JP2013058563A - Surface emission laser module - Google Patents

Abstract

A surface-emitting laser module capable of high-speed operation is provided.
The surface emitting laser chip includes a surface emitting laser chip having a surface emitting laser that emits light in a direction perpendicular to a semiconductor substrate surface, and a dielectric substrate connected to a side surface of the surface emitting laser chip. In the laser chip, a signal electrode is formed on one surface from which the light is emitted, and a back surface ground electrode is formed on the other surface opposite to the surface on which the signal electrode is formed, A surface light emission characterized in that a signal transmission line connected to the signal electrode is formed on one surface of the dielectric substrate, and the signal electrode and the signal transmission line are connected to each other. The above problem is solved by providing a laser module.
[Selection] Figure 3

Description

  The present invention relates to a surface emitting laser module.

  A vertical cavity surface emitting laser (VCSEL) is a semiconductor laser that emits light in a direction perpendicular to the substrate. It is lower in cost and higher performance than an edge emitting laser, and can be easily arrayed. It has the characteristic that it is. For this reason, studies have been made on light sources for optical communication such as optical interconnection, light sources for optical pickups, light sources for image forming apparatuses such as laser printers, and the like.

  Specifically, the surface-emitting laser has characteristics such as a low threshold and low power consumption, and optically, since the beam diameter of the emitted light is circular, it can be easily coupled with an optical fiber. In addition, since the mode volume in the resonator is small, modulation of several tens of GHz is possible, and some semiconductor lasers for communication have been put to practical use. In addition, since the two-dimensionalization is easy due to the structural features of the surface emitting laser, development of array elements in which several tens of channels are integrated has been actively conducted.

  Surface emitting lasers with these characteristics are not only used for light transmission light sources such as LAN (Local Area Network), but also for light transmission between boards, between boards, between LSI (Large Scale Integration) chips, and within chips. Application to a light source for an image forming apparatus, and further to a light source for an image forming apparatus is expected.

In a high-speed and high-speed communication module, in order to modulate a semiconductor laser at high speed, it is necessary to employ a mounting method that reduces parasitic capacitance and parasitic inductance as much as possible and an electric communication circuit that can match impedance with a modulation signal source. is there. The cut-off frequency f _c (cutoff frequency), which is an index of the modulation band of the semiconductor laser, is expressed by the equation shown in Equation 1, C is the capacitance of the element, and R is the resistance.

従って、半導体レーザの容量を低減すれば、高速応答が可能になる。半導体レーザの容量とは、半導体レーザ自身の容量Ｃ_０と、寄生成分の配線を含むボンディングパッドの容量Ｃ_ａとの和（Ｃ_０＋Ｃ_ａ）により表わされる。従来の半導体レーザの実装方法では、ボンディングパッドが必要であり、素子容量低減には限界があった。

Therefore, if the capacity of the semiconductor laser is reduced, a high-speed response is possible. The capacity of the semiconductor laser, the capacitance C ₀ of the semiconductor laser itself, represented by the sum of the capacitance C _a of the bonding pads including the wiring parasitics (C 0 _{+ C a).} The conventional semiconductor laser mounting method requires a bonding pad, and there is a limit to reducing the element capacitance.

  For this reason, in the surface emitting semiconductor laser element described in Patent Document 1, the electrode capacitance in the VCSEL is a coplanar line, thereby reducing the wiring capacitance and improving the high frequency characteristics.

  However, in the surface-emitting type semiconductor laser device described in Patent Document 1, the electrode pad of the surface-emitting laser and the transmission line of the submount are connected by a bonding wire made of gold. Since the bonding wire made of gold becomes an inductance component in a high frequency region, there is a problem in that mismatch of characteristic impedance occurs and the high frequency characteristic is deteriorated.

  The present invention has been made in view of the above, and an object of the present invention is to provide a surface emitting laser module excellent in high speed and high frequency characteristics.

  The present invention includes a surface emitting laser chip having a surface emitting laser that emits light in a direction perpendicular to a semiconductor substrate surface, and a dielectric substrate connected to a side surface of the surface emitting laser chip, the surface emitting In the laser chip, a signal electrode is formed on one surface from which the light is emitted, and a back surface ground electrode is formed on the other surface opposite to the surface on which the signal electrode is formed, A signal transmission line connected to the signal electrode is formed on one surface of the dielectric substrate, and the signal electrode and the signal transmission line are connected to each other.

