WO2017010743A1 - Optical transmission module, optical transceiver, and optical communication system including same - Google Patents

Abstract

An embodiment includes an optical transmission module, an optical transceiver, and an optical communication system including the same, the optical transmission module comprising: a light emitting diode; and an optical modulator for modulating first light emitted from the light emitting diode, wherein the light emitting diode and the optical modulator include GaN, and the optical modulator transmits the first light therethrough when a voltage is applied.

Description

Optical transmission module, optical transceiver, and optical communication system comprising the same

Embodiments relate to an optical module, an optical transceiver, and an optical communication system including the same.

Digital transmission systems using fiber optics are the most widely used in the field of wired communication. In operating a wired network or a wired / wireless integrated subscriber network, the wired network performance may be determined by an optical transceiver module (optical transceiver) and other optical components.

An optical transceiver of a general wired optical communication network includes an optical transmission module and an optical reception module, and the optical transmission module may include a light emitting device and an optical modulator.

In general, a light emitting device for an optical communication network using a silica optical fiber as a transmission line uses an infrared laser diode (LD) having an oscillation wavelength of 1 μm, and the light emitting device and the optical modulator are free-space connections using a lens, a polymer, etc. The waveguide of the material of the material, or in the process of integrally forming the light emitting device and the optical modulator may be connected by forming a waveguide on the wafer.

Laser diode (LD) can output high-quality light of high output (e.g. light having a narrow half width of spectrum), which is an advantage as a light source for long-distance large capacity optical signal transmission. However, since the operating characteristics of the laser diode LD are sensitive to the ambient temperature, a temperature compensator (TEC) is required to obtain stable operation.

In addition, since the operating characteristics are very unstable when the emitted light is reflected from the surroundings and re-entered into the laser diode LD, the use of an optical isolator is inevitable, and the laser diode LD may The manufacturing cost is also a high problem.

Recently, with the development of network technology, sensor technology, RFID technology and software technology, the Internet of Things (IOT) era is coming. In order to connect many devices, an optical communication network composed of optical transmission / reception modules is essential. Accordingly, there is a need for an optical transceiver module that can operate without a temperature compensation device and an optical isolator even in extreme environments from -50 ° C to 150 ° C. Here, the temperature range of -50 ° C to 150 ° C is an allowable temperature range for the normal operation of the Si IC used in various electronic circuits.

However, laser diodes have a problem in that reliability cannot be guaranteed in various temperature environments without a temperature compensating device and an optical isolator, and have a high price.

The embodiment provides a light transmitting module using a light emitting diode as a light source.

The embodiment provides a horizontal optical transmission module.

The embodiment provides an optical module capable of transmitting a high speed optical signal within a short distance of several tens to hundreds of meters by adjusting the half width of the light spectrum.

The embodiment provides an optical module that can operate at a low temperature of −50 ° C. or less or a high temperature of 150 ° C. or more.

An optical transmission module according to an embodiment of the present invention, a light emitting diode; And an optical modulator for modulating the first light emitted from the light emitting diode, wherein the light emitting diode and the light modulator include GaN, and the light modulator transmits the first light when voltage is applied.

The optical modulator may pass the first light when a reverse bias voltage is applied.

The first light may be light in the visible light wavelength band.

The light emitting diode and the optical modulator may include a nitride semiconductor layer.

The light emitting diode may include a first lower semiconductor layer; An active layer disposed on the first lower semiconductor layer; And a first upper semiconductor layer disposed on the active layer.

The optical modulator includes: a second lower semiconductor layer; A light absorption layer disposed on the second lower semiconductor layer to absorb light output from the light emitting diode; And a second upper semiconductor layer disposed on the light absorption layer.

The active layer and the light absorption layer may include GaN.

The light absorption layer may have a large energy band gap when a reverse bias voltage is applied.

The light absorption layer may have an absorption wavelength band shorter than that of the first light when a reverse bias voltage is applied.

And a filter for adjusting the wavelength width of the first light, wherein the optical modulator modulates the second light passing through the filter, and the half width of the second light is smaller than the half width of the first light.

The full width at half maximum of the first light may be 10 nm to 35 nm.

The half width of the second light may be 2 nm to 10 nm.

The filter includes a first reflecting portion, a cavity, and a second reflecting portion that are sequentially stacked, and the first reflecting portion and the second reflecting portion alternately stack a first optical layer and a second optical layer including different oxides. The cavity may be formed by stacking a plurality of second optical layers, and the cavity may be thicker than the first optical layer or the second optical layer.

The second optical layer may have a higher refractive index than the first optical layer.

The first optical layer may have a refractive index of 1.4 to 1.5, and the second optical layer may have a refractive index of 2.0 to 3.0.

The first optical layer is one of SiO _X (1 ≦ _X ≦ 3) or MgF ₂ , and the second optical layer is formed of TiOx (1 ≦ X ≦ 3), TaOx (1 ≦ X ≦ 3) or ZrO ₂ . It can be one.

The active layer of the light emitting diode and the light absorbing layer of the light modulator may have the same composition.

It may include a first lens disposed between the light emitting diode and the optical modulator.

According to an embodiment, an optical module may be manufactured using a light emitting diode (LED) and an optical modulator. Therefore, since the separate isolator and the temperature control device TEC can be omitted, the manufacturing cost of the optical module can be reduced.

According to an embodiment, the half width of the light spectrum may be adjusted to transmit a high speed optical signal within a short distance of several tens to hundreds of meters.

According to an embodiment, the light emitting diode and the light modulator may be made of a gallium nitride (GaN) -based material to provide an optical module operable even at a high driving temperature.

Various and advantageous advantages and effects of the present invention are not limited to the above description, and will be more readily understood in the course of describing specific embodiments of the present invention.

1 is a conceptual diagram of an optical communication system according to an embodiment of the present invention;

2 is a conceptual diagram of an optical transmission module according to an embodiment of the present invention,

3 is a cross-sectional view of the light emitting diode of FIG.

