GB2384617A - Semiconductor laser diodes - Google Patents

Semiconductor laser diodes Download PDF

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GB2384617A
GB2384617A GB0124715A GB0124715A GB2384617A GB 2384617 A GB2384617 A GB 2384617A GB 0124715 A GB0124715 A GB 0124715A GB 0124715 A GB0124715 A GB 0124715A GB 2384617 A GB2384617 A GB 2384617A
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triangular
contact
layer
waveguiding
tdi
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Wang Nang Wang
Yury Georgievich Shreter
Yury Toomasovich Rebane
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ARIMA OPTOELECTRONIC
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ARIMA OPTOELECTRONIC
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
    • G01C19/58—Turn-sensitive devices without moving masses
    • G01C19/64—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams
    • G01C19/72—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers
    • G01C19/721—Details
    • 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
    • H01S5/1071—Ring-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
    • H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
    • H01S5/042—Electrical excitation ; Circuits therefor
    • H01S5/0425—Electrodes, e.g. characterised by the structure
    • H01S5/04254—Electrodes, e.g. characterised by the structure characterised by the shape
    • 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
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/32—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures
    • H01S5/323—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser
    • H01S5/32308—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser emitting light at a wavelength less than 900 nm
    • H01S5/32341—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser emitting light at a wavelength less than 900 nm blue laser based on GaN or GaP
    • 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
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/32—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures
    • H01S5/323—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser
    • H01S5/3235—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser emitting light at a wavelength longer than 1000 nm, e.g. InP-based 1300 nm and 1500 nm 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
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/32—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures
    • H01S5/327—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures in AIIBVI compounds, e.g. ZnCdSe-laser

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Optics & Photonics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Power Engineering (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Semiconductor Lasers (AREA)

Abstract

Semiconductor laser diodes are described, having triangular or truncated triangular cavities in the form of mesas 3 for the lateral confinement of radiation, based on III-V or II-VI semiconductor compounds. Spatially distributed current injection is used for selective excitation of the chosen optical modes within the cavities. The current injection system comprises a single lower electrode 1 and a multi-contact upper electrode 4, where contact spots (see figs 1-5) coincide with maxima of intensity for optical modes of the cavity which are chosen for selective pumping. Lasers having triangular cavities with distributed injection (TDI diodes) allow a single mode, or controlled multi-mode laser output, with high quality factor suitable for such applications as CD and DVD pick-up heads, laser printers and telecommunications. To lower the threshold current and increase laser power, optically connected arrays of triangular cavities are described (figs. 3-5). A TDI matrix suitable for laser gyroscope applications is described (fig. 5).