  According to the present invention, a surface emitting laser module excellent in high speed and high frequency characteristics can be provided.

Structure diagram of surface emitting laser element in first embodiment Structural drawing of the main part of the surface emitting laser element in the first embodiment Explanatory drawing of the surface emitting laser chip in the first embodiment Explanatory drawing of the surface emitting laser module in 1st Embodiment Explanatory drawing of the surface emitting laser chip in 2nd Embodiment Explanatory drawing of the surface emitting laser module in 2nd Embodiment Explanatory drawing of the surface emitting laser module in 3rd Embodiment Explanatory drawing of the surface emitting laser module in 4th Embodiment Configuration diagram of laser printer in fifth embodiment Configuration of Optical Scanning Device in Fifth Embodiment Configuration diagram of color printer according to sixth embodiment

  The form for implementing this invention is demonstrated below. In addition, about the same member etc., the same code | symbol is attached | subjected and description is abbreviate | omitted.

[First Embodiment]
(Surface emitting laser)
First, a surface emitting laser element used in the surface emitting laser module according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, the surface-emitting laser element 100 is a surface-emitting laser having an oscillation wavelength of 780 nm, and has a buffer layer 102, a lower semiconductor DBR 103, a lower spacer layer 104, an active layer on one surface of a GaAs substrate 101. A layer 105, an upper spacer layer 106, an upper semiconductor DBR 107, a contact layer 109, and the like are formed, an insulating film 111 is formed, and an anode electrode 113 is formed. A cathode electrode 114 is formed on the other surface of the GaAs substrate 101.

The lower semiconductor DBR 103 is stacked on the + Z side of the buffer layer 102. As shown in FIG. 2, the lower semiconductor DBR 103 is made of a low refractive index layer 103a made of n-AlAs and n-Al _0.3 Ga _0.7 As. It is formed by alternately stacking 40.5 pairs of high refractive index layers 103b. Between each refractive index layer, a composition gradient layer having a thickness of 20 nm is formed by gradually changing the composition from one composition to the other composition in order to reduce electric resistance. Each of the low refractive index layer 103a and the high refractive index layer 103b is formed so as to have an optical film thickness of λ / 4, including 1/2 of the film thickness of the adjacent composition gradient layer. Incidentally, when the optical thickness is λ / 4, the actual film thickness D in the layer is D = λ / 4n. Here, the wavelength λ is the oscillation wavelength in the surface emitting laser element, and n is the refractive index of the medium of the layer.

The lower spacer layer 104 is stacked on the + Z side of the lower semiconductor DBR 103, a layer made of non-doped _{(Al 0.1 Ga 0.9) 0.5 In} 0.5 P.

  The active layer 105 is laminated on the + Z side of the lower spacer layer 104. As shown in FIG. 2, the quantum well layers 105a and the barrier layers 105b are alternately formed, and the three quantum well layers 105a are formed. And the four barrier layers 105b form a triple quantum well structure. The quantum well layer 105a is formed of GaInAsP, which has a composition that induces a 0.7% compressive strain, and the wavelength in the band gap is about 780 nm. The barrier layer 105b is formed of GaInP that has a composition that induces a tensile strain of 0.6%.

The upper spacer layer 106 is stacked on the + Z side of the active layer 105 is formed of non-doped _{(Al 0.1 Ga 0.9) 0.5 In} 0.5 P.

  A portion including the lower spacer layer 104, the active layer 105, and the upper spacer layer 106 is also called a resonator structure, and is formed so that its optical thickness is λ (one wavelength). The active layer 105 is provided at the center of the resonator structure at a position corresponding to the antinode in the standing wave distribution of the electric field so as to obtain a high stimulated emission probability.

The upper semiconductor DBR 107 is stacked on the + Z side of the upper spacer layer 106. As shown in FIG. 2, the lower refractive index layer 107a made of p-Al _0.9 Ga _0.1 , p-Al _0. 23 pairs of high refractive index layers 107b made of ₃ Ga _0.7 As are alternately stacked. Between each refractive index layer, a composition gradient layer having a thickness of 20 nm is formed by gradually changing the composition from one composition to the other composition in order to reduce electric resistance. Each of the low refractive index layer 107a and the high refractive index layer 107b is formed so as to have an optical film thickness of λ / 4 including 1/2 of the film thickness of the adjacent composition gradient layer.

