semiconductor optical devices

Abstract

To make it possible to easily manufacture a semiconductor optical device such as an EA-DFB laser.SOLUTION: A semiconductor optical device includes an optical waveguide structure having an active layer 104 formed on a substrate 101 as a core. The optical waveguide structure includes a laser area 131 composed of a distributed feedback laser and an area 132 composed of a field-absorption modulator arranged contiguously to the laser area 131. The active layer 104 on the modulation area 132 is composed of a plurality of well structures 104a periodically separated in a waveguide direction. With such a configuration, an absorption edge wavelength of the active layer 104 of the modulation area 132 is made shorter than an absorption edge wavelength of the active layer 104 of the laser area 131.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a semiconductor optical device used in an optical transmitter or the like. [Background technology]

[0002] The spread of the Internet and mobile networks has led to an explosive increase in network traffic. The increase in data traffic is now required for all types of communication, from long-distance optical fiber communications to short-distance interconnections, and the demand for larger capacity and faster data communications is unrelenting.

[0003] Against this background, with the recent increase in data communication volume, attention has been focused on modulated light sources with high baud rates exceeding 50 GBaud. 50 GBaud-class optical transceivers, such as 100GBASE-DR and 400GBASE-DR4, have already been standardized as Internet standards, and further developments in modulated light sources with even higher baud rates are expected in the future.

[0004] From the viewpoint of power consumption, semiconductor optical devices such as directly modulated lasers, which modulate the laser drive current, are promising as high-speed modulated light sources. The modulation bandwidth of directly modulated lasers has long been limited by the relaxation oscillation frequency, but in recent years, new effects have been proposed to extend the modulation bandwidth, such as optical-optical resonance, and a modulated laser with a 3 dB bandwidth of nearly 100 GHz has been reported at the experimental level (Non-Patent Document 1).

[0005] On the other hand, one semiconductor optical device that has been commercialized as a modulated light source suitable for simple and high-speed modulation is the EA-DFB laser, which integrates an electroabsorption (EA) modulator and a distributed feedback (DFB) laser. Figure 7 shows the structure of a conventional, general EA-DFB laser.

[0006] This laser comprises a laser region 331 and a modulation region 332 on a substrate 301 made of n-type InP. The laser region 331 comprises a quantum well active layer 302 for the laser made of InGaAsP, and oscillates at a single wavelength due to a diffraction grating 303 formed in the resonator. The modulation region 332 comprises an active layer 304 for the modulator made of InGaAsP. The absorption edge wavelength of the quantum well active layer 302 is set to be longer than the absorption edge wavelength of the active layer 304.

[0007] The quantum well active layer 302 and the active layer 304 are sandwiched between a lower optical confinement layer 305 and an upper optical confinement layer 306, forming a separate confined heterostructure (SCH) structure. The diffraction grating 303 is composed of a periodic uneven pattern formed on the upper surface of the upper optical confinement layer 306. A semiconductor layer 307 made of p-type InP is formed on the upper optical confinement layer 306, and p-electrodes 308 and 309 are formed in the laser region 331 and the modulation region 332, respectively. An n-electrode 310 is formed on the back surface of the substrate 301.

[0008] A forward bias is applied to the laser region 331 to perform laser oscillation by current injection, and a reverse bias is applied to the modulation region 332 to perform intensity modulation by the quantum confined Stark effect (QCSE) due to the quantum well. High-speed modulation operations exceeding 40 Gbit / s have been reported using this EA-DFB laser (Non-Patent Document 2), and it has been applied to commercial optical transmitters including 10 Gbit / s. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] S. Yamaoka et al., "Directly modulated membrane lasers with 108 GHz bandwidth on a high-thermal-conductivity silicon carbide substrate", Nature Photonics, vol. 15, pp. 28-35, 2021. [Non-patent document 2] W. Kobayashi et al., "Design and Fabrication of 10- / 40-Gb / s, Uncooled Electroabsorption Modulator Integrated DFB Laser With Butt-Joint Structure", Journal of Lightwave Technology, vol. 28, no. 1, pp. 164-171, 2010. Summary of the Invention [Problem to be solved by the invention]

[0010] As mentioned above, conventional EA-DFB lasers have different absorption edge wavelengths for the active layer in the modulation region and the active layer in the laser region. This requires the formation of different active layers for the modulation region and the laser region. Such a configuration requires crystal growth techniques, such as multiple butt-joint growth of the active layer or bandgap control by selective growth in each active layer. Thus, conventional semiconductor optical devices such as EA-DFB lasers have been difficult to manufacture.