Description

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SEMICONDUCTOR LASER DIODES BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to laser diodes. More particularly, the invention relates to laser diodes with a triangular or truncated triangular optical cavity based on in-V or II-VI semiconductor compounds or their alloys.
2. Description of the Prior Art Semiconductor laser diodes with various shapes of laser cavities, such as micro-disk, micro-are-ring, triangular ridge, L-shaped ridge, U-shaped ridge and bow-tie lasers, are known. Recently a semiconductor laser device with an equilateral triangle resonance cavity composed of an ordinary lateral-emitting laser device and a flat waveguide consisting of a lower limit layer, an active region and an upper limit layer has been suggested (CN1267106). Its advantages are simple structure, easy implementation, uniformly distributed light field in the equilateral triangle optical cavity, high directivity of laser radiation and small size. The advantages of the uniformly distributed light field in the equilateral triangle optical cavity are related to the easiness of laser pumping by uniformly distributed current and the effective use of the whole volume of the equilateral triangle optical cavity for light generation.
However, there is also a significant drawback in the generation of a uniformly distributed light field in such an equilateral triangle optical cavity, related to the uncontrollable generation of a great number of optical modes which are characteristic of this type of resonator-see H. C. Chang, et al. Phys. Rev. A, Vol. 62,13816, (2000).
Meanwhile, many applications require a single mode or controllable multi-mode laser operation.
The present invention provides semiconductor lasers diodes and arrays or matrixes of them having a triangular or truncated triangular cavity with spatially distributed current injection (TDI), which can operate in a single mode or controllable multi-mode regimes.
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SUMMARY OF THE INVENTION This invention provides a semiconductor laser diode having a triangular or truncated triangular optical cavity with spatially distributed current injection (TDI), and TDI semiconductor laser diode arrays or matrixes (by way of example Figs. 1-5 below).
The active layer of a TDI semiconductor laser can be made of a III-V or II-VI semiconductor double heterostructure, single quantum well or multiple quantum wells or current asymmetric resonance tunnelling structure (see e. g. GB 2 352 326).
The optical cavity of a TDI semiconductor laser diode can be made of a lateral waveguide comprising a III-V or II-VI semiconductor heterostructure or double heterostructure or index-graded structure or superlattice structure or another waveguide structure for vertical light confinement and a triangular (e. g. Fig. 1) or truncated triangular (e. g. Fig. 2) mesa structure for lateral confinement of light.
The spatially distributed current injection system of a TDI semiconductor laser diode can comprise a lower uniform single-contact electrode and an upper multi-contact electrode (e. g. Figs. 1-5). The contact spots of the upper electrode coincide with maxima of intensity for optical modes of the triangular cavity chosen for selective pumping. Thus, the number of contact spots (Nspot) should be equal to the number of intensity maxima (Nmax) for the optical mode chosen for selective pumping.
A =7as (1) The modes in a triangular cavity can be characterized by the lateral quantum number n, and longitudinal quantum number m, which are both even or odd, and n g m,-see, H. C.
Chang, et al. Phys. Rev. A, Vol. 62, 13816, (2000).
The corresponding wavelength is given by the equation = 3an cos A +/ (2)
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where a is the length of the triangular cavity side, nr is the refractive index of the semiconductor waveguiding layer and zizis the effective propagating angle for light rays inside the planar waveguide-see H.-G. Unger,"Planar optical wave guides and fibres", Clarendon Press, Oxford, 1977, Fig. 6.
In simple planar waveguides made of double heterostructures or index-graded structures, z < < Ti/2, cos/1 and the size a of the triangular cavity for small quantum numbers n
and m should be comparable with the light wavelength A.
In complex planar waveguides having superlattice mirrors with high reflectivity, / Tt/2, co < < 1 and the size a of the triangular cavity for small quantum numbers n and m can be made much larger than the light wavelength #.
The lowest mode with n =1 and m =3 has a single maximum of optical field intensity inside a triangular cavity (e. g. Fig. 7). The corresponding upper electrode for TDI should consist of a single contact spot at the centre of the triangle, Spot= 1.
The shapes of the contact spots may vary depending on the needed degree of optical mode selectivity which is determined by the chosen cut-off level Le of the optical field intensity for a given mode.
Fig. 8 shows shapes of the upper electrode in the cases Le =0.1, Le =0.5 and Le =0.9 respectively, for the lowest mode with n =1 and m =3.
With increase of longitudinal and lateral quantum numbers m and n, the number of maxima of optical field intensity increases (see Figs. 9,12, 15,18, 22,25) and, accordingly, the number of contact spots (Figs. 11,14, 17,20, 21) should be increased for selective excitation of the given optical mode.