  One of the low refractive index layers in the upper semiconductor DBR 107 is provided with a current confinement layer 108 having a thickness of 30 nm formed of p-AlAs. The position where the current confinement layer 108 is provided is a position corresponding to the third node from the active layer 105 in the standing wave distribution of the electric field.

  The contact layer 109 is stacked on the + Z side of the upper semiconductor DBR 107 and is formed of p-GaAs.

  A buffer layer 102 to a contact layer 109 are formed on one surface of the GaAs substrate 101 by epitaxial growth, and then the active layer 105 is removed by etching to form a mesa 120. In the etching performed at this time, an ICP (Inductive Coupled Plasma) etching apparatus is used.

  After the mesa 120 is formed, oxidation with water vapor is performed to oxidize the current confinement layer 108 from the periphery of the mesa 120 to form a selective oxidation region 108a. As a result, in the current confinement layer 108, the unoxidized region becomes the current confinement region 108b, and a current flows through the current confinement region 108b.

  Next, an insulating film 111 is formed on the entire surface using SiN or the like, and after removing the insulating film 111 on the upper surface of the mesa 120, an anode electrode 113 is formed using Au / Ni or Au / Pt / Ti, and a GaAs substrate. A cathode electrode 114 is formed on the back surface of 101.

  Thereafter, the mounting surface of the surface emitting laser is exposed as a cleavage plane by cleaving into a bar shape. Further, an insulating film such as a silicon oxide film or a silicon nitride film is formed on this mounting surface by about 2 μm by vacuum deposition or sputtering. This insulating film is formed to maintain electrical insulation from the transmission line provided on the dielectric substrate when mounted on the dielectric substrate.

  Finally, the surface emitting laser bar is individualized by cleavage to complete a surface emitting laser chip that is a surface emitting laser element used in the present embodiment.

  Next, the connection between the anode electrode 113 and the transmission line in the surface emitting laser module according to the present embodiment will be described.

  The transmission line can send a high frequency signal from the signal source to the load side without loss by appropriately selecting its characteristic impedance. The characteristic impedance Z0 of the transmission line is expressed by the equation shown in Equation 2.

ここで、Ｌは単位長さあたりのインダクタンスであり、Ｃは単位長さあたりのキャパシタンスである。

Here, L is an inductance per unit length, and C is a capacitance per unit length.

  As a transmission line, one signal line of a dielectric substrate is a microstrip line in which a ground is disposed on the back surface, a signal line is disposed on one side of the dielectric substrate, and a ground is disposed on both sides of the signal line. There is a coplanar track. Some coplanar tracks also have a ground on the back.

  As can be seen from the equation (2), the characteristic impedance can be adjusted by a capacitance formed between the signal line and the ground. Specifically, the characteristic impedance is determined by adjusting the signal line width and the substrate thickness. Further, as the value of this characteristic impedance, generally 50Ω which is the same as the signal source impedance is selected.

(Surface emitting laser module)
Next, the surface emitting laser module in the present embodiment will be described. FIG. 3 shows a surface emitting laser chip 100a produced by cleaving. 3A is a front view of the surface emitting laser chip 100a, and FIG. 3B is a perspective view. The relative dielectric constant ε of the GaAs substrate 101 used in the present embodiment is 13. In this surface emitting laser chip, the signal electrode 130 is formed by the anode electrode 113 shown in FIG. 1, and the back surface ground electrode 140 is formed by the cathode electrode 114. A surface ground electrode 150 not shown in FIG. 1 is formed around the mesa 120 and the signal electrode 130. For example, the signal electrode 130 and the surface ground electrode 150 are formed by forming Au / Ni or Au / Pt / Ti or the like in a predetermined region on an insulating film 111 such as SiN formed on the entire surface of 0.3 μm. It is formed by.

  In the present embodiment, the thickness h1 of the GaAs substrate 101 is about 500 μm, and the signal electrode 130 gradually increases in width from w1 to w2 from the vicinity of the mesa 120 toward the periphery of the surface emitting laser chip. Is formed. The gap between the signal electrode 130 and the surface ground electrode 150 is formed so as to gradually widen from g1 to g2 from the vicinity of the mesa 120 toward the periphery of the surface emitting laser chip. In the present embodiment, since the characteristic impedance is about 50Ω, the width is 10 μm for w1 and 50 μm for w2, and the gap is formed so that g1 is 7 μm and g2 is 35 μm.