4 is a modification of FIG. 3,

5 is a cross-sectional view of the filter of FIG. 2,

6 is a graph measuring the reflectance of each filter of the wavelength band,

7 is a graph measuring the wavelength width of the light emitted from the light emitting diode and the wavelength of the light passing through the filter;

8 is a graph measuring the wavelength width of the light passing through the band pass filter,

9 is a conceptual diagram of an optical modulator,

10 is a view illustrating a state in which an energy band gap is changed by applying a reverse bias,

11 is a graph showing a state in which the absorption wavelength band of the optical modulator changes as the reverse bias is applied,

12 is a graph showing a state in which the intensity of light output from a light emitting device changes as a reverse bias is applied;

13 is a conceptual diagram illustrating a process in which an optical signal is modulated by an optical module,

14 is a conceptual diagram of an optical transceiver module according to an embodiment of the present invention;

15 is a conceptual diagram of an optical transmission module according to an embodiment of the present invention;

FIG. 16 is a first modified example of FIG. 15;

FIG. 17 is a second modified example of FIG. 15;

18 is a third modified example of FIG. 16,

19 is a conceptual diagram of an optical receiving module according to an embodiment of the present invention;

20 is a first modification of FIG. 19,

FIG. 21 is a second modified example of FIG. 19;

FIG. 22 is a third modified example of FIG. 19;

23 is a conceptual diagram of an optical transmission module according to another embodiment of the present invention;

FIG. 24 is a first modified example of FIG. 23;

FIG. 25 is a second modified example of FIG. 23;

FIG. 26 is a third modified example of FIG. 23;

27 is a view showing the hollow tube of FIG.

FIG. 28 is a fourth modified example of FIG. 23;

29 is a graph showing the changing wavelength width through the filter.

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail with reference to the accompanying drawings. This embodiment is provided to complete the disclosure of the present invention and to fully inform those skilled in the art to which the present invention pertains, and the present invention is defined by the scope of the claims. . Like reference numerals refer to like elements throughout the specification.

The embodiments may be modified in other forms or in various embodiments, and the scope of the present invention is not limited to the embodiments described below.

Although matters described in a specific embodiment are not described in other embodiments, it may be understood as descriptions related to other embodiments unless there is a description that is contrary to or contradictory to the matters in other embodiments.

For example, if a feature is described for component A in a particular embodiment and a feature for component B in another embodiment, the scope of the present invention is not included if the embodiment in which component A and component B are combined is not explicitly described. It should be understood to belong to.

In addition, the embodiments described herein will be described with reference to cross-sectional views and / or plan views, which are ideal exemplary views of the present invention. In the drawings, the thicknesses of films and regions are exaggerated for effective explanation of technical content. Accordingly, shapes of the exemplary views may be modified by manufacturing techniques and / or tolerances. Therefore, the exemplary embodiments of the present invention are not limited to the specific forms shown, but include changes in forms generated according to manufacturing processes. For example, the etched region shown at right angles may be inclined, rounded, or have a predetermined curvature. Accordingly, the regions illustrated in the figures have schematic attributes, and the shape of the regions illustrated in the figures is intended to illustrate a particular form of region of the device and not to limit the scope of the invention.

1 is a conceptual diagram of an optical communication system according to an exemplary embodiment.

Referring to FIG. 1, an optical communication module according to an embodiment includes a first optical transceiver 3 communicating with a first host 1, a second optical transceiver 4 communicating with a second host 2, and a first optical transceiver 3 communicating with a second host 2. And a channel connected between the first optical transceiver 3 and the second optical transceiver 4.

The first host 1 and the second host 2 are not particularly limited as long as they are various electronic devices that can communicate with each other. For example, the first host 1 may be a controller ECU of the vehicle, and the second host 2 may be various sensors (camera modules, lighting sensors, etc.) disposed in the vehicle.

The first optical transceiver 3 and the second optical transceiver 4 may each be a bidirectional communication module including a transmission module 5 and a reception module 6, but embodiments of the present invention are not necessarily limited thereto. For example, the first optical transceiver 3 may be an optical transmission module and the second optical transceiver 4 may be an optical reception module. Hereinafter, a bidirectional communication method will be described.

The transmission module 5 of the first optical transceiver 3 may be connected by the reception module 6 of the second optical transceiver 4 and the first optical fiber 8. The transmission module 5 may convert an electric signal of the host into an optical signal. The control unit 7 may modulate the optical signal according to the electrical signal of the host. In exemplary embodiments, the controller 7 may include a driver IC.

The receiving module 6 of the first optical transceiver 3 may be connected by the transmitting module 5 of the second optical transceiver 4 and the second optical fiber 9. The receiving module 6 may convert an optical signal into an electrical signal. The controller 7 may amplify the converted electrical signal (TIA) or extract packet information from the electrical signal and transmit the packet information to the host.

In FIG. 1, channels of a transmission signal and a reception signal are differently configured by using the first optical fiber 8 and the second optical fiber 9, but are not necessarily limited thereto. That is, bidirectional communication may be performed using a single optical fiber. In addition, a plurality of first optical modules and a plurality of second optical modules may bidirectionally communicate using a multiplexer. It can also be applied to wireless communication that does not use a wired channel.

2 is a perspective view showing a transmission module according to an embodiment of the present invention.

Referring to FIG. 2, the light transmission module 5 may include a light emitting diode 20, a filter 60, an optical channel 40, an optical modulator 30, and an optical interface 50. The light emitting diode 20, the filter 60, and the optical modulator 30 may be disposed on the carrier substrate 10. However, the present disclosure is not limited thereto, and the light emitting diodes 20, the filters 60, and the optical modulators 30 may be sequentially disposed along the emission direction of the light.

The light emitting diodes 20 and LEDs are insensitive to changes in operating temperature because of large energy band gaps. Therefore, the temperature compensation device can be omitted. When the light emitting diode 20 is a nitride semiconductor, the band gap of the active layer may be about 2.0 to 3.0 eV.

