.

  An optical modulator according to claim 5 is manufactured by the method for manufacturing an optical modulator using an oxide semiconductor according to claim 4, and is substantially perpendicular to a propagation direction of light to be modulated to be propagated to the p-type oxide semiconductor. And a modulation electric field applying means for applying a modulation electric field, wherein the modulation electric field applying means modulates the polarization direction or propagation direction of the light to be modulated by applying the modulation electric field.

  The optical modulator according to claim 6 is the optical modulator according to claim 5, wherein when the forward bias voltage is applied, guided light having a wavelength longer than the band gap of the p-type dopant is applied to the pseudo p layer. When irradiated, light having substantially the same wavelength as that of the guide light is propagated.

  According to a seventh aspect of the present invention, in the optical modulator according to the fifth or sixth aspect of the invention, the near-field light generated by the propagating light is generated based on the distribution of the p-type dopant after the change. While the propagation of light by light is temporarily converted into dressed photons, the propagation is delayed, and the polarization is biased by applying a magneto-optic effect based on the modulated electric field to the dressed photons. It is characterized by modulating the propagating light converted again from.

  According to the present invention having the above-described configuration, it is possible to generate near-field light by propagating the propagation light to be modulated having substantially the same wavelength as that of the guide light to the pseudo-p layer. That is, the energy of light propagating in the pseudo p layer is temporarily converted into dressed photons (near field light) as a localized field. By converting to dressed photons, the speed of reaching the n-layer is slower compared to normal propagating light. Thus, during the conversion into dressed photons, the magnetic field due to the modulation electric field is applied. By applying a modulation electric field, the magneto-optical effect due to magnetism caused by p-type ZnO is received. However, since the time remaining in the pseudo-p layer is longer than that of propagating light, the magneto-optical effect is increased. Longer time to receive the effect. As a result, the dressed photons are largely polarized due to the magneto-optic effect. In response to this, it becomes possible to change the polarization direction of the propagating light converted again from the dressed photon. In particular, according to the present invention, the dressed photon continues to receive the magneto-optical effect for a longer time, so that the polarization changes greatly, and the polarization direction can be greatly modulated accordingly. Even when the pseudo p-layer is formed with a small thickness of several μm, the dressed photons can be modulated with high efficiency without being controlled by the thickness.

It is a block diagram of the manufacturing apparatus of the optical modulator to which this invention is applied. It is an energy band figure of n layer and pseudo p layer. It is a figure which shows the example after the distribution change of a dopant arises. It is the figure which showed the non-adiabatic process with the model which replaced the coupling | bonding of atoms with the spring. (A) is an example in which an inversion distribution based on the difference in electron density is formed in the vicinity of the n layer in the pseudo-p layer, and (b) is based on a non-adiabatic process of electrons in the conduction band by near-field light. It is a figure which shows the example made to light-emit by making it discharge | release. It is a figure which shows the example in which the micro area | region B of the same distribution as the micro area | region A is formed. It is a block diagram of the optical modulator to which this invention is applied. (A) is a figure which shows the example converted temporarily into the dressed photon (near field light) as a localized field in a pseudo | simulation p layer, (b) is as it is, without converting propagating light into a dressed photon. It is a figure which shows the example made to propagate.

  Hereinafter, an optical modulator to which the present invention is applied and a manufacturing method thereof. The light modulation method will be described in detail with reference to the drawings.

  FIG. 1 is a configuration diagram of an optical modulator manufacturing apparatus 10 to which the present invention is applied. The manufacturing apparatus 10 includes a pn junction 1 and a power supply 41 for applying a voltage to the pn junction 1.

  The pn junction 1 is made of ZnO and includes an n layer 11 and a pseudo p layer 12. The n layer 11 is an n-type semiconductor composed of an n-type ZnO substrate. The n layer 11 is obtained by doping a group III element such as aluminum or a halogen element with respect to an n-type ZnO substrate.

The pseudo p layer 12 is an n-type ZnO substrate implanted with nitrogen as a p-type dopant with high density and high energy. The pseudo p layer 12 may have a doping density of about 10 ¹⁹ in the vicinity of, for example, 700 KeV and 500 nm from the surface. Incidentally, since nitrogen as a dopant lacks stability, the pseudo p layer 12 often does not stably act as a so-called p-type semiconductor. That is, most of the nitrogen as a dopant in the pseudo p layer 12 is not fixed at a position in the crystal that should function as an acceptor. However, since nitrogen is added as a p-type dopant, it is defined as a pseudo p layer 12 as a pseudo p layer.