  FIG. 4 shows a surface emitting laser module according to the present embodiment. 4A is a front view, and FIG. 4B is a cross-sectional view taken along the alternate long and short dash line 4A-4B in FIG. 4A. The surface emitting laser module in the present embodiment is formed by bonding the surface emitting laser chip 100a shown in FIG. On the surface of the dielectric substrate 160, a signal coplanar line 171 and a ground coplanar line 172 are formed with a predetermined width and interval. In the dielectric substrate 160, the joining member such as solder wraps around the region connected to the signal electrode 130 and the surface ground electrode 150 on the surface of the surface emitting laser chip 100a and the region connected to the back surface ground electrode 140 on the back surface. In order to prevent, convex parts 161, 162 and 163 are provided. A signal coplanar line 171 is formed on the convex portion 161, and a ground coplanar line 172 is formed on the convex portions 162 and 163. The signal coplanar line 171 and the ground coplanar line 172 are made of, for example, Au / Ni or Au / Cu, and the surface thereof is joined with a solder or the like, for example, AuSn eutectic. Bonding layers 164 to 166 made of solder or the like are formed. The heights of the convex portions 161, 162, and 163 are about several tens of μm, and an insulating film 119 is formed on the surface of the surface emitting laser chip 100a in contact with the dielectric substrate 160.

  In the present embodiment, the signal coplanar line 171 and the ground coplanar line 172 on the dielectric substrate 160 are composed of the signal electrode 130, the front surface ground electrode 150, the rear surface ground electrode 140, and the bonding layers 164 to 164 of the surface emitting laser chip 100a. 166 is connected. That is, the signal electrode 130 in the surface emitting laser chip 100 a is connected to the signal coplanar line 171 in the bonding layer 164 provided on the convex portion 161. Further, in the surface emitting laser chip 100a, the front surface ground electrode 150 is in the bonding layer 165 provided on the convex portion 162, and the rear surface ground electrode 140 is in the bonding layer 166 provided on the convex portion 163. The coplanar line 172 is connected.

  Specifically, in the method of connecting the dielectric substrate 160 and the surface emitting laser chip 100a, first, the surface emitting laser chip 100a is placed on the bonding layers 164 to 166 of the convex portions 161 to 163 of the dielectric substrate 160. To do. Next, in a nitrogen atmosphere, a heat treatment is performed at 320 ° C. for several tens of seconds while applying a load of several tens to several hundreds of grams, whereby AuSn solder and the like are melted, and the signal electrode 130 on the surface emitting laser chip 100a side is formed. After wetting and spreading, it hardens by cooling and is connected by solder or the like.

  In the present embodiment, by directly connecting and bonding the dielectric substrate 160 and the surface emitting laser chip 100a with a bonding member such as solder, it is possible to obtain a surface emitting laser module excellent in high speed and high frequency characteristics at low cost. it can.

[Second Embodiment]
Next, a second embodiment will be described. This embodiment has a structure in which a surface emitting laser chip 200a in which surface emitting lasers similar to those of the first embodiment are arranged one-dimensionally is bonded to a dielectric substrate 260.

  As shown in FIGS. 5 and 6, a plurality of surface emitting lasers are arranged one-dimensionally on the surface emitting laser chip 200a, and a signal electrode 130 is provided in each surface emitting laser. 6A shows a state before the surface emitting laser chip 200a and the dielectric substrate 260 are joined, and FIG. 6B shows a state where the surface emitting laser chip 200a and the dielectric substrate 260 are joined. Indicates the state that has been performed. In FIG. 6B, details of the joining region are omitted for convenience. In the surface emitting laser chip 200a, the surface ground electrode 250 similar to the surface ground electrode 150 in the first embodiment is provided on the surface where the signal electrode 130 is provided, and the back surface ground electrode is provided on the back surface. A back surface ground electrode 240 similar to 140 is provided. The dielectric substrate 260 is provided with a plurality of bonding layers 164 to 166 corresponding to the signal electrode 130, the front surface ground electrode 250, and the rear surface ground electrode 240, and the corresponding coplanar lines and signals corresponding to the bonding layers 164 to 166 are provided. Connected to the ground coplanar track.

  The contents other than the above are the same as in the first embodiment.

