EP0000557B1 - Halbleiterlaser - Google Patents

Halbleiterlaser Download PDF

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Publication number
EP0000557B1
EP0000557B1 EP78100461A EP78100461A EP0000557B1 EP 0000557 B1 EP0000557 B1 EP 0000557B1 EP 78100461 A EP78100461 A EP 78100461A EP 78100461 A EP78100461 A EP 78100461A EP 0000557 B1 EP0000557 B1 EP 0000557B1
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Prior art keywords
semiconductor layer
semiconductor
laser device
layer
region
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EP78100461A
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English (en)
French (fr)
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EP0000557A1 (de
Inventor
Michiharu Nakamura
Shigeo Yamashita
Takao Kuroda
Junichi Umeda
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Hitachi Ltd
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Hitachi Ltd
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Priority claimed from JP9136877A external-priority patent/JPS5427385A/ja
Priority claimed from JP3691278U external-priority patent/JPS54141881U/ja
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/12—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
    • H01S5/22—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers having a ridge or stripe structure
    • H01S5/223—Buried stripe structure
    • H01S5/2232—Buried stripe structure with inner confining structure between the active layer and the lower electrode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
    • H01S5/22—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers having a ridge or stripe structure
    • H01S5/223—Buried stripe structure
    • H01S5/2232—Buried stripe structure with inner confining structure between the active layer and the lower electrode
    • H01S5/2234—Buried stripe structure with inner confining structure between the active layer and the lower electrode having a structured substrate surface

Definitions

  • This invention relates to a semiconductor laser device with a first semiconductor layer and with a second and a third semiconductor layer which sandwich said first semiconductor layer therebetween, which are greater in the band gap and lower in the refractive index than said first semiconductor layer and which have conductivity types opposite to each other, with a fourth semiconductor layer rendering the effective complex refractive index for the laser beam discontinuous in a direction perpendicular to the travelling direction of the laser beam, and with periodic corrugations formed in at least one interface of the semiconductor layers constituting an optical wave guide of said semiconductor laser device in a manner to intersect orthogonally to said travelling direction of the laser beam.
  • Semiconductor laser devices have many merits, such as small size, operation at high efficiency, and capability of direct modulation by a drive current. They are therefore hopeful as light sources for optical communication, optical information processing, etc.
  • a distributed-feedback semiconductor laser device having the above features is known from U.S. patent specification 4 023 993.
  • Such a distributed-feedback semiconductor laser achieves mode stabilization by exploiting the sharp oscillation mode selectivity which is produced by the light diffraction effect based on the corrugated surface.
  • Figs. 1 and 2 of the accompanying drawing show an example of the distributed-feedback semiconductor laser device.
  • Fig. 1 is a sectional view taken orthogonally to the travelling direction of light
  • Fig. 2 is a sectional view taken along the travelling direction of light.
  • numeral 1 designates an n-GaAs substrate
  • numeral 2 an n-Ga,_ x Al x As layer (x ⁇ 0.3)
  • numeral 3 a GaAs active layer
  • numeral 4 a p-Ga 1-x AI x As layer and numeral 5 periodic corrugations which are provided at the boundary between the active layer 3 and the semiconductor layer 4.
  • Numerals 6 and 7 indicate ohmic electrodes.
  • the layers 2, 3 and 4 constitute an optical waveguide. Light given forth in active layer 3 is guided centering around the active layer 3, and is subjected to the Bragg reflection of 180° by the periodic corrugations 5 formed at the boundary between the layers 3 and 4.
  • the distributed-feedback semiconductor laser device oscillates at a single longitudinal mode and exhibits a spectral width of 0.05 mm (0.5 A) or less, so that it is excellent in monochromaticity. In addition, the temperature-dependency of the oscillation wavelength is low.
  • This invention has for its object to provide a novel semiconductor laser device in which a longitudinal and transverse mode is stabilized singly and in which any excess optical noise component for a modulated signal is not generated by mode competition.