[0011] The present invention has been made to solve the above problems, and has as its object to make it possible to easily manufacture semiconductor optical devices such as EA-DFB lasers. [Means for solving the problem]

[0012] A semiconductor optical device according to the present invention comprises an optical waveguide structure having an active layer formed on a substrate as a core, the optical waveguide structure comprising a laser region made of a distributed feedback laser and a modulation region made of an electro-absorption modulator disposed contiguous with the laser region, and the active layer in the modulation region is composed of a plurality of well structures periodically separated in the waveguiding direction so that the absorption edge wavelength of the active layer in the modulation region is shorter than the absorption edge wavelength of the active layer in the laser region. [Effects of the Invention]

[0013] As described above, according to the present invention, the active layer of the modulation region is constructed from a plurality of well structures periodically separated in the waveguiding direction, so that semiconductor optical devices such as EA-DFB lasers can be easily manufactured. [Brief explanation of the drawings]

[0014] [Figure 1A] FIG. 1A is a cross-sectional view showing a partial configuration of a semiconductor optical device according to a first embodiment of the present invention. [Figure 1B] FIG. 1B is a perspective view showing the configuration of the semiconductor optical device according to the first embodiment of the present invention. [Figure 2A] FIG. 2A is a cross-sectional view showing a partial configuration of a semiconductor optical device according to the first embodiment of the present invention. [Figure 2B] FIG. 2B is a cross-sectional view showing a partial configuration of the semiconductor optical device according to the first embodiment of the present invention. [Figure 2C] FIG. 2C is a cross-sectional view showing a partial configuration of the semiconductor optical device according to the first embodiment of the present invention. [Figure 3A] FIG. 3A is a characteristic diagram showing the dependence of the operating wavelength (ground level transition wavelength) of the active layer 104, which is a multiple quantum well layer with well layer thicknesses of 4 nm, 6 nm, and 8 nm, on the active layer width DMOD and DLD. [Figure 3B] FIG. 3B is a characteristic diagram showing the dependence of the transition wavelength interval between the ground level and the excited level on the active layer width DMOD and DLD in the active layer 104 formed as a multiple quantum well layer with well layer thicknesses of 4 nm, 6 nm, and 8 nm. [Figure 4]FIG. 4 is a characteristic diagram showing the absorption spectrum of the optical modulator configured in the modulation region 132 and the gain spectrum of the laser configured in the laser region 131. [Figure 5A] FIG. 5A is an explanatory diagram for explaining a state in which the Bragg wavelength λbMOD of the modulation region 132 is arranged on the shorter wavelength side with respect to the Bragg wavelength λbLD of the laser region 131. In FIG. [Figure 5B] FIG. 5B is an explanatory diagram for explaining a state in which the Bragg wavelength λbMOD of the modulation region 132 is arranged on the longer wavelength side with respect to the Bragg wavelength λbLD of the laser region 131. [Figure 5C] FIG. 5C is an explanatory diagram for explaining a state in which the stop band of the modulation region 132 is placed within the stop band of the diffraction grating of the laser region 131. [Figure 6A] FIG. 6A is a cross-sectional view showing the configuration of a semiconductor optical device according to a second embodiment of the present invention. [Figure 6B] FIG. 6B is a perspective view showing the configuration of the semiconductor optical device according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view showing the structure of a conventional general EA-DFB laser. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, a semiconductor optical device according to an embodiment of the present invention will be described.

[0016] [Embodiment 1] First, a semiconductor optical device according to a first embodiment of the present invention will be described with reference to FIGS. 1A, 1B, 2A, and 2B.

[0017] This semiconductor optical device has an optical waveguide structure with an active layer 104 formed on a substrate 101 as a core, and the optical waveguide structure includes a laser region 131 made of a distributed feedback laser and a modulation region 132 made of an electroabsorption modulator arranged contiguous with the laser region 131. This semiconductor optical device is a well-known EA-DFB laser. Note that FIG. 1A shows a cross section of a plane perpendicular to the surface of the substrate 101 and parallel to the waveguide direction. Also, FIGS. 2A and 2B show cross sections of a plane perpendicular to the waveguide direction.