[Third Embodiment]
Next, a surface emitting laser module according to the third embodiment will be described. As shown in FIG. 7, the surface emitting laser module according to the present embodiment is obtained by cleaving the surface emitting laser similar to the surface emitting laser according to the first embodiment. It is the thing of the structure joined to. The relative dielectric constant ε of the GaAs substrate 101 used in the surface emitting laser chip 300a is 13. In the surface emitting laser chip 300a, the signal electrode 330 is formed by the anode electrode 113 shown in FIG. 1, and the back surface ground electrode 340 is formed by the cathode electrode 114. For example, the signal electrode 330 is formed by forming Au / Ni or Au / Pt / Ti or the like in a predetermined region on an insulating film 111 such as SiN formed on the entire surface of 0.3 μm. Yes.

  In the present embodiment, the thickness h2 of the GaAs substrate 101 is about 450 μm, and the signal electrode 330 is formed to have a substantially constant width w3 from the vicinity of the mesa 120 to the periphery of the surface emitting laser chip. Has been. In this embodiment, in order to set the characteristic impedance to 50Ω, the width is formed such that w3 is 327 μm. In order to reduce the reflection component, the end of the microstrip line of the signal electrode 330 is formed in a tapered shape.

  A signal transmission line 371 and a ground transmission line (not shown) are formed on the surface of the dielectric substrate 360 with a predetermined width and interval. In the dielectric substrate 360, a convex portion is provided in a region connected to the signal electrode 330 on the surface of the surface emitting laser chip 300a and a region connected to the back surface ground electrode 340 on the back surface in order to prevent a joining member from wrapping around by solder or the like. 361 and the like are provided. A signal transmission line 371 is formed on the convex part 361, and a ground transmission line is formed on the convex part (not shown). The transmission line for signal 371 and the transmission line for ground are made of, for example, Au / Ni or Au / Cu, and the surface thereof is further joined with solder or the like, for example, AuSn eutectic solder. A bonding layer 364 or the like is formed. In addition, the height of the convex part 361 etc. is formed about several tens of micrometers.

  In the present embodiment, the signal transmission line 371 and the ground transmission line in the dielectric substrate 360 are connected to the signal electrode 330 and the back ground electrode 340 of the surface emitting laser chip 300a by the bonding layer 364 and the like. That is, the signal electrode 330 in the surface emitting laser chip 300 a is connected to the signal transmission line 371 in the bonding layer 364 provided on the convex portion 361. Further, the back surface ground electrode 340 in the surface emitting laser chip 300a is connected to a ground transmission line in a bonding layer provided on a convex portion (not shown).

  Specifically, in the method of connecting the dielectric substrate 360 and the surface emitting laser chip 300a, first, the surface emitting laser chip 300a is mounted on the bonding layer 364 such as the convex portion 361 of the dielectric substrate 360. . Next, heat treatment is performed at 320 ° C. for several tens of seconds while applying a load of several tens to several hundreds of grams in a nitrogen atmosphere, whereby AuSn solder and the like are melted, and the signal electrodes 330 and the like on the surface emitting laser chip 300a side are melted. After wetting and spreading, it hardens by cooling and is connected by solder or the like.

  In the present embodiment, by directly connecting and bonding the dielectric substrate 360 and the surface emitting laser chip 300a with a bonding member such as solder, it is possible to obtain a surface emitting laser module excellent in high speed and high frequency characteristics at low cost. it can.

  The contents other than the above are the same as in the first embodiment.

[Fourth Embodiment]
Next, a fourth embodiment will be described. This embodiment has a structure in which a surface emitting laser chip 400a in which surface emitting lasers similar to those of the third embodiment are arranged one-dimensionally is bonded to a dielectric substrate 460.

  As shown in FIG. 8, the surface emitting laser chip 400a has a plurality of surface emitting lasers arranged one-dimensionally, and a signal electrode 330 is provided for each surface emitting laser. 8A shows a state before the surface emitting laser chip 400a and the dielectric substrate 460 are joined, and FIG. 8B shows a state where the surface emitting laser chip 400a and the dielectric substrate 460 are joined. Indicates the state that has been performed. In FIG. 8B, details of the joining region are omitted for convenience. A back surface ground electrode 440 similar to the back surface ground electrode 340 in the third embodiment is provided on the back surface of the surface emitting laser chip 400a. The dielectric substrate 460 is provided with a bonding layer 464 for connection to the signal transmission line 471 corresponding to the signal electrode 330, and is connected to the corresponding signal transmission line 471 by the bonding layer 464. The A ground portion 461 is provided on the back surface of the dielectric substrate 460, and the back surface ground electrode 440 is formed on the back surface of the dielectric substrate 460 by a through electrode 481 exposed on the surface of the dielectric substrate 460 formed in the via. The ground portion 461 is connected.

