JP2005347715A - Surface emission laser, optical unit using it, and optical module using them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface emission laser capable of restraining return light noises and to provide an optical unit using the same. <P>SOLUTION: An optical fiber 30 is connected to the surface emission laser 10 through the intermediary of a lens (not shown in Figure). The surface emission laser 10 is equipped with an opening 18A which is used for extracting laser rays and positioned so as not to rightly confront the light emitting region 13A of a p-side electrode 18. The optical fiber 30 is provided for the surface emission laser 10 so as not to make its core layer 31 located just above the light emission region 13A of the surface emission laser 10, and a monitoring photoelectric conversion device 40 is arranged by the side of the surface emission laser 10. Light LB emitted from the light emitting region 13A is projected at an angle to the normal axis 10B of a mesa part 10A and made to impinge obliquely on the optical fiber 30 or the like. Reflected light R from the lens or the optical fiber 30 is never returned to the surface emission laser 10 and efficiently received by the monitoring photoelectric conversion device 40. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface emitting laser (VCSEL; Vertical Cavity Surface Emitting Laser) and an optical unit including an optical fiber or a photoelectric conversion element for monitoring together with the surface emitting laser. The present invention also relates to an optical module such as a transmission / reception device using the surface emitting laser or the optical unit.

  As a lateral mode control method for a surface emitting laser, for example, Patent Document 1 discloses a configuration in which the output of a fundamental lateral mode is increased by controlling the aperture diameter of an electrode and the aperture diameter of a current confinement portion.

FIG. 10 shows an example of such a conventional surface emitting laser. In the surface emitting laser 110, an n-side multilayer reflective film 112, an active layer 113, a current confinement layer 114, a p-side multilayer reflective film 115, and a p-side contact layer 116 are sequentially stacked on a substrate 111. A p-side electrode 118 is formed on the p-side contact layer 116 via an insulating film 117, and an n-side electrode 119 is formed on the back side of the substrate 111. The opening 118A of the p-side electrode 118 is located immediately above the opening of the current confinement portion 114.
JP 2002-208755 A JP-A-3-222384

  However, in the structure as shown in FIG. 10, the laser beam LB110 from the surface emitting laser 110 was emitted vertically from the light emitting region 113A of the active layer 113 through the opening 118A of the p-side electrode 118. When this surface emitting laser 110 is connected to the optical fiber 130 via a lens (not shown), the reflected light R110 from the end face of the optical fiber 130 or the lens returns straight back to the surface emitting laser 110, and surface emitting is performed. It was easy to be taken into the laser resonator of the laser 110. Therefore, the return light noise is remarkably increased, which may cause the characteristic deterioration of the surface emitting laser 110.

  As a structure in which a surface emitting laser and a monitor photoelectric conversion element such as a photodiode (PD) are combined, for example, Patent Document 2 proposes a structure in which a surface emitting laser is arranged on a monitor photoelectric conversion element. Yes. Here, the back surface reflectance of the surface emitting laser is set to be smaller than 100%, and light emitted from the back surface of the surface emitting laser is incident on the monitor photoelectric conversion element. However, the structure described in Patent Document 2 has a problem in that the threshold current increases because the back surface reflectance is low. Therefore, for example, as shown in FIG. 11, it is conceivable that the reflected light from the optical fiber 130 enters the monitor photoelectric conversion element 140 disposed under the surface emitting laser 110. However, even when the reflected light from the optical fiber 130 is intentionally used for light output monitoring in this way, there is a possibility that a problem due to return light noise occurs as in the configuration of Patent Document 1. Further, the intensity distribution of the reflected light from the optical fiber 130 is strongest in the vicinity of the central axis, but the reflected light having a high intensity is incident on the surface emitting laser 110 and cannot be used for monitoring. There is also a problem that the light receiving efficiency of the light source becomes low.

  The present invention has been made in view of such problems, and a first object thereof is to provide a surface emitting laser capable of suppressing return light noise, an optical unit using the same, and an optical module using these. There is to do.

  A second object of the present invention is to provide a surface emitting laser capable of improving the light receiving efficiency of a monitor photoelectric conversion element, an optical unit using the same, and an optical module using them.