  In the method of manufacturing an optical modulator to which the present invention is applied, the dopant distribution of nitrogen as a dopant in ZnO of the pseudo p layer 12 in the pn junction 1 is changed. The change in the dopant distribution here is a concept including all phenomena caused by annealing, such as a change in the position of initially implanted nitrogen or a diffusion of the implanted nitrogen.

  In the pseudo p layer 12, a dopant 14 made of nitrogen is implanted. However, this dopant distribution is unstable and cannot function as a so-called p-type semiconductor.

  Actually, a forward bias voltage is applied to the pn junction 1. As a result, the optical modulator according to the present invention can be manufactured based on the following mechanism.

  FIG. 2 shows an energy band diagram of the n layer 11 and the pseudo p layer 12. When a forward bias voltage is applied, holes in the pseudo p layer 12 move to the n layer 11 side, and electrons in the n layer 11 move to the pseudo p layer 12 side. As a result, a diffusion current flows by mutual cancellation of electrons and holes. When the forward bias voltage is high, Joule heat is generated due to the movement of the electrons. The particularly large generation site of the Joule heat is centered on the interface between the n layer 11 and the pseudo p layer 12 that generates a large potential difference. However, at least in the vicinity of the n layer 11 in the pseudo p layer 12, the potential difference is large. Occurs. By increasing this forward bias voltage, an avalanche breakdown occurs in the vicinity of the n layer 11 in the pseudo p layer 12, and current flows at once. As a result, heat generation due to Joule heat is promoted by such avalanche breakdown.

  As a result of the generation of the Joule heat, the fluidity increases in the pseudo p layer 12, particularly in the vicinity of the n layer 11, and the distribution of the dopant 14 changes. By continuing to apply the forward bias voltage described above, the distribution change of the dopant 14 continuously occurs.

  FIG. 3 shows an example after the distribution change of the dopant 14 occurs. The generation of Joule heat increases the fluidity in the pseudo p layer 12, particularly in the vicinity of the n layer 11. As a result, the distribution of the dopant in the vicinity of the n layer 11 in the pseudo p layer 12 changes randomly. As a result of repeated changes in the surface shape and dopant distribution, for example, a specific dopant distribution is formed in the fine region A. This unique dopant distribution in the fine region A is a distribution that is more suitable for generating near-field light based on guided light as incident propagating light. The conditions for forming this specific dopant distribution are not established, and as a result of random changes of the dopant in the vicinity of the n layer 11 in the pseudo p layer 12 due to the generation of Joule heat, it occurs by chance under a certain probability. Is formed.

  When such a specific dopant distribution in the fine region A is formed, if the above-described forward bias voltage is further loaded, near-field light is generated in the specific dopant distribution. The near-field light here includes the meaning of a virtual electromagnetic field, and therefore the formation of a virtual electromagnetic field is understood as meaning the generation of near-field light. The generation of the near-field light is generated by spontaneous emission of the injected charge and stimulated emission based on it when the forward current is injected, even in the absence of the induced light. Generation of this near-field light causes a non-adiabatic process described below. Incidentally, the generation position of the near-field light is generated at a place where the specific dopant distribution is generated, but may naturally occur at other places.

  This non-adiabatic process can be considered by a model in which the bonds between atoms are replaced by springs as shown in FIG. In general, the wavelength of propagating light is much larger than the size of the molecule, so it can be regarded as a spatially uniform electric field at the molecular level. As a result, as shown in FIG. 4A, adjacent electrons are vibrated with the same amplitude and the same phase by the spring. Since the atomic nucleus of ZnO is heavy, it cannot follow the vibrations of the electrons, and molecular vibrations are extremely difficult to occur in the propagating light. In this way, in propagation light, it can be ignored that molecular vibrations are involved in the excitation process of electrons, so this process is called adiabatic process.