In addition, the light emitting diode 20 generates less noise than the laser diode due to light incident again. Therefore, the optical isolator can be omitted. In addition, the light emitting diode 20 is lower in price than the laser diode. Therefore, when the light emitting diode is used, the manufacturing cost of the optical transmitting module can be lowered.

On the contrary, since the laser diode LD is sensitive to changes in ambient temperature, a temperature compensating device is required to obtain stable operation. When the emitted light is reflected from the surroundings and re-entered into the laser diode LD, the operating characteristic is decreased. Since it becomes very unstable, the use of an optical isolator is inevitable, and the manufacturing cost of the laser diode LD itself has a high problem.

The filter 60 may control the wavelength width (light emission line width) of the light emitted from the light emitting diodes. Since the wavelength of a nitride-based light emitting diode is generally about 20 nm wide, there is a problem that the operating voltage of the optical modulator 30 becomes large in order to obtain a sufficient extinction ratio.

By controlling the wavelength of light using the filter 60, it is possible to transmit a high speed optical signal while achieving a sufficient extinction ratio within a short distance of tens to hundreds of meters.

The optical channel 40 may optically connect the light emitting diodes 20 and the optical modulator 30. Therefore, the light output from the light emitting diode 20 may be provided to the optical modulator 30 through the optical channel 40. The optical channel 40 may be an optical waveguide, but is not limited thereto. For example, the optical channel 40 may be an empty passage through which light may pass, or may be a plurality of optical components (lens, etc.) disposed on the optical path.

The optical modulator 30 may modulate the input light. Hereinafter, the optical modulator 30 will be described as an electro-absorption modulator (EAM), but the configuration of the optical modulator is not necessarily limited thereto.

The field absorption type optical modulator (EAM) can be driven at a low voltage, and the device can be miniaturized. The optical modulator 30 changes the degree of light absorption according to the applied voltage.

The optical modulator 30 may modulate the optical signal by emitting the incident light to the outside or off-state according to a change in the applied voltage.

The optical interface 50 may include a connector connected to an external optical fiber. The optical signal modulated by the optical modulator 30 may be transmitted to the outside through the optical interface 50.

3 is a cross-sectional view of the light emitting diode of FIG. 2.

Referring to FIG. 3, the light emitting diode 20 may include a first substrate 21, a first lower semiconductor layer 22, a first active layer 23, and a first upper semiconductor layer 24.

The first lower semiconductor layer 22, the first active layer 23, and the first upper semiconductor layer 24 may be sequentially stacked on the first substrate 21. The first substrate 21 may include, for example, one of a sapphire substrate, a silicon substrate, a silicon carbide substrate, a plastic substrate, or a glass substrate. The substrate can be removed as needed.

A buffer layer (not shown) may be disposed between the first lower semiconductor layer 22 and the first substrate 21. The buffer layer may mitigate lattice mismatch between the light emitting structure and the first substrate 21.

The buffer layer may have a form in which Group III and Group V elements are combined or include any one of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN. The dopant may be doped in the buffer layer, but is not limited thereto.

The buffer layer may grow as a single crystal on the substrate 21, and the buffer layer grown as the single crystal may improve crystallinity of the first lower semiconductor layer.

The first lower semiconductor layer 22 may be disposed on the first substrate 21. The first lower semiconductor layer 22 may be an n-type semiconductor layer including a gallium nitride (GaN) -based material.

For example, the first lower semiconductor layer 22 may be gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), or aluminum gallium indium nitride (AlxGayInzN, x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ z ≦ 1).

The first lower semiconductor layer 22 may be formed of a nitride doped with an n-type dopant. The n-type dopant may include silicon (Si), germanium (Ge), tin (Sn), or the like. The first lower semiconductor layer 22 may have a structure in which a first layer doped with an n-type dopant and a second layer not doped with an n-type dopant are alternately stacked.

The first lower semiconductor layer 22 may be grown as a single n-type nitride layer. The first electrode 25 may be formed on the upper surface of the exposed first lower semiconductor layer 22. The first electrode 25 may include a Cr / Au film, a Cr / Ni / Au film, a Ti / Al / Au film, or a Ti / Ni / pt / Au film.

The first active layer 23 may be disposed on the first lower semiconductor layer 22. The first active layer 23 may cover a portion of the upper portion of the first lower semiconductor layer 22 and may be spaced apart from the first electrode 25.

The first active layer 23 may generate light by a power source applied from the outside. The generated light may travel to the first lower semiconductor layer 22 and the first upper semiconductor layer 24. The first active layer 23 may have a multi-quantum well (MQW) structure formed of a plurality of quantum well structures.

The first active layer 23 may have a quantum barrier layer and a quantum well layer, and the quantum barrier layer and the quantum well layer of the first active layer 23 of the multi-quantum well structure have different x, y, and z composition ratios, respectively. Aluminum gallium indium nitride (AlxGayInzN, x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1). At this time, the band gap of the quantum well layer should be smaller than the quantum barrier layer, the first lower semiconductor layer 22 and the first upper semiconductor layer 24.

The well layer / barrier layer of the first active layer 23 is at least one of AlGaN / AlGaN, InGaN / GaN, InGaN / InGaN, GaN / AlGaN, InAlGaN / GaN, GaAs (InGaAs) / AlGaAs, GaP (InGaP) / AlGaP It may be formed in a pair structure, but is not limited thereto. The well layer may be formed of a material having a band gap smaller than the band gap of the barrier layer.

The first upper semiconductor layer 24 may be disposed on the first active layer 23. The first upper semiconductor layer 24 may be a p-type semiconductor layer including a gallium nitride (GaN) -based material. For example, the first upper semiconductor layer 24 may be any one of p-type gallium nitride (GaN), p-type aluminum gallium nitride (AlGaN), and p-type aluminum gallium indium nitride (AlGaInN). In addition, the first upper semiconductor layer 24 is formed by stacking at least two of p-type gallium nitride (GaN), p-type aluminum gallium nitride (AlGaN), and p-type aluminum gallium indium nitride (AlGaInN). It may be a structure. The second electrode 26 may be disposed on the first upper semiconductor layer 24.