  A surface emitting laser according to the present invention includes a mesa portion having an active layer including a light emitting region, an electrode formed to cover a region facing the light emitting region on the mesa portion, and facing the light emitting region of the electrode. And an opening for taking out light emission provided at a position shifted from the position where the light is emitted. Here, the opening is preferably provided at a position where the 0th-order transverse mode component can be suppressed in the light generated in the light emitting region.

  An optical unit according to the present invention includes the above-described surface-emitting laser according to the present invention and an optical fiber having a core layer that transmits light from the surface-emitting laser. It is arranged with respect to the surface emitting laser so as to avoid the light emitting region. Here, the optical fiber is preferably disposed with respect to the surface emitting laser so that the central axis is parallel to the vertical axis of the mesa portion of the surface emitting laser. Further, it is preferable that a monitor photoelectric conversion element for controlling the light output of the surface emitting laser is provided, and the monitor photoelectric conversion element is disposed beside the surface emitting laser.

  A first optical module according to the present invention includes the surface emitting laser according to the present invention. A second optical module according to the present invention includes the optical unit according to the present invention.

  According to the surface emitting laser of the present invention or the first optical module of the present invention, the opening for extracting light emission is provided at a position shifted from the position facing the light emitting area, and thus generated in the light emitting area. Light can be emitted obliquely with respect to the vertical axis of the mesa portion, and reflected light from an external lens or optical fiber can be made difficult to enter the surface emitting laser. Therefore, the return light noise can be suppressed, and the characteristic deterioration of the surface emitting laser can be prevented.

  In particular, if the opening is provided at a position where the 0th order transverse mode component can be suppressed in the light generated in the light emitting region, the 0th order transverse mode component emitted vertically (90 °) from the light emitting region can be suppressed. Therefore, it is possible to suppress the reflected light from an external lens or optical fiber from entering the surface emitting laser perpendicularly and entering the inside. Therefore, an increase in the return light noise can be surely prevented.

  According to the optical unit of the present invention or the second optical module of the present invention, the optical fiber is arranged with respect to the surface emitting laser so that the core layer avoids the light emitting region of the surface emitting laser. The light emitted obliquely from the surface emitting laser can be easily incident on the optical fiber, and the light reflected from the end of the optical fiber is not returned to the surface emitting laser by causing the light from the surface emitting laser to enter the optical fiber obliquely. Can be. Therefore, the return light noise can be suppressed, and the characteristic deterioration of the surface emitting laser can be prevented. In particular, in the case of butt coupling in which a surface emitting laser and an optical fiber are directly connected without using a lens, reflected light returns to the surface emitting laser even if the distance between the surface emitting laser and the optical fiber is reduced. Therefore, return light noise can be effectively suppressed.

  In particular, if a monitor photoelectric conversion element for controlling the light output of the surface emitting laser is arranged beside the surface emitting laser, the reflected light from the optical fiber is received by the monitor photoelectric conversion element and used for light output monitoring. And the light receiving efficiency of the monitor photoelectric conversion element can be increased.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Surface emitting laser)
FIG. 1 shows a cross-sectional configuration of a surface emitting laser according to an embodiment of the present invention. The surface-emitting laser 10 is used for a transmission / reception device in optical fiber communication, for example, and has an n-side multilayer reflective film 12 made of an n-type semiconductor multilayer film and an active layer 13 having a light-emitting region 13A on a substrate 11. , A current confinement layer 14, a p-side multilayer reflective film 15 made of a p-type semiconductor multilayer film, and a p-side contact layer 16 are sequentially stacked. Further, the p-side contact layer 16, the p-side multilayer reflective film 15, the current confinement layer 14, the active layer 13, and a part of the n-side multilayer reflective film 12 are substantially columnar mesa portions 10A. The surface emitting laser 10 is about 300 μm square, for example, and the diameter φ _10A of the mesa portion _10A is about 30 μm to 40 μm, for example.