[0018] In this semiconductor optical device, the active layer 104 in the modulation region 132 is composed of a plurality of well structures 104a that are periodically separated in the waveguiding direction. With this configuration, the absorption edge wavelength of the active layer 104 in the modulation region 132 is set to be shorter than the absorption edge wavelength of the active layer 104 in the laser region 131. The active layer 104 in the modulation region 132 has a multiple quantum well structure composed of the well structures 104a in the waveguiding direction.

[0019] Note that a cladding layer 102 is formed on the substrate 101, and a semiconductor layer 103 is formed on the cladding layer 102. The active layer 104 is buried in the semiconductor layer 103. Therefore, in the cross section of the modulation region 132 perpendicular to the waveguide direction, there are areas where the well structure 104a appears sandwiched between the semiconductor layers 103 on the top and bottom, as shown in Fig. 2A, and areas where only the semiconductor layer 103 appears, as shown in Fig. 2B.

[0020] In the first embodiment, the active layer 104 of the laser region 131 is also composed of a plurality of well structures 104b periodically separated in the waveguide direction. The laser region 131 thus configured functions as a resonator by forming a diffraction grating with the active layer 104 composed of a plurality of well structures 104b periodically separated in the waveguide direction.

[0021] In the first embodiment, the active layer 104 is of a lateral current injection type and a lateral voltage application type sandwiched between a p-type semiconductor layer 106 and an n-type semiconductor layer 107 in the planar direction of the substrate 101. The laser region 131 is of a lateral current injection type in which a current is injected in the planar direction of the substrate 101. The modulation region 132 is of a lateral voltage application type in which a voltage is applied in the planar direction of the substrate 101. In the modulation region 132, a first p-electrode 110 is formed on the p-type semiconductor layer 106 with a first p-type contact layer 108 interposed therebetween. In the modulation region 132, a first n-electrode 111 is formed on the n-type semiconductor layer 107 with a first n-type contact layer 109 interposed therebetween.

[0022] In the laser region 131, a second p-electrode 114 is formed on the p-type semiconductor layer 106 with a second p-type contact layer 112 interposed therebetween. In the laser region 131, a second n-electrode 115 is formed on the n-type semiconductor layer 107 with a second n-type contact layer 113 interposed therebetween. The active layer 104 may have a multiple quantum well structure in the thickness direction, or may have a so-called bulk structure.

[0023] For example, the substrate 101 may be a silicon substrate. The cladding layer 102 may be made of, for example, silicon oxide (SiO2) and have a thickness of about 2 μm. The semiconductor layer 103 may be made of, for example, a compound semiconductor such as undoped InP. The semiconductor layer 103 may have a thickness of 350 nm.

[0024] The active layer 104 may have a multiple quantum well structure using quantum well layers made of InGaAsP. For example, the active layer 104 may be a multiple quantum well layer using six well layers, each having a width of 700 nm and a thickness of 6 nm. As shown in FIG. 2C, the active layer 104 may be a multiple quantum well layer having well layers 141 made of InGaAsP with a small band gap and barrier layers 142 made of InGaAsP with a large band gap. The active layer 104 may have a total thickness of, for example, 100 nm. In this case, the thickness of the semiconductor layer 103 in the lower part of the active layer 104 may be 150 nm, and the thickness of the semiconductor layer 103 in the upper part may be 100 nm.

[0025] The p-type semiconductor layer 106 is made of, for example, InP and has a thickness of about 300 nm. The p-type semiconductor layer 106 contains Zn as a p-type dopant at a concentration of 1×10 18 cm -3 The n-type semiconductor layer 107 is made of InP and has a thickness of about 300 nm. The n-type semiconductor layer 107 contains Si as an n-type dopant at a concentration of about 1×10 18 cm -3 The semiconductor layer 103 is doped at a concentration of about 100 nm. In this example, the thickness (ridge height) of the portions of the semiconductor layer 103 that protrude from the upper surfaces of the p-type semiconductor layer 106 and the n-type semiconductor layer 107 is 50 nm. The thicknesses of the p-type semiconductor layer 106 and the n-type semiconductor layer 107 can also be 250 nm. In this case, the thickness (ridge height) of the portions of the semiconductor layer 103 that protrude from the upper surfaces of the p-type semiconductor layer 106 and the n-type semiconductor layer 107 is 100 nm.

[0026] The first p-type contact layer 108 and the second p-type contact layer 112 are made of, for example, InGaAs and have a concentration of 1×10 19 cm -3 The first n-type contact layer 109 and the second n-type contact layer 113 are doped with a p-type dopant to a concentration of about 1×10 19 cm -3The active layer 104 is not present between the laser region 131 and the modulation region 132, and an optical waveguide having the semiconductor layer 103 as its core is formed.