The second electrode 26 may include a transparent electrode layer, a Cr / Au film, a Ni / Au film, a Ni / Ti / Au film, or a pt / Au film. The transparent electrode layer is made of a transparent conductive oxide, and may be formed of any one of indium tin oxide (ITO), indium oxide (CIO), zinc oxide (ZnO), or nickel oxide (NiO).

An electron blocking layer EBL may be disposed between the first active layer 23 and the first upper semiconductor layer 24. The electron blocking layer blocks the flow of electrons supplied from the first lower semiconductor layer 22 to the first upper semiconductor layer 24, thereby increasing the probability of recombination of electrons and holes in the first active layer 23. Can be. The energy band gap of the electron blocking layer may be greater than the energy band gap of the first active layer 23 and / or the first upper semiconductor layer 24.

The electron blocking layer may be selected from a semiconductor material having a composition formula of Inx1Aly1Ga1-x1-y1N (0≤x1≤1, 0≤y1≤1, 0≤x1 + y1≤1), for example, AlGaN, InGaN, InAlGaN, or the like. It is not limited to this.

Hereinafter, although described as a horizontal light emitting diode, the structure of the light emitting diode according to the embodiment is not limited thereto. For example, the light emitting diode may be a vertical light emitting diode in which a first electrode is disposed below and a second electrode is disposed above.

Referring to FIG. 4, the light emitting diode may be a flip chip light emitting diode in which both the first electrode 25 and the second electrode 26 are disposed on one side. The first electrode 25 and the second electrode 26 may be electrically connected to the submount phase 27.

5 is a cross-sectional view of the filter of FIG. 2, FIG. 6 is a graph measuring reflectivity of each filter of the wavelength band, FIG. 7 is a graph measuring the wavelength width of the light emitted from the light emitting diode and the wavelength of the light passing through the filter. 8 is a graph measuring the wavelength width of the light passing through the band pass filter.

Referring to FIG. 5, the filter 60 may control the wavelength width of the light emitted from the light emitting diodes. The filter 60 may have a structure in which a silicon dioxide optical layer and a titanium dioxide optical layer are alternately stacked. In addition, the filter 60 includes the first optical layer 64, which is either SiOX (1 ≦ X ≦ 3) or MgF ₂ , and TiOx (1 ≦ X ≦ 3), TaOx (1 ≦ X ≦ 3) or ZrO _2. One of the second optical layers 65 may have a structure stacked alternately.

The first optical layer 64 may have a refractive index of 1.4 to 1.5, and the second optical layer 65 may have a refractive index of 2.0 to 3.0.

The filter 60 may include a first reflecting portion 61, a cavity 62, and a second reflecting portion 63 that are sequentially stacked on a substrate.

The first reflecting portion 61 and the second reflecting portion 63 may have a structure in which the first optical layer 64 and the second optical layer 65 including different oxides are stacked in an intersection, and the cavity 62 is disposed. The second optical layer 65 may have a structure in which a plurality of layers are stacked. For example, the first optical layer 64 may be a silicon dioxide optical layer, and the second optical layer 65 may be a titanium dioxide optical layer.

The cavity 62 may have a thickness thicker than the first optical layer 64 or the second optical layer 65. Each of the optical layers may have an optical thickness QWOT corresponding to one quarter of the wavelength of light. According to the exemplary embodiment of the present invention, the first reflector 61 may have a structure in which four silicon dioxide optical layers and three titanium dioxide optical layers are stacked alternately.

The cavity 62 may be a structure provided with four titanium dioxide optical layers. The second reflector 63 may have a structure in which two silicon dioxide optical layers and two titanium dioxide optical layers are laminated in alternating fashion. The cavity 62 is composed only of the titanium dioxide optical layer, and thus may serve to resonate and transmit the light input to the filter 60. As the number of pairs of layers in which the silicon dioxide optical layer and the titanium dioxide optical layer are laminated at the intersection increases, the spectral half width of the light passing through the filter 60 may decrease. As the half width of the spectrum decreases, the wavelength of a specific band can be selectively transmitted.

Light emitted from the light emitting diode may be incident to the second reflector 63 and exit to the substrate 65.

Referring to FIG. 6, it can be seen that the filter is designed to transmit only about 450 nm wavelength band and reflect all remaining wavelength bands in the wavelength band of 350 nm to 500 nm.

Referring to FIG. 7, the spectral half width of the first light B that passes through the filter is smaller than the spectral half width of the second light A that does not pass through the DVB filter.

The half width of the first light B may be 10 nm to 35 nm, and the half width of the second light A may be 2 nm to 10 nm.

For example, the spectral half width of the first light A that does not pass through the filter is 18 nm, and the spectral half width of the second light B that has passed through the DVB filter is 5 nm. Can be. In this case, the light intensity may be reduced by about 5 to 25% compared to before the filtering. However, since the light intensity of a typical blue LED is tens to hundreds of mW, it may not affect optical signal transmission.

The filter can control the half width of the transmitted light spectrum. Thus, the use of a filter can provide light having a wavelength of 440 nm to 460 nm and a half width of 2 to 10 nm.

Referring to FIG. 8, the filter may be manufactured by combining a low band pass filter and a high band pass filter. That is, light of 450 nm or less may be blocked by a high band pass filter and light exceeding 450 nm may be blocked by a low band pass filter so as to transmit only light in the 450 nm wavelength band. Thus, only light having a wavelength band of about 450 nm can pass through the filter.