The substrate 11 has, for example, a thickness in the stacking direction (hereinafter simply referred to as “thickness”) of about 150 nm, and an n-type gallium arsenide (n-type impurity such as silicon (Si) or selenium (Se)) is added. GaAs). The n-side multilayer reflective film 12 includes, for example, n-type Al _0.9 Ga _0.1 As mixed crystal layers and n-type Al _0.1 Ga _0.9 As layers to which n-type impurities such as silicon (Si) or selenium (Se) are added alternately. This is a DBR (Distributed Bragg Reflector) mirror having a laminated structure.

The active layer 13 has, for example, a thickness of about 30 nm to 50 nm and is made of GaAs not added with impurities. The light emitting region 13 </ b> A is located in the center of the active layer 13. The light emitting region 13A preferably has a diameter φ _13A of, for example, 5 μm or more in order to be able to oscillate in the transverse multimode.

The current confinement layer 14 is for limiting the light emitting region 13A of the active layer 13, and for example, an insulating layer containing aluminum (Al) around the low resistance region 14A made of aluminum arsenic (AlAs) or AlGaAs mixed crystal. An annular high resistance region 14B made of a conductive oxide (AlO _x , AlGaO _x ) is provided, and the current is confined only to the low resistance region 14A. A region corresponding to the low resistance region 14 </ b> A of the active layer 13 is a light emitting region 13.

The p-side multilayer reflective film 15 includes, for example, p-type Al _0.9 Ga _0.1 As mixed crystal layers and p-type Al _0.1 Ga _0.9 As layers to which p-type impurities such as zinc (Zn) or carbon (C) are added alternately. This is a DBR mirror having a laminated structure. The p-side contact layer 16 is made of, for example, p-type GaAs to which a p-type impurity such as zinc (Zn) or carbon (C) is added at a high concentration.

A p-side electrode 18 is formed on the surface of the mesa portion 10A with an insulating film 17 made of, for example, silicon oxide (SiO _x ) interposed therebetween. The p-side electrode 18 is provided with an opening 18A for extracting light emission. The p-side electrode 18 is made of, for example, titanium (Ti) / platinum (Pt) / gold (Au) in order from the side closer to the p-side contact layer 16, and the p-side contact is made through an opening provided in the insulating film 17. Electrically connected to layer 16. On the other hand, an n-side electrode 19 is formed on the back side of the substrate 11. The n-side electrode 19 is composed of, for example, gold germanium (AuGe) / nickel (Ni) / gold (Au) in order from the side closer to the substrate 11.

  As shown in FIG. 2, the p-side electrode 18 is formed so as to cover a region facing the light emitting region 13A of the mesa portion 10A, and the opening 18A faces the light emitting region 13A of the p-side electrode 18. It is provided at a position shifted from the position. Thereby, in this surface emitting laser 10, the light LB generated in the light emitting region 13A can be emitted obliquely at an angle θ with respect to the vertical axis 10B of the mesa portion 10A, and the reflected light from an external lens or optical fiber Can be prevented from entering the inside of the surface emitting laser 10. The shape of the opening 18A is not limited to the circular shape shown in FIG. 2, and the diameter is not particularly limited.

  Since the opening 18A is provided at a position shifted from the position opposed to the light emitting region 13A, the surface emitting laser 10 can control the transverse mode of the light LB generated in the light emitting region 13A. Yes. That is, as shown in FIG. 3, the lateral mode component desired to be extracted from the light LB generated in the light emitting region 13A is selectively extracted to the outside through the opening 18A, while the other lateral mode components are extracted from the p-side electrode. It can be suppressed by reflecting by 18.

  The opening 18A is preferably provided at a position where the 0th-order transverse mode component can be suppressed in the light LB generated in the light emitting region 13A. Since the zeroth-order transverse mode component is emitted vertically (90 °) from the light emitting region 13A, reflected light from an external lens or optical fiber is likely to enter the surface emitting laser 10 perpendicularly and easily enter the inside, and return light noise. It is because there exists a possibility of increasing. Even when the 0th-order transverse mode component is reflected by the p-side electrode 18 in this way, the surface-emitting laser 10 is originally provided with a reflective film such as the p-side multilayer reflective film 15. There is no adverse effect from the reflected zeroth-order transverse mode component.