  The contents other than those described above are the same as in the third embodiment.

[Fifth Embodiment]
Next, a fifth embodiment will be described. The present embodiment is a laser printer 1000 which is an image forming apparatus using the surface emitting laser module in the first to fourth embodiments.

  Based on FIG. 9, the laser printer 1000 in this Embodiment is demonstrated. The laser printer 1000 according to this embodiment includes an optical scanning device 1010, a photosensitive drum 1030, a charging charger 1031, a developing roller 1032, a transfer charger 1033, a charge eliminating unit 1034, a cleaning unit 1035, a toner cartridge 1036, a paper feeding roller 1037, a feeding roller. A paper tray 1038, a registration roller pair 1039, a fixing roller 1041, a paper discharge roller 1042, a paper discharge tray 1043, a communication control device 1050, and a printer control device 1060 that comprehensively controls each of the above parts are provided. These are housed in predetermined positions in the printer housing 1044.

  The communication control device 1050 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  The photosensitive drum 1030 is a cylindrical member, and a photosensitive layer is formed on the surface thereof. That is, the surface of the photoconductor drum 1030 is a scanned surface. The photosensitive drum 1030 rotates in the direction indicated by the arrow X.

  The charging charger 1031, the developing roller 1032, the transfer charger 1033, the charge removal unit 1034, and the cleaning unit 1035 are each disposed in the vicinity of the surface of the photosensitive drum 1030. Then, along the rotation direction of the photosensitive drum 1030, the charging charger 1031 → the developing roller 1032 → the transfer charger 1033 → the discharging unit 1034 → the cleaning unit 1035 are arranged in this order.

  The charging charger 1031 uniformly charges the surface of the photosensitive drum 1030.

  The optical scanning device 1010 scans the surface of the photosensitive drum 1030 charged by the charging charger 1031 with a light beam modulated based on image information from the host device, and corresponds to the image information on the surface of the photosensitive drum 1030. A latent image is formed. The latent image formed here moves in the direction of the developing roller 1032 as the photosensitive drum 1030 rotates. The configuration of the optical scanning device 1010 will be described later.

  Toner cartridge 1036 stores toner, and this toner is supplied to developing roller 1032.

  The developing roller 1032 causes the toner supplied from the toner cartridge 1036 to adhere to the latent image formed on the surface of the photosensitive drum 1030 to visualize the image information. Here, the latent image to which the toner is attached (hereinafter also referred to as “toner image” for the sake of convenience) moves in the direction of the transfer charger 1033 as the photosensitive drum 1030 rotates.

  Recording paper 1040 is stored in the paper feed tray 1038. A paper feed roller 1037 is disposed in the vicinity of the paper feed tray 1038. The paper feed roller 1037 takes out the recording paper 1040 one by one from the paper feed tray 1038 and conveys it to the registration roller pair 1039. The registration roller pair 1039 temporarily holds the recording paper 1040 taken out by the paper supply roller 1037, and in the gap between the photosensitive drum 1030 and the transfer charger 1033 according to the rotation of the photosensitive drum 1030. Send it out.

  A voltage having a polarity opposite to that of the toner is applied to the transfer charger 1033 in order to electrically attract the toner on the surface of the photosensitive drum 1030 to the recording paper 1040. With this voltage, the toner image on the surface of the photosensitive drum 1030 is transferred to the recording paper 1040. The recording sheet 1040 transferred here is sent to the fixing roller 1041.

  In the fixing roller 1041, heat and pressure are applied to the recording paper 1040, whereby the toner is fixed on the recording paper 1040. The recording paper 1040 fixed here is sent to the paper discharge tray 1043 via the paper discharge roller 1042 and is sequentially stacked on the paper discharge tray 1043.

  The neutralization unit 1034 neutralizes the surface of the photosensitive drum 1030.

  The cleaning unit 1035 removes the toner remaining on the surface of the photosensitive drum 1030 (residual toner). The surface of the photosensitive drum 1030 from which the residual toner has been removed returns to the position facing the charging charger 1031 again.