  • the semiconductor laser device of the type initially referred to is characterized, in accordance with the present invention, in that said second and/or said third semiconductor layer have a protuberant region or are bordered on their side remote from said first semiconductor layer by a fifth semiconductor layer with a protuberant region, that said protuberant region having a width able to stabilize a transverse mode of the laser oscillation extends in said-travelling direction of the laser beam and has the shape of a stripe on its surface side remote from said first semiconductor layer, that said fourth semiconductor layer has portions on both sides of said protuberant region, and that said periodic corrugations are formed to include at least a region overlying said protuberant region.
  • a semiconductor laser which is equipped with a first semiconductor layer and with a second and a third semiconductor layer which sandwich the first semiconductor layer therebetween, said second semiconductor layer having a protuberant region on both sides of which a semiconductor layer is disposed.
  • the protuberant region extends in the travelling direction of the laser beam and has the shape of a stripe on its surface side remote from the first semiconductor layer.
  • the protuberant region is used to confine the current through the active layer.
  • a semiconductor laser device which is equipped with a first semiconductor layer and with a second and third semiconductor layer which sandwich said first semiconductor layer therebetween, with a semiconductor layer rendering the effective complex refractive index for the laser beam discontinuous in a direction perpendicular to the travelling direction of the laser beam, and with a substrate having an elongated groove extending in the travelling direction of the laser beam through a pump current confining layer, a central portion of the first semiconductor layer being bowl-shaped.
  • This structure is used to adapt the cross section of the emitted laser beam to round lenses.
  • FIG. 3 is a perspec - tive view of the typical example of this invention.
  • the upper surface of the p-Ga 1-y Al y As layer 4 is formed" with periodic corrugations 8.
  • Numerals 6 and 7 designate ohmic electrodes.
  • the light generated in the active layer 3 is confined in the vertical direction around the active layer by the double-heterostructure. Part of the light evanesces to the GaAIAs layers 2 and 4 on both the sides.
  • the light having evanesced to the N-Ga 1-x Al x As layer 2 reaches the GaAs substrate 1 in regions on both the sides of the groove 9 because the n-Ga 1-x Al x As layer 2 in these regions is thin.
  • the complex refractive-index for the light becomes different between the region corresponding to the groove 9 and the regions corresponding to both the sides of the groove 9. For this reason, any higher-order mode oscillation spreading to outside of the groove and the deviation of the oscillation region are suppressed, and the effect that the light is stably confined only to the region of the groove 9 in the lateral direction is produced.
  • the travelling direction of the light is taken in the z-direction.
  • the laser light is diffracted, and where ⁇ : wavelength of the light, n : effective refractive index of waveguide. A: period of the corrugations and I: order of the diffraction.
  • the width of the stripe-shaped light non-absorptive protuberant region corresponding substantially to the radiation region is made 2 ⁇ m to 8 ⁇ m. With widths below 2 ⁇ m; especially the threshold current density (the lowest current density necessary for attaining the laser oscillation) increases rapidly. With widths above 8 ⁇ m, especially the instability of the transverse mode increases.
  • the quantity of evanescence of the light to the regions which exist on both sides of the light non-absorptive protuberant region and which make the complex refractive index for the laser beam discontinuous at least 3 x 10 -2 % of the whole quantity of the light, preferably 5 x 10- 2 % to 5 x 10 -1 % of the same is appropriate.
  • in both the regions is preferably made 10- 3 to 10- 2 .
  • the thickness d of the active layer 3 and the thickness t of the n-Ga 1-x Al x As layer 2 need to be selected.
  • the thickness of the active layer is ordinarily set at 0.05 ⁇ m to 0.15 ⁇ m.
  • the thickness d of the active layer is 0.1 ⁇ m, it is favorable to make the thickness t at most 0.5 ⁇ m; when the thickness d is 0.15 ⁇ m, it is favorable to make the thickness t at most 0.2 ⁇ m; when the thickness d is 0.05 ⁇ m, it is favorable to make the thickness t at most 0.7 ⁇ m.
  • the thickness of the semiconductor layer 2 may be set by the interpolation with the aforecited values.