9 is a conceptual diagram of an optical modulator, FIG. 10 is a view illustrating a state in which an energy band gap is changed by applying a reverse bias, and FIG. 11 is a view illustrating a state in which an absorption wavelength band of the optical modulator is changed by applying a reverse bias. 12 is a graph showing a state in which the intensity of light output from the light emitting device changes as a reverse bias is applied, and FIG. 13 is a conceptual diagram illustrating a process in which an optical signal is modulated by the optical module.

Referring to FIG. 9, the optical modulator 30 may modulate the light (incident light) output from the light emitting diode 20. The structure of the optical modulator 30 is not particularly limited. For example, the optical modulator 30 may be applied to all of the horizontal, vertical, and flip chip structures. Hereinafter, a horizontal structure will be described as an example.

The optical modulator 30 may include a second substrate 31, a second lower semiconductor layer 32, a light absorption layer 33, and a second upper semiconductor layer 34.

The second substrate 31 may be stacked on the carrier substrate. The second substrate 31 may be, for example, a sapphire substrate, a gallium nitride (GaN) substrate, a zinc oxide (ZnO) substrate, a gallium arsenide (GaAs) substrate, a gallium phosphorus (GaP) substrate, or lithium aluminium oxide. It may include one of a (LiAl 2 O 3) substrate, a boron nitride (BN) substrate, an aluminum nitride (AlN) substrate, a plastic substrate, or a glass substrate.

The second lower semiconductor layer 32 may be disposed on the second substrate 31. The second lower semiconductor layer 32 may be an n-type semiconductor layer including a gallium nitride (GaN) -based material. For example, the second lower semiconductor layer 32 may be gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN) or aluminum gallium indium nitride (AlxGayInzN, x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ z ≦ 1).

The second lower semiconductor layer 32 may be formed of a nitride doped with an n-type dopant. The n-type dopant may include silicon (Si), germanium (Ge), tin (Sn), or the like. The second lower semiconductor layer 32 may have a structure in which a first layer doped with an n-type dopant and a second layer not doped with an n-type dopant are alternately stacked.

The second lower semiconductor layer 32 may be grown as a single n-type nitride layer. The third electrode 35 may be formed on an upper surface of the exposed second lower semiconductor layer 32. The third electrode 35 may include a Cr / Au film, a Cr / Ni / Au film, a Ti / Al / Au film, or a Ti / Ni / pt / Au film.

The light absorbing layer 33 may be directly connected to the optical channel to receive the light generated from the light emitting diodes 20. The light absorbing layer 33 may have an energy band gap substantially similar to the active layer of the light emitting diode so as to absorb or transmit light output from the light emitting diode.

The light absorbing layer 33 may cover a portion of the second lower semiconductor layer 32 and may be spaced apart from the third electrode 35. The light absorbing layer 33 may modulate light by an electrical signal provided from the outside (for example, a driving chip).

The light absorption layer 33 may have a multi-quantum well (MQW) structure composed of a plurality of quantum well structures. The light absorption layer 33 may include gallium nitride (GaN) -based material.

The light absorption layer 33 may have a quantum barrier layer and a quantum well layer, and the quantum barrier layer and the quantum well layer of the light absorption layer 33 having a multi-quantum well structure have aluminum x gallium oxides having different x, y, and z composition ratios, respectively. Indium nitride (AlxGayInzN, x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1). In this case, the band gap of the quantum well layer may be smaller than that of the quantum barrier layer, the second lower semiconductor layer 32, and the second upper semiconductor layer 34.

When the light absorbing layer 33 has a Ga polar InGaN quantum well layer / GaN quantum barrier layer structure, the band gap of the light absorbing layer 33 may be adjusted to be equal to the band gap of the light emitting diode at zero bias. However, applying the reverse bias to the optical modulator causes the bandgap of the modulator to be larger than the bandgap of the light emitting diode.

The full width at half maximum of the light spectrum is about 15 to 40 nm in a band gap of 2.0 to 3.0 eV. An external bias should be applied to the optical modulator to cover about 0.5 to 3 times the 15 nm to 40 nm wavelength band. Therefore, the energy band gap of the light absorption layer may be 0.85 times to 1.15 times the energy band gap of the active layer. The energy bandgap of the light absorption layer, which can be adjusted by reverse bias, may be 50 meV to 300 meV.

The second upper semiconductor layer 34 may be disposed on the light absorption layer 33. The second upper semiconductor layer 34 may be a p-type semiconductor layer including a gallium nitride (GaN) -based material. For example, the second upper semiconductor layer 34 may be any one of p-type gallium nitride (GaN), p-type aluminum gallium nitride (AlGaN), and p-type aluminum gallium indium nitride (AlGaInN). In addition, the second upper semiconductor layer 34 is formed by stacking at least two of p-type gallium nitride (GaN), p-type aluminum gallium nitride (AlGaN), and p-type aluminum gallium indium nitride (AlGaInN) at the intersection with each other. It may be a structure.

Referring to FIG. 10A, in the GaN-based semiconductor device, the energy band gap G1 of the quantum well layer and the quantum barrier layer is asymmetrically formed. This is due to the presence of a strong piezoelectric field inside the light absorption layer. Such piezoelectric electric fields can be caused by a variety of causes. For example, the piezoelectric magnetic field may be caused by strain due to lattice constant mismatch.

However, when the reverse bias is applied to the light absorbing layer as shown in FIG. 10B, the energy band G2 may be relatively flat and the band gap may increase (G3).

The wavelength absorbed by the light absorbing layer is determined by the energy band gap. Referring to FIG. 11, in the zero bias, when the first absorption wavelength band 201 is applied and the reverse bias voltage is applied, the absorption wavelength band 202 may be shifted to a shorter wavelength.

Referring to FIG. 12, the intensity of light output from the light emitting device is hardly observed until the reverse bias voltage is applied (203). That is, most of the light output from the light emitting element is absorbed by the light absorbing layer.

However, after the reverse bias voltage is applied, it can be confirmed that the light intensity is increased (204). That is, it can be confirmed that the absorption wavelength band of the light absorption layer is changed by the reverse bias voltage so that the light output from the light emitting device is not absorbed.