  FIG. 4 schematically shows an example of the transverse mode obtained when the diameter of the light emitting region 13A of the surface emitting laser 10 is about 10 nm and the diameter of the opening 18A is 10 μm to 15 μm. The light LB generated in the light emitting region 13A is, for example, a zero-order transverse mode component that is emitted vertically from the vicinity of the center of the light emitting region 13A (half-value width is, for example, about 15 °), and a position that is off from the vicinity of the center of the light emitting region 13A It is a mixture of primary and secondary higher order transverse mode components radiated at a wide angle.

  FIG. 5 shows an example of the transverse mode control by the position of the opening 18A in the surface emitting laser 10 having the transverse mode as shown in FIG. FIG. 5 shows only the secondary transverse mode component LB2 among the high-order transverse mode components. As shown in FIG. 5A, in the conventional structure in which the opening 18A is provided at a position facing the light emitting region 13A, the zeroth-order transverse mode component LB0 and the second-order transverse mode component LB2 can be extracted from the opening 18A. it can. As shown in FIG. 5B, when the opening 18A is provided at a position shifted from the position facing the light emitting region 13A and the end of the opening 18A is aligned with the vertical axis 10B of the mesa portion 10A, the zeroth-order horizontal The mode component LB0 can be partially suppressed. As shown in FIG. 5C, if the opening 18A is further provided at a position closer to the periphery of the mesa portion 10A (a displacement amount d of the opening 18A from the vertical axis 10B), the zero-order transverse mode component LB0 is obtained. It is possible to suppress completely and only the secondary transverse mode component LB2 can be selectively extracted from the opening 18A.

  Moreover, it is preferable that the opening 18A is provided at a position where at least part of the first-order or higher-order transverse mode component of the light LB generated in the light emitting region 13A can be selectively extracted. This is because the high-order transverse mode component does not exit perpendicularly (90 °) from the light emitting region 13A, so that the reflected light from an external lens or optical fiber is difficult to enter the surface emitting laser 10.

  Note that, when the 0th-order transverse mode component is suppressed and the first-order or higher-order transverse mode component is used as described above, the light output is smaller than when the light LB including the 0th-order transverse mode component is used. May be slightly smaller. However, surface-emitting lasers are generally very sensitive to return light, and high-speed modulation becomes difficult. Therefore, even if the light output is somewhat reduced by suppressing the zeroth-order transverse mode component, the return light is suppressed. Therefore, it is advantageous to obtain advantages such as improved reliability and expanded application range. Even when the zeroth-order transverse mode component is suppressed, if the injection current is increased, a higher-order transverse mode is likely to occur and the light output increases, so that there is no shortage of light for normal use. Output can be secured.

  Furthermore, it is more preferable that the opening 18A is provided at a position where light is emitted with the strongest intensity among the light emission positions of the high-order transverse mode component in the light emission region 13A (hereinafter referred to as “maximum light emission position”). This is because a larger light output can be obtained. In addition, as shown in FIG. 6, a plurality of openings 18A are provided corresponding to the light emission positions of the higher-order transverse mode components, or an annular opening 18A is provided as shown in FIG. More preferred. This is because it is possible to select and use light of a mode in which the light intensity is highest at a desired operating current among the high-order transverse modes. In this case, the size of the opening 18A is such that a sufficient contact area between the p-side electrode 18 and the p-side contact layer 16 can be secured and the contact resistance can be suppressed within an appropriate range. desirable.

  The surface emitting laser 10 can be manufactured, for example, as follows.

  First, for example, the substrate 11 made of the above-described thickness and material is prepared, and the n-side multilayer reflective film 12 is formed on the front side of the substrate 11 by, for example, MOCVD (Metal Organic Chemical Vapor Deposition) method. , An active layer 13, an unoxidized layer (not shown) for forming the current confinement layer 14, a p-side multilayer reflective film 15 and a p-side contact layer 16 are grown in this order.