  • the distance c between the active layer 3 and the periodic corrugations 8 which are provided at the interface between the semiconductor layers 4 and 5 is made at most 1 ⁇ m, preferably at most 0.5 um, and at least 0.03 ⁇ m.
  • the distance c is below 0.03 ⁇ m, the carrier confinement effect owing to the p-Ga 1-y AI y As layer 4 becomes insufficient, and an increase of the threshold current density is incurred.
  • the distance c is above 1 ⁇ m, the degree to which the radiation in the active layer senses the periodic corrugations decreases abruptly, so that the laser oscillation of the distributed feedback type does not take place.
  • the depth L of the corrugations is desirably selected in a range of 0.01 ⁇ m to 0.5 ,um.
  • the depth L is less than 0.01 ⁇ m, the Bragg reflection of the light owing to the periodic corrugation structure becomes insufficient, and the laser oscillation of the distributed feedback type becomes difficult.
  • the semiconductor layer corresponding to the semiconductor substrate 1 in Fig. 3 may consist of a plurality of layers. It is also allowed to form a separate semiconductor layer on the semiconductor substrate and to provide a recess in the separate semiconductor layer, the recess being used as the groove 9 in Fig. 3. The purpose can be achieved even when a discontinuity in only the refractive index (corresponding to the real part of the complex refractive index) is produced. In any case, however, the technical items previously described may be conformed with.
  • a GaAsGaAIAs conductor will be referred to as a semiconductive material
  • the present invention concerns the property of a laser resonator including an optical waveguide and that it is independent of materials.
  • This invention is accordingly applicable, not only to semiconductor lasers employing the above-mentioned semiconductor, but also to semiconductor lasers employing e.g. a ternary system compound semiconductor such as GalnP, GaAsP and GaAISb and a quaternary system compound semiconductor such as GalnAsP and GaAIAsSb.
  • n-GaAs substrate 1 Te-doped, electron concentration n 1 x 10 18 /cm 3
  • a groove 9 having a depth of 1.5 ⁇ m and a desired width in the range of 2 ⁇ m to 8 ⁇ m was formed in the (011) orientation.
  • the conventional photolithography may be employed.
  • photoresist was directly used as an etching mask. The chemical etching was conducted at 20°C for about 140 seconds with a mixed solution which contained phosphoric acid, hydrogen peroxide solution and ethylene glycol at 1:1:3.
  • GaAlAs system material it is common to employ Ga 1-z Al z As (0 5 z ⁇ 0.3) for the first semiconductor layer, Ga 1-x Al x As (0.1 ⁇ x ⁇ 0.9) for the second semiconductor layer and Ga 1-y Al y As (0.1 ⁇ y ⁇ 0.9) for the third semiconductor layer, where x, y, > z; r > z; and y ⁇ r.
  • corrugations 8 having a period of 370 nm (3 700 A) and a depth of 150 nm (1 500 A) were formed in the surface of the p-Ga 1-y Al y As layer 4.
  • holographic photolithography employing a laser beam and chemical etching were used. More specifically, a' film of the positive type photoresist as was 80 nm (800 A) thick was formed on the surface of the semiconductor layer 4. Subsequently, using an Ar laser at a wavelength of 457.9 nm (4 579 A), an interference fringe was formed on the photoresist. After completing exposure, development was carried out for about 1 min with a mixed solution consisting of a developer and water at 1:1.
  • a diffraction grating made of a photoresist was formed.
  • the diffraction grating made of the photoresist was used as a mask, and a mixed solution consisting of phosphoric acid, a solution of hydrogen peroxide and ethylene glycol at 1:1:8 was used as an etchant.
  • Periodic corrugations 8 having a depth of 0.15 ⁇ m were formed by the etching at 20°C for 80 seconds. This method is disclosed in Japanese Laid-Open Patent Application No. 111344/1976.
  • a p-Ga 1- ⁇ Al ⁇ As layer 5 as the sixth semiconductor layer ( ⁇ 0.1 and in general, 0.05 ⁇ ⁇ 0.09; hole concentration p - 5 x 10 17 cm -3 ) was formed to a thickness of 2.0 ⁇ m by employing the conventional liquid-phase epitaxial growth again.