[0027] In this configuration, the height (thickness) of the semiconductor layer 103, which forms the core region, from the upper surface of the cladding layer 102 is 350 nm, and the thicknesses of the p-type semiconductor layer 106 and the n-type semiconductor layer 107 are 300 nm, so that it functions as a rib-type waveguide, and lateral light confinement to the core region by the semiconductor layer 103 is ensured.

[0028] In the first embodiment, the width D of the well structure 104a in the modulation region 132 in the waveguiding direction (light propagation direction) MOD and the interval Λ MOD and the width D in the waveguide direction of the well structure 104b in the laser region 131. LD and the interval Λ LD For example, D MOD is 30 nm, Λ MOD is set to 100 nm, and D LD is 200 nm, Λ LD can be 276 nm.

[0029] In each of the above dimensions, the Bragg wavelength λ of the laser formed by the laser region 131 bLD The length of the modulation region 132 in the waveguide direction can be set to 300 μm, and the length of the laser region 131 in the waveguide direction can be set to 100 μm.

[0030] 1B, no contact layer or electrode is formed in the connection region between the modulation region 132 and the laser region 131, so that they are electrically isolated. A voltage is applied in the reverse bias direction between the first p electrode 110 and the first n electrode 111 of the modulation region 132, and a voltage is applied in the forward bias direction between the second p electrode 114 and the second n electrode 115 of the laser region 131.

[0031] Next, the operation and effects of the semiconductor optical device according to the embodiment, which is an EA-DFB laser, will be described.

[0032] In the semiconductor device according to the first embodiment, the well structures 104a in the modulation region 132 and the well structures 104b in the laser region 131 are set to different widths and are periodically arranged. MOD The width D of the well structure 104b in the laser region 131 LD The active layer 104 of the modulation region 132, which is made up of a plurality of well structures 104a, is made thinner than the transition wavelength or absorption edge wavelength λ MOD is the transition wavelength or absorption edge wavelength λ of the active layer 104 that is continuous in the waveguiding direction. well The wavelength becomes shorter than that.

[0033] 3A and 3B show the active layer width D of the active layer 104, which is a multiple quantum well layer with well layer thicknesses of 4 nm, 6 nm, and 8 nm, at the operating wavelength. MOD and D LD 3A shows the transition wavelength between ground levels, and FIG. 3B shows the transition wavelength interval between the ground level and the excited level. As the active layer width becomes narrower, the transition wavelength becomes shorter due to the appearance of two-dimensional quantum effects, and the transition wavelength interval also becomes wider. As an example, the well width is set to 6 nm, and D MOD is 30nm, D LD is 200 nm, the transition wavelength of the modulation region 132 is 1.5 μm and the transition wavelength of the laser region 131 is 1.55 μm, and the absorption edge of the modulation region 132 is detuned 50 nm to the shorter wavelength side with respect to the laser region 131. In addition, the wavelength interval between the ground level and the excited level is 80 nm in the modulation region 132 and 1.5 nm in the laser region 131, and a strong quantum effect appears in the modulation region 132.

[0034] The absorption spectrum of the optical modulator configured in the modulation region 132 thus configured and the gain spectrum of the laser configured in the laser region 131 are shown in FIG. MOD In this configuration, the wavelength of the laser becomes shorter, and a steep absorption spectrum appears due to the quantum effect. LD λ MODBy making the wavelength longer than the absorption edge wavelength, it is possible to suppress the propagation loss when no voltage is applied to the modulation region 132. When a reverse bias voltage is applied to the modulation region 132, the absorption edge shifts to the longer wavelength side due to the one-dimensional Franz-Keldysh effect, increasing the absorption loss in the operating wavelength region of the laser configured in the laser region 131, thereby achieving intensity modulation.

[0035] In this intensity modulation, electron-hole pairs generated by light absorption are swept without barriers in the thickness direction and horizontal direction in the quantum well structure constituting the thickness direction of active layer 104 and the quantum well structure in the waveguide direction formed by multiple well structures 104a, thereby realizing high-speed modulation operation. Furthermore, since semiconductor layer 103 has a relatively thin structure with a thickness of 350 nm, the parasitic capacitance of the element per unit length is low, which is effective in terms of high-speed operation in terms of the CR time constant.