Next, a mask (not shown) made of a resist is formed on the p-side contact layer 16, and the p-side contact layer 16, the p-side multilayer reflective film 15, an unoxidized layer (not shown), the active layer 13 and the like are etched by using the mask. by selectively removing the n-side multilayer reflective film 12, to form a substantially cylindrical mesa portion 10A having a diameter phi _10A described above. Subsequently, a mask (not shown) is removed.

  After that, for example, by heating in water vapor, an unoxidized layer (not shown) exposed on the side surface of the mesa portion 10 is annularly oxidized from the periphery toward the center, thereby having the low resistance region 14A and the high resistance region 14B. A current confinement layer 14 is formed.

  After forming the current confinement layer 14, the insulating film 17 made of the above-described material is formed over the entire surface of the substrate 11 by, for example, vapor deposition. After forming the insulating film 17, an n-side electrode 19 is formed on the back side of the substrate 11.

  After the n-side electrode 19 is formed, the insulating film 17 is selectively removed by, for example, photolithography and etching, and an opening is provided on the p-side contact layer 16. After providing an opening in the insulating film 17, a p-side electrode 18 is formed on the mesa portion 10A. After the p-side electrode 18 is formed, the p-side electrode 18 is selectively removed by, for example, photolithography and etching. Thus, the region facing the light emitting region 13A on the mesa portion 10A is covered with the p-side electrode 18, and the opening 18A is provided at a position shifted from the position facing the light emitting region 13A of the p-side electrode 18. Thus, the surface emitting laser 10 shown in FIG. 1 is completed.

  In this surface emitting laser 10, when a predetermined voltage is applied between the n-side electrode 19 and the p-side electrode 18, the drive current supplied from the p-side electrode 18 is current-confined by the current confinement layer 14. Light is emitted by being injected into the active layer 13 and electron-hole recombination. This light is reflected by the n-side multilayer reflective film 12 and the p-side multilayer reflective film 15, reciprocates between them to generate laser oscillation, and is emitted to the outside from the opening 18 A of the p-side electrode 18 as a laser beam. Here, since the opening 18A is provided at a position shifted from the position facing the light emitting region 13A of the p-side electrode 18, the light LB generated in the light emitting region 13A is relative to the vertical axis 10B of the mesa portion 10A. The reflected light from the external lens or optical fiber is less likely to enter the surface emitting laser 10. Therefore, the return light noise is suppressed and the characteristic deterioration of the surface emitting laser 10 is prevented.

(Optical unit)
FIG. 8 shows a configuration of the optical unit 20 including the surface emitting laser 10. This optical unit is used, for example, in a transmission unit in a transmission / reception device, and an optical fiber 30 is connected to the surface emitting laser 10 via a lens (not shown).

The optical fiber 30 has a core layer 31 that transmits light LB from the surface emitting laser 10, and a cladding layer 32 for confining light around the core layer 31 is provided. The diameter φ ₃₀ of the optical fiber 30 is, for example, 200 μm, and the diameter φ ₃₁ of the core layer ₃₁ is, for example, 50 μm. Note that the diameter of a lens (not shown) is, for example, about 200 μm.

  The optical fiber 30 is disposed with respect to the surface emitting laser 10 so that the core layer 31 avoids the light emitting region 13 </ b> A of the surface emitting laser 10. Thereby, in this optical unit 20, the light LB emitted obliquely from the surface emitting laser 10 is easily incident on the optical fiber 30, and the light LB from the surface emitting laser 10 is incident on the optical fiber 30 obliquely. Reflected light from the optical fiber 30 or a lens (not shown) can be prevented from returning to the surface emitting laser 10.

  The optical fiber 30 is arranged with respect to the surface emitting laser 10 so that the central axis 30B is parallel to the vertical axis 10B of the mesa portion 10A of the surface emitting laser 10. Thereby, in this optical unit 20, the position of the optical fiber 30 and the surface emitting laser 10 in the optical axis direction can be matched with high accuracy, and the reflected light R from the fiber 30 or a lens (not shown) is applied to the surface emitting laser 10. It is possible to reliably prevent it from returning. On the other hand, conventionally, in order to make light from the surface emitting laser incident on the optical fiber obliquely, the surface emitting laser is disposed obliquely with respect to the optical fiber, or the end face of the optical fiber is processed obliquely. Although the mounting process is complicated, it is difficult to adjust the angle of tilting the surface emitting laser and the processing angle of the optical fiber, and the optical fiber and the surface emitting laser must be aligned with high accuracy. It was difficult.