  • Zn was diffused into a desired region of the p-side surface of the specimen thus formed, whereupon Cr and Au were deposited by vacuum-evaporation so as to form an electrode.
  • the substrate side was lapped down to about 150 ⁇ m, whereupon Au-Ge-Ni was brought into close contact to form an electrode.
  • the laser length was made 300 ⁇ m.
  • the width W of the groove 9, the distance t of the active region from the light absorptive region, the thickness d of the active layer 3, the distance C between the active layer and the periodic corrugations, the depth L of the periodic corrugations, etc. have influence on the oscillation characteristics.
  • Fig. 4 shows the characteristics of semiconductor lasers employing various combinations between the width W of the groove 9 and the distance t of the active region from the light absorptive region. While values of 0.05 ⁇ m to 0.15 ⁇ m are often employed as the thickness d of the active layer 3, a value of 0.1 pm is given as a typical example.
  • the depth L of the periodic corrugations is 150 ⁇ m (1 500 A).
  • Mark 0 indicates an example in which the laser device oscillated in a single mode longitudinally and transversely without any optical noise
  • mark A an example in which the laser device oscillated in a single longitudinal mode, but excess optical noise was generated by mode competition
  • mark X an example in which the laser device did not reach the continuous oscillation on account of the increase of the threshold current density.
  • the width W of the groove 9 capable of achieving the object is 2 ⁇ m to 8 ⁇ m.
  • a value of 0.05 ⁇ m or less is the limit to which the layer can be stably fabricated in the actual process, while a value of 0.45 ⁇ m or greater falls in a region in which a desired light absorption was not attainable.
  • Figs. 5 to 8 illustrate the states of generation of excess optical noise attributed to mode competition.
  • a square wave signal current having a pulse width of 8 ns, a pulse height of 160 mA (1.25 times a threshold value) and a recurrence frequency of 62.5 MHz was caused to flow through a semiconductor laser device having a threshold current of 130 mA, and the optical output of the semiconductor laser was observed.
  • the optical output waveform is a result obtained by conversion into an electric signal with a photodiode of which the wavelength band was the oscillation wavelength ⁇ 0.1 nm ( ⁇ 1 A) and the frequency band was 1 MHz to 0.8 GHz.
  • FIG. 5 shows an example of the optical output waveform of the distributed-feedback semiconductor laser device exemplified in Fig. 1.
  • Fig. 6 shows an example of the optical output waveform of a prior art buried heterostructure semiconductor laser device
  • Fig. 7 shows an example of the optical output waveform of the semiconductor laser device of this invention
  • Fig. 8 shows an example of the optical output waveform of a semiconductor laser device which has a a structure similar to that of this invention but whose stripe-shaped non-absorptive region is as broad as 12 ⁇ m. It is apprehended from the observation of the optical output waveforms that the semiconductor laser device of this invention is excellent.
  • the semiconductor laser device of the structure of this example is advantageous in that the deterioration is especially little and that the transverse mode is more easily stabilized. This originates in that the periodic corrugations can be formed after forming the active layer.
  • n-GaAs substrate 21 Te-doped, electron concentration n n ⁇ 1 x 10 18 /cm 3 ) having the (100) face as its surface
  • a groove 29 having a depth of about 1.5 ⁇ m and a desired width in a range of 2 ⁇ m to.8 ⁇ m was formed by the conventional photolithography and chemical etching.
  • Photoresist was used for an etching mask.
  • the chemical etching was conducted at 20°C for about 140 seconds with a mixed solution which consisted of phosphoric acid, hydrogen peroxide solution and ethylene glycol at 1:1:3.
  • the surface of the grown layer was subjected to the chemical etching until the substrate 21 was exposed on both sides of the groove.
  • the chemical etching was carried out at 20°C for about 70 seconds by the use of phosphoric acid, hydrogen peroxide solution and ethylene glycol at 1:1:3.