Referring to FIG. 13, the optical transmission module 5 may modulate the optical signal L1 using the electrical signal E1. When the electric signal E1 is provided, it may be referred to as a "1 state", and when the electric signal E1 is not provided as an "0 state". The electrical signal E1 may be a reverse bias voltage.

When in the "1 state", the optical transmission module 5 can emit an optical signal L1 (On-state), and when in the "0 state", the optical transmission module 5 emits an optical signal L1. Off-state. Accordingly, the optical transmission module 5 may output a pulsed light signal having a period and emitting (On-state) or not emitting (Off-state) the optical signal L1.

The optical transmission module 5 according to the embodiment may be used for short-range communication.

For example, the optical transmission module 5 may include intelligent transportation system (ITS), visual communication, short distance optical fiber communication, intranet, home networking and wired / wireless IoT. IoT) and the like. The optical transmission module 5 according to the embodiment of the present invention may be used in a data transmission network having a transmission speed of several hundred Mbps to several tens of Gbps in the future.

14 is a conceptual diagram of an optical transmission and reception module according to an embodiment of the present invention, FIG. 15 is a conceptual diagram of an optical transmission module according to an embodiment of the present invention, FIG. 16 is a first modified example of FIG. 15, and FIG. 17. Is a second modified example of FIG. 15, and FIG. 18 is a third modified example of FIG.

Referring to FIG. 14, the light transmitting module may include a light emitting diode 20, a filter 60, a first lens 71, an optical modulator 30, a second lens 72, and a holder disposed in the housing 90. 91).

The area 81 between the light emitting diodes 20 and the filter 60, the area 82 between the filter 60 and the first lens 71, and between the first lens 71 and the light modulator 30. The refractive index adjusting member 80 may be disposed in the region 83.

The refractive index adjusting member 80 may match the refractive index between the light emitting diode 20 and the filter 60, between the filter 60 and the first lens 71, and between the first lens 71 and the light modulator 30. Can be. Thus, the yield of light transmitted from the light emitting diodes to the optical fiber can be increased.

Refractive index adjusting member 80 may be selected from a variety of resins or oils that can match the refractive index.

The first lens 71 may be disposed on the filter 60. The first lens 71 may be convex toward the filter. The first lens 71 may condense the light passing through the filter 60 to the light modulator 30.

In the absence of the first lens 71, the light passing through the filter 60 may be emitted with a wide radiation angle of several tens to 150 degrees. Some of the light having a wide emission angle is not incident to the light modulator 30 may cause light loss. The second lens may serve to condense the modulated light to be effectively incident on the optical fiber.

The ferrule 93 connected with the optical fiber 8 may be fixed to the holder 91. Since the ferrule 93 is connected in a plug and play manner, the ferrule 93 may be optically coupled by an operation of inserting an optical fiber.

The housing 90 may accommodate the light emitting diode 20, the filter 60, the first lens 71, the light modulator 30, the second lens 72, and the holder 91. The housing 90 may include a holder 91 into which the ferrule 93 is inserted.

The holder 91 may be made of a flexible material to facilitate insertion of the ferrule 93 to which the optical fiber is connected.

An antireflection layer 93a may be provided between the second lens 72 and the ferrule 93. The antireflection layer 93a may prevent the light from returning back to the light emitting diode 20. In exemplary embodiments, the anti-reflection layer 93a may include an inclined incident surface. However, the present invention is not limited thereto, and as illustrated in FIG. 15, the antireflection layer 93b may have a structure in which irregular irregularities are continuous.

However, the present invention is not limited thereto, and the position of the filter may vary. For example, referring to FIG. 16, a filter may be disposed between the first lens and the optical modulator. Referring to FIG. 17, the filter may be integrated with an optical modulator formed on the incident light side surface of the optical modulator 30.

19 is a conceptual diagram of an optical receiving module according to an embodiment of the present invention, FIG. 20 is a first modified example of FIG. 19, FIG. 21 is a second modified example of FIG. 19, and FIG. 22 is a third example of FIG. 19. It is a variation example.

Referring to FIG. 19, the vertical light receiving module 6 may include a light receiving element 100, a second lens 72, and a holder 91. The light receiving device 100 may be a diode including a light absorption layer. The second lens 72 may condense the light transmitted through the optical fiber to the light receiving element 100. The housing 90 accommodates the light receiving element 100, the lens 72, and may include a holder 91.

The light receiving element 100 may convert the incident optical signal into an electrical signal by an applied power source. The light receiving device 100 may include a third lower semiconductor layer 130, a photodetection layer 110, and a third upper semiconductor layer 120. The third lower semiconductor layer 130, the photodetection layer 110, and the third upper semiconductor layer 120 may be sequentially stacked on the substrate 140.

The light receiving device 100 may detect light in the visible light region transmitted through the optical transmission path at high speed. The light receiving device 100 may include one of silicon, gallium arsenide, aluminum indium gallium nitride (AlInGaN), indium gallium arsenide (InGaAs), and germanium (Ge).

The substrate 140 may include, for example, a sapphire substrate, a silicon carbide substrate, a gallium nitride (GaN) substrate, a zinc oxide (ZnO) substrate, a gallium arsenide (GaAs) substrate, a gallium phosphorus (GaP) substrate, and lithium aluminium. It may include one of a cerium oxide (LiAl 2 O 3) substrate, a boron nitride (BN) substrate, an aluminum nitride (AlN) substrate, a plastic substrate, or a glass substrate.

The third lower semiconductor layer 130 may be disposed on the substrate 140. The third lower semiconductor layer 130 may be an n-type semiconductor layer including a gallium nitride (GaN) -based material. For example, the third lower semiconductor layer 130 may be gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), or aluminum gallium indium nitride (AlxGayInzN, x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ z ≦ 1).