For optical modes with large quantum numbers the number of contact spots also depends on the chosen cut-off level L,.
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For example, for a mode with n=1, m=11, with an optical field distribution as shown in Figs. 18,19, the calculated number of contact spots is three for L, =0. 9 (Fig. 19), six for Lu0. 7 (Fig. 20) and twelve forL, =0. 5 (Fig. 21).
Also, for large n and m, because of the large number of optical field maxima, it is technologically easier to associate one contact spot with a group of optical field maxima.
Thus, for large n and m the reduced number of contact spots N is
where Ngroup is the number of the optical field maxima in the group corresponding to one contact spot.
For example, for an optical mode with n=2, m=14, with an optical field distribution as shown in Figs. 22, 23, Nmz =12 at Lue=0 5-0 9 and for Ngroup = 3 Eq. (3) gives 4, the corresponding shapes of the upper electrode being shown in Fig. 24.
For an optical mode with n=3, m=21, with an optical field distribution as shown in Figs.
25,26, Nma, =27 at Lc==0. 5-0.9 and for Ngroup = 3 Eq. (3) gives pot = 9, the corresponding shapes of the upper electrode being shown in Fig. 27.
Eq. (3) is valid for a constant number of optical field maxima in the group corresponding to one contact spot Ngroup = const.
Sometimes, it can be technologically easier to use a variable number of optical field maxima in the group corresponding to one contact spot Ngroup (i), where i is the index numerating the contact spots. In this case the Eq. (3) should be modified as
For example, for an optical mode with n=l, m=21, with an optical field distribution as shown in Figs. 28,29, Nmax =34 at Lc=0. 5, (Fig. 30) and for Ngroup (i) = 3, for i=1, 2,3,
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Ngroup (i) = 5, for i=4, 5, 6 and Ngroup (i) = 10, for i=7, Eq. (4) gives 34 = 3x3+3x5+lxlO, the corresponding shape of the upper electrode being shown in Fig. 31.
In the limiting case Ngroup='Amm, the TDI electrode can have a single contact spot as is shown in Fig. 32 for the case of an optical mode with n=1, m=21, The optical mode selectivity of a TDI electrode with a reduced number of contact spots for Ngroup > 1 is lower than that of the TDI for Ngroup= 1.
However, in combination with optical mode selectivity related to gain spectrum and quality factor, a reduced TDI electrode can be applied for a single mode laser fabrication.
For additional selection of the non-uniformly spatially distributed optical modes in a triangular cavity, the parts of the triangular cavity with minimal mode intensity can be cut out. For example, for selective generation of the optical modes with n = 1, m = 5 (Fig. 9), the apexes of the triangle can be cut out (Fig. 10), thus forming a truncated triangular optical resonator (Fig. 2).
The advantage of a TDI semiconductor laser diode is that its optical cavity has a high quality factor of longitudinal optical modes, resulting from total internal reflection at all triangle facets as long as the refractive index of the semiconductor is greater than 2.0, and it can operate in a single mode or controllable multi-mode regimes which are needed for various applications such as CD and DVD pick up heads, high quality laser printers, communication and others.
The shape of the TDI semiconductor laser diode makes it technologically easy to assemble them into arrays and matrixes for threshold lowering and output power increasing. Optical connection between neighbouring TDI elements of an array or matrix can be controlled by the width, depth and shape of trenches separating the TDI array or matrix elements (Figs. 3-5).
The direction of light output from a TDI array or matrix semiconductor laser diode is determined by the shape of the edge element of the array or matrix (Figs. 3,4).
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It can be made of a specially designed triangle, different from those in the array, a waveguiding ridge, an optical fibre or other waveguiding structure.
Several arrays with different size of triangular cavities or different shapes of upper electrodes can be used for the production of multi-wavelength operation TDI semiconductor lasers diodes needed for communication purposes.
The triangular shape of the TDI semiconductor laser diode makes it technologically easy to make a two-dimensional triangular lattice on a wafer, which allows total utilization of the wafer for production of TDI semiconductor laser diode matrixes and arrays of various shapes.
TDI semiconductor laser diode hollow matrixes with various topologies, including hollow triangular, hollow hexagonal and others can be used for laser gyroscope applications (Fig.
5).
BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig. 1 exhibits the principal structure of a TDI semiconductor laser comprising a lower electrode 1, a substrate 2, a triangular mesa structure 3 and an upper multi-contact electrode 4; Fig. 2 exhibits the principal structure of a TDI semiconductor laser comprising a lower electrode 1, a substrate 2, a truncated triangular mesa-structure 3 and an upper multicontact electrode 4; Fig. 3 exhibits the principal structure of a semiconductor laser based on an array of TDI optical cavities comprising a lower electrode 1, a substrate 2 a triangular mesa structure elements 3, an upper multi-contact electrode 4, trenches 5 providing optical connection between neighbouring array elements and a light output element 6, the direction of output light being shown schematically by 7 ;