  • corrugations 28 having a period of 375 nm (3 750 A) were formed in the direction orthogonal to the groove (in the (011) orientation) by the holographic photolithography employing a laser beam and the chemical etching.
  • photoresist being about 80 nm (800 A) thick was used.
  • a mixed solution consisting of phosphoric acid, a solution of hydrogen peroxide and ethylene glycol at 1:1:8 was employed as at etchant, and the etching was conducted at 20°C for 80 seconds.
  • the corrugations 28 being 0.15 pm deep were formed in the crystal surface.
  • an n-Ga 1-x Al x As layer 22 (x ⁇ 0.3; Sn-doped; electron concentration n - 5 x 10" cm- 3 ) being 0.4 um thick
  • the AI contents of the respective layers must be so set that, with respect to light produced in the active layer 23, the substrate 21 becomes an absorptive region, while the stripe-shaped buried n-Ga 1-s Al s As layer 30 becomes a non-absorptive region.
  • the composition ratio between the n-Ga 1-s Al s As layer 30 and the Ga 1-z Al z As active layer 23 is made z ⁇ s, and it is desirable that (s-z) is approximately 0.01 or greater.
  • the AI content s of the n-Ga 1-s Al s As layer 30 may, in principle, be made 0.01 ⁇ s ⁇ 0.9.
  • s ⁇ 0.1 must be held in order that the crystal may be smoothly grown on this layer by the liquid-phase epitaxial growth generally employed.
  • s > 0.1 the normal liquid-phase growth becomes difficult in practice.
  • Zn was diffused into the p-side surface of this specimen by approximately 0.1 pm, whereupon Cr and Au were deposited by vacuum-evaporation so as to form an electrode 27.
  • the substrate side was lapped down to approximately 150 ⁇ m, whereupon Au-Ge-Ni was evaporated to form an ohmic electrode 26.
  • Fig. 11 is a graph showing the light output versus current characteristics of this embodiment, while Fig. 12 is a graph showing the far-field intensity distributions in the junction plane.
  • the results were obtained in an example in which the semiconductor laser device had a length of 300 ⁇ m and a groove width of 7 ⁇ m.
  • the threshold current value was 100 mA at room temperature, and the external differential quantum efficiency was about 35%.
  • Fig. 11 corresponds to the light output versus current characteristics at this time.
  • the laser oscillated in the fundamental transverse mode, and the transverse mode was stable up to above double the threshold value.
  • Fig. 13 shows the lasing spectra of the embodiment.
  • the oscillation arose at a wavelength of 836 nm (8 360 A), and even when the current value was increased double the threshold value, no change was noted.
  • Fi. 14 shows the pulse responses at the time when current pulses having a width of 7 ns were impressed on the present laser device. Since the transverse mode was stabilized,ste relaxation oscillation to become an optical noise as observed in the prior art distributed-feedback semiconductor laser was not noted.
  • Fig. 15 concerns another embodiment of this invention, and is a sectional view taken perpendicularly to the travelling direction of light within a laser.
  • corrugations 28 were formed on only the surface of the fifth semiconductor layer 30 grown in a groove.
  • the other features were the same as in the case of Fig. 9.
  • the feedback of light owing to the diffraction effect is selectively attained only in the upper part of the groove, and the lasing occurs concentratedly in this part. Therefore, the transverse mode is further stabilized.
  • the thickness of the active layer 23 was 0.1 ⁇ m and where the thickness of the second semiconductor layer 22 was 0.3 pm
  • the laser oscillated in the fundamental transverse mode up to triple the threshold value. Any excess optical noise for a modulated signal at the time of modulation as otherwise generated by mode competition was not noted.
  • Fig. 16 is a sectional view showing another embodiment of this invention.
  • an n-Ga 1-y Al y As layer 33 as the fifth semiconductor layer was grown on the whole surface of an n-GaAs substrate 21 in a manner to fill up the groove of the substrate, and corrugations 34 were formed thereon.
  • the other features were the same as in Example 1.
  • the sum of the thickness of the layer 33 and the layer 22 needed to be made 0.6 ⁇ m or less when the thickness of the active layer was 0.1 ⁇ m.