  On the other hand, the spatial electric field gradient of near-field light drops very steeply. For this reason, near-field light gives different vibrations to adjacent electrons, and as shown in FIG. 4B, the heavy nuclei are also vibrated by the vibrations of the different electrons. The occurrence of molecular vibration in the near-field light corresponds to energy taking the form of molecular vibration. Therefore, in the near-field light, an excitation process (non-adiabatic process) via the vibration level is possible. In this way, the excitation process via the vibration level of the nucleus is called a non-adiabatic process because the nucleus moves in response to the adiabatic process, which is a normal optical response.

Further, by continuing to apply the forward bias voltage described above, the electron density n ₁ in the conduction band is overwhelmingly higher than the hole density n ₂ in the lower level. As a result, an inversion distribution based on the difference in electron density is formed in the vicinity of the n layer 11 in the pseudo p layer 12 between the conduction band and the lower level, as shown in FIG. Next, due to this inversion distribution, electrons in the conduction band are virtually transitioned to a vibration level located in the middle of the band gap based on a non-adiabatic process by near-field light. Can be made. The fact that the electrons were able to transit to the vibration level based on the non-adiabatic process was realized because near-field light was generated at that location. This near-field light is generated by a change in dopant that occurs with a certain probability due to the flow due to Joule heat. The electrons that have transitioned to the vibration level travel around the virtual field (dressed photon-phonon level) virtually generated by the near-field light, and then return from the vibration level to the conduction band. The electrons returning to the conduction band contribute to Joule heat due to the diffusion current.

  Thus, at the stage where the near-field light is simply generated, the electrons in the conduction band are virtually transitioned to the vibration level and returned to the conduction band again. The electrons returning to the conduction band contribute to Joule heat, and the Joule heat does not decrease, and the distribution change of the dopant in the vicinity of the n layer 11 in the pseudo p layer 12 continues.

  As a result of the change in the distribution of the dopant due to Joule heat, when the generation mode of the near-field light further changes, as shown in FIG. Based on a non-adiabatic process by light, light is emitted by virtually transitioning to a vibration level located in the middle of the band gap and emitting electrons therefrom. Further, light is emitted by stimulated emission of electrons in the conduction band in a plurality of steps based on such near-field light.

As a result, it is possible to realize light emission by emitting electrons from the pn junction 1. In the specific dopant distribution, near-field light continues to be generated, so that a non-adiabatic process can be generated. In stimulated emission by this non-adiabatic process, electrons are emitted through vibration levels. At this time, even in the induced light having a wavelength longer than the absorption edge wavelength corresponding to the band gap width, electrons in the conduction band can be emitted in a multi-stage transition, and as a result, electrons in the conductor are reduced. It becomes possible. That is, the above-described stimulated emission is generated by irradiating the pseudo-p layer with induced light having a wavelength longer than the excitation wavelength of the p-type dopant.
The multistage stimulated emission caused by such a non-adiabatic process causes the electron density n ₁ in the conduction band to decrease. As a result, in the region where the peculiar dopant distribution in which such near-field light is generated is formed, the amount of electrons moving to the n layer 11 decreases, and the diffusion current decreases. And the Joule heat falls about the area | region in which the said specific dopant distribution was formed. That is, stimulated emission takes away energy of electrons and holes, and the fluidity in the vicinity of the n layer 11 in the pseudo p layer 12 decreases. As a result, the change in dopant distribution is suppressed in the vicinity of the n layer 11 in the pseudo p layer 12. Such a dopant distribution is fixed without change.

  Further, when light emission occurs as shown in FIG. 5B, near-field light due to a specific dopant distribution is likely to be generated based on the light emission. The generated near-field light further tends to cause a non-adiabatic process in each part, and the fixation of the specific dopant distribution and the light emission are promoted.

  Moreover, the mechanism described above is continuously generated by continuing to apply the forward bias voltage as described above.