The third lower semiconductor layer 130 may be formed of a nitride doped with an n-type dopant. The n-type dopant may include silicon (Si), germanium (Ge), tin (Sn), or the like. The third lower semiconductor layer 130 may have a structure in which a first layer doped with an n-type dopant and a second layer not doped with an n-type dopant are alternately stacked. The third lower semiconductor layer 130 may be grown as a single n-type nitride layer.

The photodetection layer 110 may be disposed on the third lower semiconductor layer 130. The photodetection layer 110 may have a multi-quantum well (MQW) structure including a plurality of quantum well structures. The photodetection layer 110 may include a gallium nitride (GaN) -based material.

The photodetection layer 110 may have a quantum barrier layer and a quantum well layer, and the quantum barrier layer and the quantum well layer of the photodetection layer 110 having a multi-quantum well structure have different x, y, z composition ratios, respectively. Aluminum gallium indium nitride (AlxGayInzN, x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1). At this time, the band gap of the quantum well layer should be smaller than the quantum barrier layer, the third lower semiconductor layer 130 and the third upper semiconductor layer 120.

The third upper semiconductor layer 120 may be disposed on the photodetection layer 110. The third upper semiconductor layer 120 may be a p-type semiconductor layer including a gallium nitride (GaN) -based material. For example, the third upper semiconductor layer 120 may be any one of p-type gallium nitride (GaN), p-type aluminum gallium nitride (AlGaN), and p-type aluminum gallium indium nitride (AlGaInN).

The third upper semiconductor layer 120 is a structure in which any two or more of p-type gallium nitride (GaN), p-type aluminum gallium nitride (AlGaN), and p-type aluminum gallium indium nitride (AlGaInN) are stacked on each other. Can be. The sixth electrode 1145 may be disposed on the third upper semiconductor layer 120.

An antireflection layer 93a may be provided between the second lens 72 and the ferrule 93. The antireflection layer 93a may prevent the light from returning back to the light emitting diode 20. In exemplary embodiments, the anti-reflection layer 93a may include an inclined incident surface. However, the present invention is not limited thereto, and the antireflection layer 93b may have a structure in which irregular irregularities are continuous.

The optical receiving module 6 may modulate the provided optical signal into an electrical signal. When providing the optical signal (L2) may be referred to as "On-state", when not providing the optical signal (L2) may be referred to as "Off-state". When in the "On-state", the optical receiving module 6 may output an electrical signal E2 (0 state), and in the "Off-state", the optical receiving module 6 may be an electrical signal E2. May not output (1 state). Accordingly, the light receiving module 6 may output an electric pulse signal wave having a period and outputting the electric signal E2 (1 state) or not (2 state).

An optical filter may be applied to the optical receiver module similarly to the optical transmitter. This is necessary when implementing a multi-wavelength optical reception module. That is, when the optical filter is applied to the incident light side of the light receiving element 100 in the multi-wavelength light receiving module, it is possible to provide good noise characteristics. The optical filter may be all of the above-described filter structure.

In addition, when the bandpass optical filter is mounted to receive only the desired wavelength in front of the optical receiver, only the desired wavelength can be received among the transmitted light, thereby realizing a multiplex optical reception module having multiple wavelengths.

Referring to FIG. 21, the filter 60 may not only be positioned between the second lens 72 and the light receiving element 100, but may be formed on the incident light side of the light receiving element 100 as illustrated in FIG. 22. It is also possible to use a filter integrated with 100). That is, the position of the filter is not particularly limited.

The optical receiving module 6 may be used for short range communication. For example, the optical receiving module 6 may be used for the ITS, visual communication, short distance optical fiber communication, intranet, home networking and IoT. Can be used. The optical receiving module 6 according to the embodiment of the present invention may be used in a data transmission network having a transmission speed of several hundred Mbps to several tens of Gbps in the future.

FIG. 23 is a conceptual diagram of an optical transmission module according to an embodiment of the present disclosure, FIG. 24 is a first modification example of FIG. 23, FIG. 25 is a second modification example of FIG. 23, and FIG. 26 is a third modification of FIG. 23. 27 is a view showing the hollow tube of FIG. 26, FIG. 28 is a fourth modified example of FIG. 23, and FIG. 29 is a graph showing the wavelength width that changes while passing through the filter.

Referring to FIG. 23, the light transmitting module 5A includes a light emitting diode 20, an optical modulator 30 for modulating the first light L11 emitted from the light emitting diode 20, and a light emitting diode 20 and light. The modulator 30 may include an optical member 10 disposed thereon.

The optical member 10 includes a first region 11 in which a light emitting diode 20 is disposed, a second region 12 in which an optical modulator 30 is disposed, and a first region 11 and a second region 12. It may include a third region 13 for optically connecting the. The optical member 10 may be a silicon optical bench (SiOB).

The optical transmission module 5A according to the embodiment may be an integrated circuit chip based on silicon photonics. For example, a light emitting diode, an optical modulator, an optical waveguide, or the like may be integrally implemented in the optical bench. In addition, a light receiving element, a light separator (Y-branch), an optical filter, a grating coupler (edge coupler) for optical coupling with the outside may be additionally implemented.

The light emitting diode 20 may be disposed in the first region 11. The light emitting diodes 20 may be inserted into the first direction. The first direction may be a direction parallel to the thickness direction of the light emitting diode 20 (X direction). Accordingly, the light emitting diode 20 may output light in the first direction.

The light emitting diode 20 may be connected to each of the electrodes 15a and 15b to apply a driving current. The kind of light emitting diode 20 is not particularly limited. Although the horizontal type is illustrated in the drawing, a vertical type and flip chip structure may also be selected. According to the structure of the light emitting diode, the electrode arrangement may be properly adjusted. The light emitting diode 20 may be applied as described above.

The optical modulator 30 may be disposed in the second region 12. The optical modulator 30 may be inserted in the first direction in the same manner as the light emitting diodes 20. Specific configuration of the optical modulator 30 may be applied as described above. The optical modulator 30 may pass light when the reverse bias voltage is applied, and absorb the light at zero bias.