  The core layer 31 of the optical fiber 30 may be disposed anywhere as long as a part of the core layer 31 is not on the light emitting region 13A, and the position of the opening 18A of the surface emitting laser 10 and the emission direction of the light LB. It is desirable to select an optimal position based on the above.

  Further, the optical unit 20 includes a monitor photoelectric conversion element 40 such as a photodiode in order to control the light output of the surface emitting laser 10. The monitor photoelectric conversion element 40 is disposed beside the surface emitting laser 10. Thereby, in this optical unit, the reflected light R from the optical fiber 30 or a lens (not shown) is received by the monitor photoelectric conversion element 40 so that the light receiving efficiency is improved and the light output can be monitored efficiently. .

  In this optical unit 20, the light LB generated in the light emitting region 13A of the surface emitting laser 10 is emitted to the outside from the opening 18A of the p-side electrode 18, passes through a lens (not shown), or the core layer 31 of the optical fiber 30 or The light enters the clad layer 32. The light incident on the core layer 31 enters the core layer 31 as it is, but a part of the light is reflected on the end face of the core layer 31. The light incident on the clad layer 32 is reflected on the end face of the clad layer 32. The reflected light R is received by the monitor photoelectric conversion element 40 and used for light output monitoring. Here, the opening 18 </ b> A of the surface emitting laser 10 is provided at a position shifted from the position facing the light emitting region 13 </ b> A of the p-side electrode 18, and the optical fiber 30 is the core layer 31 and the light emitting region of the surface emitting laser 10. Since the monitor photoelectric conversion element 40 is disposed beside the surface emitting laser 10 so as to avoid the surface 13A, the light LB generated in the light emitting region 13A is generated by the mesa unit 10A. The light is emitted obliquely with respect to the vertical axis 10B of the optical fiber 30 and is incident obliquely on the optical fiber 30 or the like. Therefore, the reflected light R from the lens (not shown) or the optical fiber 30 does not return to the surface emitting laser 10 but is received by the monitor photoelectric conversion element 40. Therefore, the return light noise of the surface emitting laser 10 is suppressed, and the light receiving efficiency of the monitor photoelectric conversion element 40 is improved.

(Optical module)
FIG. 9 schematically shows a configuration of an optical module including the optical unit 20 having such a surface emitting laser 10. The optical module 200 is used as an FEM (front end module) that converts an optical signal and an electrical signal in a high-speed optical communication system, and includes a transmission unit 210 and a reception unit 220 on a base body 201. Yes.

  The transmission unit 210 includes, for example, the optical unit 20 described above and a driver 211 that drives the surface emitting laser 10. As the driver 211, a known driver IC (Integrated Circuit) can be used.

  The receiving unit 220 is a general unit including, for example, a photoelectric conversion element (photodiode) 221 and an amplifier 222 such as a TIA (transimpedance amplifier) or LIA (limiting impedance amplifier). An optical fiber 223 is connected to the receiving unit 220 via a connector (not shown).

  In the optical module 200, the surface emitting laser 10 is driven by the driver 211 based on the electric signal S1 supplied from the outside in the transmission unit 210, and the optical signal P1 is transmitted through the optical fiber 30, and the monitor photoelectric module The light output of the surface emitting laser 10 is controlled by the conversion element 40. In the receiving unit 220, the optical signal P2 supplied via the optical fiber 223 is incident on the photoelectric conversion element 221 and converted into an electric signal. The electric signal is amplified by the amplifier 222, and necessary conversion processing is performed. And output to the outside as an electric signal S2. Here, since the optical module 200 includes the optical unit 20 having the surface emitting laser 10 of the present embodiment, the return light noise of the surface emitting laser 10 is suppressed, and the characteristic deterioration of the surface emitting laser 10 hardly occurs. It has become. Therefore, the reliability of the optical unit 20 and the optical module 200 having the surface emitting laser 10 is improved.