  In the fine region A, the near-field light continues to be generated as it is, and the stimulated emission by the non-adiabatic process described above is continuously generated. As a result, the temperature is lowered, and the fine region A continues to be fixed in this state. In addition, since the near-field light is not generated in the portions other than the fine region A, the fluidity in the vicinity of the n layer 11 in the pseudo p layer 12 is increased by generating Joule heat as it is without being cooled. The dopant distribution in the vicinity of the n layer 11 in the pseudo p layer 12 changes randomly. As a result of this random change in dopant distribution, as shown in FIG. 6, a fine region B having the same distribution as the fine region A may be formed. Similar to the fine region A, the specific dopant distribution in the fine region B is a more suitable distribution for generating near-field light. The conditions for forming this specific dopant distribution are not established, and as a result of random changes of the dopant in the vicinity of the n layer 11 in the pseudo p layer 12 due to the generation of Joule heat, it occurs by chance under a certain probability. Is formed.

  When such a specific dopant distribution in the fine region B is formed, if the forward bias voltage described above is further applied, near-field light is generated in the specific dopant distribution. The generation of the near-field light is generated by spontaneous emission of the injected charge and stimulated emission based on it when the forward current is injected, even in the absence of the induced light. The generation of the near-field light causes a similar non-adiabatic process in the fine region B.

  Also in the fine region B, the diffusion current is reduced due to multistage stimulated emission due to the non-adiabatic process. And about the micro area | region B in which the said specific dopant distribution was formed, Joule heat will fall and fluidity | liquidity will fall. As a result, also in the fine region B, the change in the dopant distribution is suppressed in the vicinity of the n layer 11 in the pseudo p layer 12. Such a dopant distribution is fixed without change.

  When such processing is repeatedly executed, ideally, many dopant distributions identical to those in the fine regions A and B in which near-field light is suitably generated when a forward bias voltage is applied are created. The change in the dopant distribution is suppressed, and the processing by improving the fluidity is stopped. As a result, the luminous efficiency can be dramatically improved.

  Thus, in the present invention, since most of the implanted nitrogen is not fixed at a position in the crystal that should function as an acceptor, a forward bias voltage is applied in the pseudo-p layer 12 that does not function stably as a p-layer. As a result, the fluidity of the pseudo p-layer 12 due to the generation of Joule heat is increased. Then, the near-field light is generated when the distribution of the dopant in the vicinity of the n layer 11 in the pseudo p layer 12 randomly changes and a specific dopant distribution is formed. And in the area | region where the said near field light generate | occur | produced, light emission arises by stimulated emission. In a region where light emission due to the generation of such near-field light occurs, the fluidity is lowered, the processing is stopped, and the dopant distribution is fixed.

  In a state where this dopant is fixed, light emission occurs when a forward bias voltage is applied, so that it functions as a so-called pn junction. That is, it means that the dopant in the vicinity of the n layer 11 in the pseudo p layer 12 has moved and fixed to a position in the crystal that should function as an acceptor.

  Although the pseudo p layer 12 is composed of ZnO from the beginning, when nitrogen as a dopant in the pseudo p layer 12 moves to a position in the crystal that should function as an acceptor, ZnO becomes a p-type semiconductor. Will function. Therefore, it can be said that the fine regions A and B in which the near-field light is suitably generated in the pseudo p layer 12 are changed to so-called p-type ZnO.

  In particular, in the present invention, the n layer 11 and the vicinity thereof in the pseudo p layer 12 are once flowed based on Joule heat, and then the dopant is moved and solidified to a state where the function as a p-type semiconductor can be exhibited. Thereby, the diffused and fixed dopant is stably fixed in a state capable of exhibiting a function as a p-type semiconductor in ZnO. For this reason, the pseudo p layer 12 can be changed to a p layer that exhibits the function of the original p-type semiconductor 21.

  Next, light modulation is performed using the p-type semiconductor 21 thus obtained. In such a case, an optical modulator 40 as shown in FIG. 7 is configured, and light to be modulated is propagated to the p-type semiconductor 21. In such a case, the input light is irradiated from the side of the pseudo p layer 12, passes through the p-type semiconductor 21, and propagates to the n layer 11. When a reflection type light modulator is configured, for example, a metallic thin film 25 as a reflection film may be formed on the end face of the n layer 11. As a result, the light that has passed through the p-type semiconductor 21 and propagated to the n-layer 11 is reflected by the metallic thin film 25, propagates from the n-layer 11 through the p-type semiconductor 21, and is emitted to the outside. Become. On the other hand, when a transmissive optical modulator is configured, the modulation is performed by allowing the light to be modulated to pass in one direction by omitting the configuration of the metallic thin film 25.