  Next, the optical scanning device 1010 will be described with reference to FIG. The optical scanning device 1010 collectively includes a light source unit 1100, a coupling lens 1111, an aperture 1112, a cylindrical lens 1113, a polygon mirror 1114, an fθ lens 1115, a toroidal lens 1116, two mirrors (1117, 1118), and the above parts. A control device (not shown) for controlling is provided. The light source unit 1100 includes any one of the surface emitting laser modules in the first to fourth embodiments.

  The coupling 1111 shapes the laser light emitted from the surface emitting laser in the light source unit 1100 into substantially parallel light.

  The aperture 1112 defines the laser light from the coupling lens 1111 so as to have a predetermined beam shape.

  The cylindrical lens 1113 condenses the light output from the light source unit 1100 in the vicinity of the deflection reflection surface of the polygon mirror 1114 via the mirror 1117.

  The polygon mirror 1114 is made of a regular hexagonal columnar member having a low height, and six deflection reflection surfaces are formed on the side surface. Then, it is rotated at a constant angular velocity in the direction indicated by the arrow Y by a rotation mechanism (not shown).

  Accordingly, the light emitted from the light source unit 1100 and condensed near the deflection reflection surface of the polygon mirror 1114 by the cylindrical lens 1113 is deflected at a constant angular velocity by the rotation of the polygon mirror 1114.

  The fθ lens 1115 has an image height proportional to the incident angle of light from the polygon mirror 1114, and moves the image surface of light deflected by the polygon mirror 1114 at a constant angular velocity with constant speed in the main scanning direction. The toroidal lens 1116 forms an image of the light from the fθ lens 1115 on the surface of the photosensitive drum 1030 via the mirror 1118.

  The toroidal lens 1116 is disposed on the optical path of the light beam through the fθ lens 1115. Then, the light beam that has passed through the toroidal lens 1116 is irradiated onto the surface of the photosensitive drum 1030 to form a light spot. This light spot moves in the longitudinal direction of the photosensitive drum 1030 as the polygon mirror 1114 rotates. That is, the photoconductor drum 1030 is scanned. The moving direction of the light spot at this time is the “main scanning direction”. The rotation direction of the photosensitive drum 1030 is the “sub-scanning direction”.

  The optical system arranged on the optical path between the polygon mirror 1114 and the photosensitive drum 1030 is also called a scanning optical system. In the present embodiment, the scanning optical system includes an fθ lens 1115 and a toroidal lens 1116. Note that at least one folding mirror may be disposed on at least one of the optical path between the fθ lens 1115 and the toroidal lens 1116 and on the optical path between the toroidal lens 1116 and the photosensitive drum 1030.

  Since the laser printer 1000 according to the present embodiment uses any of the surface emitting laser modules according to the first to fourth embodiments, the laser printer 1000 is excellent in high-speed operation and high-frequency characteristics, and therefore prints at a high printing speed. be able to.

  In the description of the present embodiment, the case of the laser printer 1000 as the image forming apparatus has been described. However, the present invention is not limited to this.

  For example, an image forming apparatus that directly irradiates laser light onto a medium (for example, paper) that develops color with laser light may be used.

  Further, an image forming apparatus using a silver salt film as the image carrier may be used. In this case, a latent image is formed on the silver salt film by optical scanning, and this latent image can be visualized by a process equivalent to a developing process in a normal silver salt photographic process. Then, it can be transferred to photographic paper by a process equivalent to a printing process in a normal silver salt photographic process. Such an image forming apparatus can be implemented as an optical plate making apparatus or an optical drawing apparatus that draws a CT scan image or the like.

[Sixth Embodiment]
Next, a sixth embodiment will be described. The sixth embodiment is a color printer 2000 including a plurality of photosensitive drums.

  A color printer 2000 according to the present embodiment will be described with reference to FIG. The color printer 2000 in the present embodiment is a tandem multicolor printer that forms a full-color image by superimposing four colors (black, cyan, magenta, and yellow). “Charging device K2, developing device K4, cleaning unit K5, and transfer device K6”, “photosensitive drum C1, charging device C2, developing device C4, cleaning unit C5, and transfer device C6” for cyan, and magenta “Photosensitive drum M1, charging device M2, developing device M4, cleaning unit M5, and transfer device M6” and yellow “photosensitive drum Y1, charging device Y2, developing device Y4, cleaning unit Y5, and transfer device Y6” ”, Optical scanning device 2010, transfer belt 2080, fixing unit 2030, and the like. It is equipped with a.