[0036] The laser region 131 has a plurality of well structures 104b that constitute the active layer 104, arranged periodically, and functions as a composite Bragg diffraction grating with refractive index coupling and gain coupling. By adopting this structure, stable single-mode operation of the long wavelength stop band of the diffraction grating can be achieved even when a uniform diffraction grating structure is used without providing a phase shift or the like (reference). In this example, the Bragg wavelength of the laser region 131 is 1.55 μm. The coupling coefficient of the active layer 104 is 1000 cm -1 This allows realization of a high coupling coefficient that allows the formation of a small laser resonator.

[0037] Furthermore, the gain coupling effect of the multiple well structures 104b is effective in improving the resistance to reflection. Note that, since a periodic active layer structure is formed in the modulation region 132 using the multiple well structures 104a, a Bragg diffraction grating is also formed in the modulation region 132. In this configuration, as shown in Figures 5A and 5B, the Bragg wavelength λ bMOD The Bragg wavelength λ of the laser region 131 bLDBy arranging the modulation region 132 on the shorter or longer wavelength side of the laser region, it is possible to suppress the influence of reflection from the modulation region 132 on the laser oscillation light. In this example, the Bragg wavelength of the modulation region 132 is 560 nm, and the reflection spectrum of the modulation region 132 is arranged on the significantly shorter wavelength side than the transmission spectrum of the laser region.

[0038] 5C, when the stop band of the modulation region 132 is set to be located within the stop band of the diffraction grating of the laser region 131, spontaneous emission of the laser is suppressed, which is effective in suppressing the influence of reflection from the modulation region 132. According to the semiconductor optical device of the first embodiment described above, an integrated modulation light source that uses a single active layer 104 and is applicable to high-speed modulation of the 50 Gbaud class can be realized.

[0039] The semiconductor optical device according to the embodiment can be fabricated by an existing device fabrication method. For example, SiO2 is formed on a silicon substrate, and a compound semiconductor layer formed by epitaxial growth on an InP substrate is bonded using a bonding technique such as oxygen plasma assisted bonding. On this compound semiconductor layer, the active layer 104 is grown or buried by metal organic chemical vapor deposition, thereby forming the semiconductor layer 103.

[0040] The shape of the semiconductor layer 103 and the well structures 104a and 104b in the active layer 104 can be formed by known processes such as photolithography, electron beam lithography, and wet and dry etching. The p-type semiconductor layer 106 and the n-type semiconductor layer 107 may be formed by InP regrowth, or by forming undoped InP and a contact InGaAs layer and then introducing n-type and p-type impurities using ion implantation, thermal diffusion, or the like.

[0041] [Embodiment 2] Second Embodiment Next, a semiconductor optical device according to a second embodiment of the present invention will be described with reference to FIGS. 6A and 6B.

[0042] This semiconductor optical device has an optical waveguide structure with an active layer 104 formed on a substrate 101 as a core. The optical waveguide structure includes a laser region 131a made of a distributed feedback laser and a modulation region 132 made of an electroabsorption modulator disposed contiguous with the laser region 131a. This semiconductor optical device is a well-known EA-DFB laser. Note that Figure 6A shows a cross section of a plane perpendicular to the surface of the substrate 101 and parallel to the waveguiding direction.

[0043] In this semiconductor optical device, the active layer 104 in the modulation region 132 is composed of a plurality of well structures 104a that are periodically separated in the waveguiding direction. This configuration makes it possible to make the absorption edge wavelength of the active layer 104 in the modulation region 132 shorter than the absorption edge wavelength of the active layer 104 in the laser region 131a. The active layer 104 in the modulation region 132 has a multiple quantum well structure composed of the well structures 104a in the waveguiding direction.

[0044] A cladding layer 102 is formed on the substrate 101, and a semiconductor layer 103 is formed on the cladding layer 102. An active layer 104 is buried in the semiconductor layer 103.

[0045] In the second embodiment, the active layer 104 in the laser region 131a is composed of a structure 104c that is continuous in the waveguiding direction. In the second embodiment, the diffraction grating 105 is formed by a periodic uneven pattern formed on the upper surface of the semiconductor layer 103 in the laser region 131a, thereby forming a resonator. The diffraction grating 105 can also be formed by forming a dielectric layer made of SiO2, SiN, or the like on an InP thin film layer on the upper surface of the semiconductor layer 103 and etching this dielectric layer.