  In both the reflection type and transmission type optical modulators, the light propagation direction is perpendicular to the pn junction plane 28.

  In addition, a modulation electric field is applied in a direction substantially perpendicular to the light propagation direction. The modulation electric field is applied through a modulation electric field application unit 22 as shown in FIG. The modulation electric field applying unit 22 includes two electrodes provided on the surface of the pseudo p layer 12. A modulation electric field is applied through the modulation electric field applying unit 22. As a result, the modulation electric field flows in the pseudo p layer 12. In particular, by arranging two modulation electric field application sections 22 so that a current based on the modulation electric field flows in a direction substantially parallel to the pn junction surface 28, the modulation electric field and the light propagation direction are substantially perpendicular to each other. It becomes possible to adjust to be in the direction.

  In this way, the polarization direction or the propagation direction of the light can be modulated by applying a modulation electric field in a direction substantially perpendicular to the propagation direction of the light.

  In particular, it is possible to generate near-field light by propagating the propagation light to be modulated having substantially the same wavelength as that of the guide light to the pseudo-p layer 12. The fine regions A and B constituting the pseudo p layer 12 have a dopant distribution capable of generating near-field light with respect to the wavelength of the guide light. For this reason, it is possible to generate near-field light through the fine regions A and B by irradiating the pseudo-p layer 12 composed of the fine regions A and B with propagation light having substantially the same wavelength as the guide light. It becomes.

  That is, the energy of light propagating in the pseudo p layer 12 is temporarily converted into dressed photons (near field light) as a localized field in the pseudo p layer 12 as shown in FIG. This temporarily converted dressed photon has a so-called localized property of staying in place temporarily. For this reason, the speed | rate which reaches | attains the n layer 11 becomes slow compared with normal propagation light by converting into a dressed photon. The temporarily converted dressed photons are then converted again into propagating light and propagated to the n layer 11 as shown in FIG. 8A.

  Thus, during the conversion into dressed photons, the magnetic field due to the above-described modulation electric field is applied. By applying a modulation electric field, the magneto-optical effect due to magnetism caused by p-type ZnO is received. In this magneto-optical effect, for example, the refractive index and the polarization plane change due to a magnetic field. The dressed photon continues to receive this magneto-optic effect, but the time spent in the pseudo-p layer 12 is longer than that of the propagating light, and thus the time to continue receiving the magneto-optical effect is also increased. As a result, the dressed photons are largely polarized due to the magneto-optic effect. In response to this, it becomes possible to change the polarization direction of the propagating light converted again from the dressed photon. In particular, according to the present invention, the dressed photon continues to receive the magneto-optical effect for a longer time, so that the polarization changes greatly, and the polarization direction can be greatly modulated accordingly. Even when the pseudo p layer 12 is formed with a slight thickness of several μm, the dressed photons can be modulated with high efficiency without being controlled by the thickness.

  Incidentally, the modulation referred to here may be not only the above-described modulation in the polarization direction but also the modulation in the propagation direction, and includes any other modulation. Further, the propagation light to be modulated is not limited to the case where it has substantially the same wavelength as the guide light. Even if the wavelength of the propagation light to be modulated is different from the wavelength of the guide light, near-field light may be generated. In such a case, the same effect as described above will occur.

  On the other hand, as shown in FIG. 8B, if the propagating light propagates as it is without being converted into dressed photons, the period is shortened even if the magneto-optical effect is received. Highly efficient modulation cannot be realized.

  According to the present invention, in addition to the modulation mechanism described above, modulation by a mechanism described below may be performed. In such a case, the point that the propagation light is temporarily converted into a delayed photon, delayed, and then converted again into the propagation light and propagated to the n layer 11 is the same as described above. At this time, the polarization of the pseudo p layer 12 in ZnO is biased by the modulation electric field. That is, the polarization photons caused by the ZnO material are tinged with the dressed photons. The polarization of the dressed photon itself changes greatly due to the polarization caused by this material, and the polarization direction of the propagating light converted from the dressed photon can be changed.

  In addition, according to the optical modulator 40 to which the present invention having the above-described configuration is applied, it is not necessary to use an external magnetic field, so that energy saving, resource saving, and cost reduction can be achieved.