  Each photoconductor drum rotates in the direction of the arrow shown in FIG. 11, and a charging device, a developing device, a transfer device, and a cleaning unit are arranged around each photoconductor drum in the order of rotation. Each charging device uniformly charges the surface of the corresponding photosensitive drum. The surface of each photoconductive drum charged by the charging device is irradiated with light by the optical scanning device 2010, and a latent image is formed on each photoconductive drum. Then, a toner image is formed on the surface of each photosensitive drum by a corresponding developing device. Further, the toner image of each color is transferred onto the recording paper on the transfer belt 2080 by the corresponding transfer device, and finally the image is fixed on the recording paper by the fixing unit 2030.

  The optical scanning device 2010 has any one of the surface emitting laser modules in the first to fourth embodiments for each color, and is similar to the optical scanning device 1010 described in the fifth embodiment. The effect can be obtained, and furthermore, the color printer 2000 can obtain the same effect as the laser printer 1000 in the fifth embodiment.

  Therefore, since the color printer 2000 according to the present embodiment uses the surface emitting laser module according to any one of the first to fourth embodiments, a high-quality image can be formed at high speed. it can.

  As mentioned above, although the form which concerns on implementation of this invention was demonstrated, the said content does not limit the content of invention.

100 surface emitting laser element 100a surface emitting laser chip 101 GaAs substrate 102 buffer layer 103 lower semiconductor DBR
104 Lower spacer layer 105 Active layer 106 Upper spacer layer 107 Upper semiconductor DBR
108 Current confinement layer 108a Selective oxidation region 108b Current confinement region 109 Contact layer 111 Insulating film 113 Anode electrode 114 Cathode electrode 119 Insulating film 120 Mesa 130 Signal electrode 140 Back surface ground electrode 150 Front surface ground electrode 160 Dielectric substrate 161 Convex portion 162 Convex portion 163 Projection 164 Bonding layer 165 Bonding layer 166 Bonding layer 171 Coplanar line 172 for signal Coplanar line 1000 for ground Laser printer (image forming apparatus)
1010 Optical scanning device 2000 Color printer (image forming apparatus)

JP 2008-47717 A

Claims (10)

A surface emitting laser chip having a surface emitting laser that emits light in a direction perpendicular to the semiconductor substrate surface;
A dielectric substrate connected to a side surface of the surface emitting laser chip;
Have
In the surface emitting laser chip, a signal electrode is formed on one surface that emits the light, and a back surface ground electrode is formed on the other surface opposite to the surface on which the signal electrode is formed. And
A signal transmission line connected to the signal electrode is formed on one surface of the dielectric substrate,
The surface emitting laser module, wherein the signal electrode and the signal transmission line are connected.   2. The surface emitting laser module according to claim 1, wherein the signal transmission line is formed on a convex portion formed on a surface of the dielectric substrate.   3. The surface emitting laser module according to claim 1, wherein the signal electrode and the signal transmission line are connected by solder.   A ground portion is formed on the other surface of the dielectric substrate, and the back surface ground electrode and the ground portion of the surface emitting laser chip are connected via a through electrode provided on the dielectric substrate. The surface emitting laser module according to claim 1, wherein the surface emitting laser module is a module.   5. The surface emitting laser module according to claim 1, wherein the signal transmission line is a microstrip line. A surface ground electrode is formed around the signal electrode on the one surface,
On one surface of the dielectric substrate, a ground transmission line connected to the back surface ground electrode and the surface ground electrode is formed,
The surface emitting laser module according to any one of claims 1 to 3, wherein a back surface ground electrode and a surface ground electrode are connected to the ground transmission line.   The surface emitting laser module according to claim 6, wherein the ground transmission line is formed on a convex portion formed on a surface of the dielectric substrate. The back surface ground electrode and the front surface ground electrode and the transmission line for the ground,
The surface emitting laser module according to claim 6, wherein the surface emitting laser module is connected by solder.   9. The surface emitting laser module according to claim 6, wherein the signal transmission line and the ground transmission line are coplanar lines.   10. The surface emitting laser module according to claim 1, wherein an insulating film is formed on a surface bonded to the dielectric substrate in the surface emitting laser chip. 11.

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