  As described above, in the surface emitting laser 10 according to the present embodiment, the opening 18A is provided at a position shifted from the position facing the light emitting region 13A of the p-side electrode 18, and thus the light LB generated in the light emitting region 13A. Can be emitted obliquely with respect to the vertical axis 10 </ b> B of the mesa unit 10 </ b> A, and reflected light from an external lens or the optical fiber 30 can be made difficult to enter the inside of the surface emitting laser 10. Therefore, return light noise can be suppressed and characteristic deterioration of the surface emitting laser 10 can be prevented.

  In particular, if the opening 18A is provided at a position where the 0th-order transverse mode component can be suppressed in the light LB generated in the light emitting region 13A, the 0th order transverse mode emitted vertically (90 °) from the light emitting region 13A. The component can be suppressed, and the reflected light from the external lens or the optical fiber 30 can be prevented from entering the surface emitting laser 10 perpendicularly and entering the inside. Therefore, an increase in the return light noise can be surely prevented.

  In the optical unit 20 of the present embodiment, the optical fiber 30 is arranged with respect to the surface emitting laser 10 so that the core layer 31 avoids the light emitting region 13A of the surface emitting laser 10, so that the surface emitting laser is used. The light LB emitted obliquely from 10 is easily incident on the optical fiber 30 and the light LB from the surface emitting laser 10 is incident obliquely on the optical fiber 30 so that the reflected light R from the optical fiber 30 is reflected by the surface emitting laser 10. It is possible not to return to. Therefore, return light noise can be suppressed and characteristic deterioration of the surface emitting laser 10 can be prevented. In particular, in the case of butt coupling in which the surface emitting laser 10 and the optical fiber 30 are directly connected without using a lens, the reflected light R is generated even if the distance between the surface emitting laser 10 and the optical fiber 30 is reduced. Returning light noise can be effectively suppressed without returning to 10.

  In particular, if the monitor photoelectric conversion element 40 for controlling the light output of the surface emitting laser 10 is arranged beside the surface emitting laser 10, the reflected light R from the optical fiber 30 or the like is received by the monitor photoelectric conversion element 40. It can be used for light output monitoring, and the light receiving efficiency of the monitor photoelectric conversion element 40 can be increased.

  Since the optical module 200 of the present embodiment includes the optical unit 20 having the surface emitting laser 10 of the present embodiment, the optical module 200 with high reliability can be realized.

  While the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment, and various modifications can be made. For example, the material and thickness of each layer described in the above embodiment, the film formation method, the film formation conditions, and the like are not limited, and may be other materials and thicknesses, or other film formation methods and Film forming conditions may be used.

  Moreover, in the said embodiment and Example, although the structure of the surface emitting laser 10 was specifically mentioned and demonstrated, it is not necessary to provide all the layers, and also provided with other layers, such as a light guide layer. Also good.

  The surface emitting laser and the optical unit according to the present invention are applicable to optical fiber communication, optical wiring, optical space transmission, and the like. The optical module according to the present invention can be used for an optical transceiver.

It is sectional drawing showing the structure of the surface emitting laser which concerns on one embodiment of this invention. It is a top view of the p side electrode and opening part which were shown in FIG. It is a perspective view for demonstrating control of the transverse mode by the p side electrode and opening part shown in FIG. It is a table | surface showing an example of the transverse mode obtained with the surface emitting laser shown in FIG. FIG. 5 is a cross-sectional view for explaining control of the transverse mode depending on the position of the opening in the surface emitting laser having the transverse mode shown in FIG. 4. It is a top view showing the modification of the p side electrode and opening part which were shown in FIG. FIG. 10 is a plan view illustrating another modification of the p-side electrode and the opening illustrated in FIG. 2. It is sectional drawing showing the structure of the optical unit which has a surface emitting laser shown in FIG. It is a block diagram showing the structure of the optical module provided with the optical unit shown in FIG. It is sectional drawing for demonstrating the problem of the conventional surface emitting laser. It is sectional drawing for demonstrating the problem of the arrangement | positioning relationship between the conventional surface emitting laser and a monitor photoelectric conversion element.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Surface emitting laser, 10A ... Mesa part, 10B ... Vertical axis, 11 ... Substrate, 12 ... N side multilayer reflective film, 13 ... Active layer, 13A ... Light emitting region, 14 ... Current confinement layer, 14A ... Low resistance region, 14B ... High resistance region, 15 ... p-side multilayer reflective film, 16 ... p-side contact layer, 17 ... insulating film, 18 ... p-side electrode, 18A ... opening, 19 ... n-side electrode, 20 ... optical unit, 30 ... Optical fiber, 30B ... center axis, 31 ... core layer, 32 ... clad layer, 40 ... monitor photoelectric conversion element (PD), 200 ... optical module