The reflector 16 may be disposed in the third region 13 of the optical member 10. The reflector 16 may reflect the first light output in the first direction in the second direction (Y direction). The second direction is a direction intersecting with the first direction. In exemplary embodiments, the first direction and the second direction may be perpendicular to each other. This structure enables a horizontal light transmission module.

The light L12 may be guided by the optical waveguide 17 provided in the third region 13 and injected into the side of the optical modulator 30. That is, the third region 13 may be an optical channel for injecting light output from the light emitting diodes 20 into the light absorption layer 33 of the light modulator 30.

The light L13 passing through the light absorbing layer may be incident on the external optical fiber 211 and transmitted to the outside. A lens or the like may be further disposed between the optical modulator 30 and the external optical fiber 211 for optical coupling.

Referring to FIG. 24, an inclined surface 17a may be formed in the optical waveguide 17 so that the diameter thereof decreases as the optical waveguide 17 approaches the optical modulator 30. According to such a structure, the phenomenon which light spreads at the end of the optical waveguide 17 can be suppressed.

The optical waveguide 17 may be a bundle waveguide in which a plurality of waveguides are modular. However, the structure of the optical waveguide 17 is not necessarily limited thereto, and a general optical waveguide 18 may be selected as shown in FIG. 25. The optical waveguide may have an inclined surface 18a.

Referring to FIGS. 26 and 27, the third region 13 may include a hollow tube 19 having a tubular shape, and a filter 60 disposed on the hollow tube 19.

Filter 60 may be a low band pass filter, a high band pass filter, and a combination thereof. According to such a structure, the filter 60 can filter only the light of a desired wavelength band.

The hollow tube 19 may have a reflective layer 19a formed therein. The reflective layer 19a may include Al, Ag, or the like having high reflectance, but is not limited thereto. The reflective layer 19a can maintain reflectivity even at low and high temperatures (150 degrees or more), thereby minimizing temperature effects. The material of the reflective layer may be appropriately selected depending on the material of the hollow tube 19.

By way of example, the hollow tube 19 may be a plastic or metal tube. The inner diameter of the hollow tube 19 may be from several tens of um to several mm. The inner diameter of the hollow tube 19 can be appropriately adjusted according to the transmission distance and the use.

Referring to FIG. 28, a plurality of gratings 14 may be formed in the third region 13. The plurality of gratings 14 may control the first light L11 to a desired wavelength. A separate filter 60 may be further disposed between the grating 14 and the optical modulator 30.

Referring to FIG. 29, it can be seen that the spectrum 213 of the light output from the light emitting diode 20 has the largest width and the spectrum 211 of the light passing through the filter 60 has a small false width.

That is, it can be seen that the light output from the light emitting diodes 20 gradually decreases in wavelength and decreases in intensity. According to such a configuration, it is possible to filter only light in a desired wavelength band, so that it can be driven at a relatively low operating voltage.

Claims (20)

1. Light emitting diodes; And

   An optical modulator for modulating the first light emitted from the light emitting diode,

   The light emitting diode and the light modulator include GaN,

   The optical modulator transmits the first light when a voltage is applied.
2. The method of claim 1,

   And the optical modulator passes the first light when a reverse bias voltage is applied.
3. The method of claim 1,

   And the first light is light in a visible light wavelength band.
4. The method of claim 1,

   The light emitting diode and the optical modulator comprises a nitride semiconductor layer.
5. The method of claim 1,

   The light emitting diode,

   A first lower semiconductor layer;

   An active layer disposed on the first lower semiconductor layer; And

   And a first upper semiconductor layer disposed on the active layer.
6. The method of claim 5,

   The optical modulator,

   A second lower semiconductor layer;

   A light absorption layer disposed on the second lower semiconductor layer to absorb light output from the light emitting diode; And

   And a second upper semiconductor layer disposed on the light absorption layer.
7. The method of claim 6,

   And the active layer and the light absorbing layer comprise GaN.
8. The method of claim 6,

   The light absorption layer is an optical transmission module that the energy band gap is increased when the reverse bias voltage is applied.
9. The method of claim 6,

   The light absorbing layer is a light transmitting module, the absorption wavelength band is shorter than the wavelength band of the first light when the reverse bias voltage is applied.
10. The method of claim 1,

    A filter for adjusting a wavelength width of the first light,

    The optical modulator modulates the second light passing through the filter,

    And a half width of the second light is narrower than a half width of the first light.
11. The method of claim 10,

    The full width at half maximum of the first light is 10 to 35nm.
12. The method of claim 10,

    The full width at half maximum of the second light is 2nm to 10nm.
13. The method of claim 10,

    The filter includes a first reflecting portion, a cavity and a second reflecting portion sequentially stacked,

    The first and second reflective parts are laminated with a first optical layer and a second optical layer including different oxides alternately.

    The cavity has a plurality of second optical layers are stacked,

    And the cavity is thicker than the first optical layer or the second optical layer.
14. The method of claim 13,

    And the second optical layer has a higher refractive index than the first optical layer.
15. The method of claim 14,

    The first optical layer has a refractive index of 1.4 to 1.5, the second optical layer has a refractive index of 2.0 to 3.0.
16. The method of claim 14,

    The first optical layer is any one of SiO _X (1 ≦ _X ≦ 3) or MgF ₂ ,

    And the second optical layer is one of TiOx (1 ≦ X ≦ 3), TaOx (1 ≦ X ≦ 3) or ZrO ₂ .
17. The method of claim 1,

    And an active layer of the light emitting diode and a light absorbing layer of the light modulator having the same composition.
18. The method of claim 1,

    And a first lens disposed between the light emitting diode and the optical modulator.
19. The optical transmission module according to claim 1; And

    An optical transceiver comprising an optical receiving module for converting an electrical signal into an optical signal incident from the outside.
20. A plurality of optical transceivers according to claim 19; And

    And an optical fiber connecting the plurality of optical transceivers.

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