  • the thickness of the fifth semiconductor layer 33 outside the groove was 0.2 pm
  • the thickness of the second semiconductor layer 22 was 0.2 pm
  • the thickness of the active layer was 0.1 ⁇ m
  • the groove width was 7 ⁇ m and the length was 300 ⁇ m
  • the threshold current value of the oscillation was 100 mA and each of the longitudinal and transverse modes was single and stable up to above double the threshold value.
  • a layer overlying an active layer is formed with periodic corrugations, whereupon a layer is formed which is provided with a protuberance corresponding substantially to a radiation portion.
  • the protuberant layer is made a light non-absorptive layer.
  • a layer serving as a light absorptive layer is formed.

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
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  • Optics & Photonics (AREA)
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  • Semiconductor Lasers (AREA)

Claims (12)

1. Halbleiterlaser mit einer ersten (3; 23), einer zweiten (2; 22) und einer dritten (4; 24) Schicht aus Halbleitermaterial, wobei die zweite und die dritte Schicht die erste Schicht sandwichartig einschließen, einen größeren Bandabstand sowie einen geringeren Brechungsindex als die erste Schicht haben und jeweils einen zueinander entgegengesetzten Leitfähigkeitstyp aufweisen, mit einer vierten Schicht (1; 21) aus Halbleitermaterial, welche den effektiven komplexen Brechungsindex für den Laserstrahl diskontinuierlich macht in Bezug auf eine zur Ausbreitungsrichtung des Laserstrahls senkrechte Richtung, und mit periodischen Wellungen (8; 28; 34), die an wenigstens einer Grenzfläche der Schichten aus Halbleitermaterial ausgebildet sind und einen die Ausbreitungsrichtung des Laserstrahls orthogonal schneidenden optischen Wellenleiter des Halbleiterlasers bilden, dadurch gekennzeichnet, daß die zweite (2; 22) und/oder die dritte Schicht (4; 24) eine vorspringende Zone (bei 9 in Figur 3) aufweisen, oder an der von der ersten Schicht (1; 21) abgewandten Seite durch eine fünfte Schicht (30; 33) aus Halbleitermaterial mit einer vorspringenden Zone versehen sind, wobei die vorspringende Zone eine zur Stabilisierung des transversalen Schwingungsmodus der Laserschwingungen geeignete Weite hat, sich in Ausbreitungsrichtung des Laserstrahls erstreckt und an der von der ersten Schicht abgewandten Seite die Gestalt eines Bandes hat, daß die vierte Schicht (1; 21) Anteile zu beiden Seiten der vorspringenden Zone aufweist, und daß die periodischen Wellungen (8; 28; 34) wenigstens ein die vorspringende Zone bedeckendes Gebiet aufweisen.
2. Halbleiterlaser nach Anspruch 1, dadurch gekennzeichnet, daß die vorspringende Zone von der zweiten (2) oder von der dritten (4) Schicht aus Halbleitermaterial gegeben wird, daß die keine vorspringende Zone aufweisende dritte bzw. zweite Schicht aus Halbleitermaterial mit den periodischen Wellungen (8) an der von der ersten Halbleiterschicht (3) entfernt liegenden Oberfläche versehen ist, und daß eine sechste Schicht (5) aus Halbleitermaterial auf der Oberfläche der periodischen Wellungen angeordnet ist (Fig. 3).
3. Halbleiterlaser nach Anspruch 1, dadurch gekennzeichnet, daß die periodischen Wellungen (28) an der jeweiligen Grenzfläche der zweiten (22) und/oder der dritten (24) Schicht aus Halbleitermaterial mit der sie bedeckenden fünften Halbleiterschicht (30) oder auch der sie bedeckenden vierten Halbleiterschicht (21) ausgebildet sind (Fig. 9, 10; 14).
4. Halbleiterlaser nach Anspruch 1, dadurch gekennzeichnet, daß die fünfte Halbleiterschicht (30) die vorspringende Zone aufweist und daß die periodischen Wellungen (34) an einer Grenzfläche der zweiten (22) und/oder dritten (24) Halbleiterschicht mit der bedeckenden fünften Halbleiterschicht ausgebildet sind (Fig. 16).