Claims (14)

A mesa portion having an active layer including a light emitting region;
An electrode formed so as to cover a region facing the light emitting region on the mesa unit;
A surface emitting laser comprising: an opening for extracting light emission provided at a position shifted from a position facing the light emitting region of the electrode. The surface emitting laser according to claim 1, wherein the opening is provided at a position capable of suppressing a zeroth-order transverse mode component of light generated in the light emitting region. 2. The surface according to claim 1, wherein the opening is provided at a position where at least a part of a first-order or higher-order transverse mode component of light generated in the light emitting region can be selectively extracted. Light emitting laser. The mesa portion includes a current confinement layer for limiting a light emitting region of the active layer, and the current confinement layer is formed of a semiconductor with a low resistance region and an insulating oxide around the low resistance region. The surface emitting laser according to claim 1, further comprising an annular high resistance region. The surface emitting laser according to claim 1, wherein the light emitting region has a diameter of 5 μm or more. An optical unit comprising a surface emitting laser and an optical fiber having a core layer that transmits light from the surface emitting laser,
The surface emitting laser includes a mesa portion having an active layer including a light emitting region, an electrode formed to cover a region facing the light emitting region on the mesa portion, and a position of the electrode facing the light emitting region. An opening for taking out light emission provided at a position deviated from,
The optical unit, wherein the optical fiber is disposed with respect to the surface emitting laser so that the core layer avoids a light emitting region of the surface emitting laser. The optical unit according to claim 6, wherein the optical fiber is disposed with respect to the surface emitting laser so that a central axis is parallel to a vertical axis of a mesa portion of the surface emitting laser. The optical unit according to claim 6, further comprising a monitor photoelectric conversion element for controlling an optical output of the surface emitting laser, wherein the monitor photoelectric conversion element is disposed beside the surface emitting laser. The optical unit according to claim 6, wherein the opening is provided at a position capable of suppressing a zeroth-order transverse mode component in the light generated in the light emitting region. The optical device according to claim 6, wherein the opening is provided at a position where at least a part of a first-order or higher-order transverse mode component in the light generated in the light emitting region can be selectively extracted. unit. The optical unit according to claim 6, wherein the light emitting region has a diameter of 5 μm or more. An optical module having a surface emitting laser,
The surface emitting laser is
A mesa portion having an active layer including a light emitting region;
An electrode formed so as to cover a region facing the light emitting region on the mesa unit;
An optical module comprising: an opening for extracting light emission provided at a position shifted from a position facing the light emitting region of the electrode. An optical module comprising an optical unit comprising a surface emitting laser and an optical fiber having a core layer that transmits light from the surface emitting laser,
The surface emitting laser includes a mesa portion having an active layer including a light emitting region, an electrode formed to cover a region facing the light emitting region on the mesa portion, and a position of the electrode facing the light emitting region. An opening for taking out light emission provided at a position deviated from,
The optical module, wherein the optical fiber is arranged with respect to the surface emitting laser so that the core layer avoids a light emitting region of the surface emitting laser. The optical module according to claim 13, further comprising a monitor photoelectric conversion element for controlling an optical output of the surface emitting laser, wherein the monitor photoelectric conversion element is disposed beside the surface emitting laser.

Images