[0046] Also in the second embodiment, the active layer 104 is of a lateral current injection type and lateral voltage application type sandwiched between a p-type semiconductor layer 106 and an n-type semiconductor layer 107 in the planar direction of the substrate 101. In the modulation region 132, a first p-electrode 110 is formed on the p-type semiconductor layer 106 with a first p-type contact layer 108 interposed therebetween. In the modulation region 132, a first n-electrode 111 is formed on the n-type semiconductor layer 107 with a first n-type contact layer 109 interposed therebetween.

[0047] In the laser region 131a, a second p-electrode 114 is formed on the p-type semiconductor layer 106 with a second p-type contact layer 112 interposed therebetween. In the laser region 131a, a second n-electrode 115 is formed on the n-type semiconductor layer 107 with a second n-type contact layer 113 interposed therebetween. The active layer 104 may have a multiple quantum well structure in the thickness direction, or may have a so-called bulk structure.

[0048] The semiconductor optical device according to the second embodiment has a configuration in which the laser region 131 in the first embodiment and the laser region in the first example are replaced with a surface grating type DFB laser using a grating 105, and other configurations are the same as those of the first embodiment. The laser region 131a has an active layer 104 formed of a continuous structure 104c having a length of 100 μm in the waveguiding direction.

[0049] Furthermore, in the second embodiment, the pitch of the diffraction grating 105 at the rear end 105b of the laser region 131a is wider than that at the front end 105a on the modulation region 132 side. With this configuration, the laser region 131a operates as a refractive index coupled DFB laser, and stable single mode operation of the long wavelength stop band of the diffraction grating 105 can be achieved. Even with this structure, an integrated modulation light source using a single active layer 104 that is applicable to high speed modulation of the 50 Gbaud class can be realized.

[0050] According to the second embodiment, it is easier to control the coupling coefficient of the diffraction grating than in the first embodiment, and it is effective in, for example, ensuring stable single-mode operation by lengthening the cavity length of the laser and suppressing the value of the coupling coefficient, and in realizing high-output operation by suppressing the current density.

[0051] The active layer material can be any material that can be grown on an InP substrate, such as InGaAs, GaInNAs, InGaAsP, or InAlGaAs. While the above-described embodiment uses a thin-film structure on an SiO2 / Si substrate to achieve high optical confinement within the active layer, a similar structure can also be formed on an InP substrate. The modulation region can naturally function as a standalone modulator, and can also be applied to integrated optical circuits such as gate elements.

[0052] As described above, according to the present invention, the active layer of the modulation region is constructed from a plurality of well structures periodically separated in the waveguiding direction, which makes it possible to easily manufacture semiconductor optical devices such as EA-DFB lasers.

[0053] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention.

[0054] [Reference] K. Ohira et al, "Low-Threshold and High-Efficiency Operation of Distributed Reflector Lasers With Width-Modulated Wirelike Active Regions", IEEE Journal of Selected Topics in Quantum Electronics, vol. 11, no. 5, pp. 1162-1168, 2005. [Explanation of symbols]

[0055] 101...substrate, 102...cladding layer, 103...semiconductor layer, 104...active layer, 104a...well structure, 104b...well structure, 105...diffraction grating, 106...p-type semiconductor layer, 107...n-type semiconductor layer, 108...first p-type contact layer, 109...first n-type contact layer, 110...first p-electrode, 111...first n-electrode, 112...second p-type contact layer, 113...second n-type contact layer, 114...second p-electrode, 115...second n-electrode, 131...laser region, 132...modulation region.

Claims

1. an optical waveguide structure having an active layer formed on a substrate as a core; The optical waveguide structure includes: a laser region consisting of a distributed feedback laser; a modulation region consisting of an electroabsorption modulator disposed contiguous with the laser region; Equipped with The active layer in the modulation region is composed of a plurality of well structures periodically separated in the waveguiding direction so that the absorption edge wavelength of the active layer in the modulation region is shorter than the absorption edge wavelength of the active layer in the laser region. A semiconductor optical device characterized by:

2. 2. The semiconductor optical device according to claim 1, 10. A semiconductor optical device, comprising: an active layer in the laser region, the active layer comprising a plurality of well structures periodically separated in the waveguiding direction;

3. 3. The semiconductor optical device according to claim 2, A semiconductor optical device, characterized in that the resonator of the laser region is composed of a diffraction grating formed by the active layer which is composed of a plurality of well structures periodically separated in the waveguiding direction.

4. The semiconductor optical device according to any one of claims 1 to 3, the laser region is of a lateral current injection type; The modulation area is of a lateral voltage application type. A semiconductor optical device characterized by:

Images