5. Halbleiterlaser nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß der Absolutwert der Differenz zwischen den effektiven komplexen, für den Laserstrahl diskontinuierlichen Brechungsindizes zwischen 10-3 und 10-2 beträgt.
6. Halbleiterlaser nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß die Weite der vorspringenden Zone (33) oder der fünften Halbleiterschicht (30) zwischen 2 µm und 8 µm beträgt und daß der Abstand zwischen der ersten Halbleiterschicht (3; 23) und den periodischen Wellungen (8; 28; 34) zwischen 0,03 am und 1 µm beträgt.
7. Halbleiterlaser nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß die Dicke der ersten Halbleiterschicht (3; 23) zwischen 0,05 µm und 0,15 µm beträgt.
8. Halbleiterlaser nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, daß die vierte Halbleiterschicht (1; 21) aus einem Halbleitersubstrat besteht, das eine Nut (9; 29) aufweist, welche sich in Ausbreitungsrichtung des Laserstrahls in der Gestalt eines Bandes erstreckt.
9. Halbleiterlaser nach Anspruch 2 und 8, dadurch gekennzeichnet, daß das Halbleitersubstrat (1) aus GaAs, die erste Halbleiterschicht (3) aus Ga1-zAlzAs (mit 0 ≦ z ≦ 0,3), die zweite Schicht (2) aus Ga1-xAlxAs (0,1 ≦ x ≦ 0,9), die dritte Schicht (4) aus Ga1-yAlyAs (0,1 ≦ y ≦ 0,9) und die sechste Schicht (5) aus Ga1-νAlνAs (0,05 < ν < 0,9) bestehen, wobei x, y > z und y ≠ γ ist (Fig. 3)
10. Halbleiterlaser nach Anspruch 3 und 8, dadurch gekennzeichnet, daß das Halbleitersubstrat (21) ein GaAs-Substrat ist, daß die erste Schicht (23) aus Ga1-zAlzAs (0 < z ≦ 0,3), die zweite Schicht (22) aus Ga1-xAlxAs (0,1 ≦ x≤ 0,9), die dritte Schicht (24) aus Ga1-yAlvAs (0,1≦ y≦ 0,9) und die fünfte Schicht (30) aus Ga1-sAlsAs (0,01 ≦ s ≤ 0,9) bestehen, wobei x, y > z, s > z und x ≠ s ist (Fig. 9, 10, 15).
11. Halbleiterlaser nach Anspruch 4 und 8, dadurch gekennzeichnet, daß das Halbleitersubstrat (21) aus GaAs, die erste Schicht (23) aus Ga1-zAlzAs (0 ≤ z ≤ 0,3), die zweite Schicht (22) aus Ga1-xAlxAs (0,1 ≦ x ≤ 0,9), die dritte Schicht (24) aus Ga1-yAlys (0,1 ≢ y≦ 0,9), und die fünfte Schicht (33) aus Ga1-yAly As (0,1 ≦γ ≦ 0,9) besteht, wobei x, y > z, γ > z und x ≠ γ (Fig. 16).
EP78100461A 1977-08-01 1978-07-20 Halbleiterlaser Expired EP0000557B1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP91368/77 1977-08-01
JP9136877A JPS5427385A (en) 1977-08-01 1977-08-01 Semiconductor laser
JP3691278U JPS54141881U (de) 1978-03-24 1978-03-24
JP36912/78U 1978-03-24

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EP0000557A1 EP0000557A1 (de) 1979-02-07
EP0000557B1 true EP0000557B1 (de) 1981-12-30

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JPS59205787A (ja) * 1983-05-09 1984-11-21 Nec Corp 単一軸モ−ド半導体レ−ザ
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EP0000557A1 (de) 1979-02-07
CA1105598A (en) 1981-07-21
DE2861465D1 (en) 1982-02-18
US4257011A (en) 1981-03-17

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