  In addition, the present invention may be embodied as the optical modulator 40 having the above-described configuration, or may be embodied as a method for manufacturing the optical modulator 40. Furthermore, according to the present invention, it is needless to say that the present invention may be embodied as a series of light modulation methods from the production of the light modulator 40 to the modulation operation.

DESCRIPTION OF SYMBOLS 1 pn junction body 10 Preparation apparatus 11 N layer 12 Pseudo p layer 14 Dopant 21 P-type semiconductor 22 Modulation electric field application part 25 Metal thin film 28 pn junction surface 40 Optical modulator 41 Power supply

Claims (7)

forming an n layer composed of an n-type oxide semiconductor substrate and a pseudo-p layer in which a p-type dopant is implanted in the n-type oxide semiconductor substrate;
A diffusion current is generated in the n layer and the pseudo p layer by applying a forward bias voltage;
Based on Joule heat generated by the generated diffusion current, the distribution of the p-type dopant implanted in any one or more of the pseudo-p layers is repeated, and the conduction band in the active layer is generated by the forward bias voltage. And inversion distribution in the valence band,
In a place where near-field light is generated based on the distribution of the p-type dopant after the change, electrons in the conduction band forming the inversion distribution are stimulated and emitted in multiple steps based on a non-adiabatic process. Reducing the diffusion current to reduce the Joule heat, fixing the dopant distribution in the pseudo-p layer, and configuring the pseudo-p layer as a p-type oxide semiconductor,
Further, the light modulation is characterized in that the light is propagated to the p-type oxide semiconductor and the polarization direction or the propagation direction of the light is modulated by applying a modulation electric field in a direction substantially perpendicular to the propagation direction of the light. Method. When applying the forward bias voltage, the pseudo p layer is irradiated with guided light having a wavelength longer than the band gap of the p-type dopant,
The light modulation method according to claim 1, wherein light having substantially the same wavelength as that of the guide light is propagated. The propagation light generates near-field light based on the changed distribution of the p-type dopant, and the propagation light is delayed by temporarily converting the propagated light into dressed photons by the generated near-field light. The polarization light is biased by giving the dressed photon a magneto-optic effect based on the modulated electric field, and the propagating light converted again from the dressed photon is modulated. The light modulation method described. forming an n layer composed of an n-type oxide semiconductor substrate and a pseudo-p layer in which a p-type dopant is implanted in the n-type oxide semiconductor substrate;
A diffusion current is generated in the n layer and the pseudo p layer by applying a forward bias voltage;
Based on Joule heat generated by the generated diffusion current, the distribution of the p-type dopant implanted in any one or more of the pseudo-p layers is repeated, and the conduction band in the active layer is generated by the forward bias voltage. And inversion distribution in the valence band,
In a place where near-field light is generated based on the distribution of the p-type dopant after the change, electrons in the conduction band forming the inversion distribution are stimulated and emitted in multiple steps based on a non-adiabatic process. Reducing the diffusion current to reduce the Joule heat, fixing the dopant distribution in the pseudo-p layer, and configuring the pseudo-p layer as a p-type oxide semiconductor,
A method for manufacturing an optical modulator, further comprising: a modulation electric field applying unit for applying a modulation electric field in a direction substantially perpendicular to a propagation direction of light propagating to the p-type oxide semiconductor. It is produced by the production method of an optical modulator using an oxide semiconductor according to claim 4,
Modulation electric field applying means for applying a modulation electric field in a direction substantially perpendicular to the propagation direction of the light to be modulated propagated to the p-type oxide semiconductor,
The modulation electric field applying means modulates the polarization direction or propagation direction of the light to be modulated by applying a modulation electric field. When the forward bias voltage is applied, when the pseudo-p layer is irradiated with guide light having a wavelength longer than the band gap of the p-type dopant, light having substantially the same wavelength as the guide light propagates. The optical modulator according to claim 5, wherein: The propagation light generates near-field light based on the changed distribution of the p-type dopant, and the propagation light is delayed by temporarily converting the propagated light into dressed photons by the generated near-field light. The polarization light is biased by applying a magneto-optic effect based on the modulation electric field to the dressed photon, and the propagating light converted again from the dressed photon is modulated. The light modulator described.

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