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Fig. 4 exhibits the principal structure of a semiconductor laser based on a matrix of TDI optical cavities comprising a lower electrode 1, a substrate 2, triangular mesa structure elements 3, an upper multi-contact electrode 4, trenches 5 providing optical connection between neighbouring array elements and a light output element 6, the direction of output light being shown schematically by 7; Fig. 5 exhibits the principal structure of a semiconductor laser gyroscope based on a hollow matrix of TDI optical cavities comprising a lower electrode 1, a substrate 2, triangular mesa structure elements 3, an upper multi-contact electrode 4, trenches 5 providing optical connection between neighbouring array elements, a hollow 8 and a light output element 6, the direction of the output light signal being shown schematically by 7; Fig. 6 schematically shows a two-dimensional semiconductor waveguiding layer comprising an upper mirror 9, a waveguiding layer 10 and a lower mirror 11, the light ray propagating along a path 12, forming an effective propagating angle ; Fig. 7 shows the intensity distribution of the lowest mode in a triangular optical cavity with quantum numbers n =1 and m =3,13 and 14 being X and Y coordinate axes respectively, 15 being the mode intensity axis, 16 being the border of the triangular optical cavity and 17 being an intensity maximum; Fig. 8 shows calculated shapes of upper TDI electrodes for the lowest mode in a triangular optical cavity with quantum numbers n =1 and m =3,13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 18, 19 and 20 being the shapes of TDI electrodes calculated at cut-off levels L, =0.1, Le =0. 5 and Le =0.9 respectively; Fig. 9 shows the intensity distribution of an optical mode with quantum numbers n =1 and m =5 in a triangular optical cavity, 13 and 14 being X and Y coordinate axes respectively, 15 being the mode intensity axis, 16 being the border of the triangular optical cavity and 17 being an intensity maximum, 21 being borders of areas near triangular apexes with low optical intensity, which can be cut off to form a truncated triangular optical cavity;
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Fig. 10 shows calculated shapes of upper TDI electrodes for a mode in a triangular optical cavity with quantum numbers n =1 and m =5,13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 18,19, 20 being the shapes of TDI electrodes calculated at cut-off levels Lc =0.1, Lc =0.5 and Lc =0.9 respectively, 21 being borders of areas near the triangular apexes with low optical intensity, which can be cut off to form a truncated triangular optical cavity; Fig. 11 shows shape of a triple upper TDI electrode at cut-off levels Lc =0. 5 for a mode in a triangular optical cavity with quantum numbers n =1 and m =5, 13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 19 being the shape of each TDI electrode; Fig. 12 shows the intensity distribution of an optical mode with quantum numbers n =1 and m =9 in a triangular optical cavity, 13 and 14 being X and Y coordinate axes respectively, 15 being the mode intensity axis, 16 being the border of the triangular optical cavity and 17 being an intensity maximum; Fig. 13 shows the calculated shapes of the upper TDI electrodes for a mode in a triangular optical cavity with quantum numbers n =1 and m =9,13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 18,19, 20 being the shapes of TDI electrodes calculated at cut-off levels Lc =0.1, Le =0. 5 and Lac =0. 9; Fig. 14 shows the shape of a multiple upper TDI electrode at cut-off levels L, =0. 5 for a mode in a triangular optical cavity with quantum numbers n =1 and m =9, 13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 19 being the shape of each TDI electrode; Fig. 15 shows the intensity distribution of an optical mode with quantum numbers n =1 and m =7 in a triangular optical cavity, 13 and 14 being X and Y coordinate axes respectively, 15 being the mode intensity axis, 16 being the border of the triangular optical cavity and 17 being an intensity maximum; Fig. 16 shows the calculated shapes of the upper TDI electrodes for a mode in a triangular optical cavity with quantum numbers n =1 and m =7,13 and 14 being X and Y coordinate
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axes respectively, 16 being the border of the triangular optical cavity and 18,19, 20 being the shapes of TDI electrodes calculated at cut-off levels Lc =0.1, Le =0.5 and Lc =0.9 ; Fig. 17 shows the shape of a multiple upper TDI electrode at cut-off levels Lc =0.5 for a mode in a triangular optical cavity with quantum numbers n =1 and m =7,13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 19 being the shape of each TDI electrode; Fig. 18 shows the intensity distribution of an optical mode with quantum numbers n =1 and m =11 in a triangular optical cavity, 13 and 14 being X and Y coordinate axes respectively, 15 being the mode intensity axis, 16 being the border of the triangular optical cavity and 17 being an intensity maximum; Fig. 19 shows the calculated shapes of the upper TDI electrodes for a mode in a triangular optical cavity with quantum numbers n =1 and m =11,13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 18, 19,20 being the shapes of TDI electrodes calculated at cut-off levels Le =0.1, Le =0.5 and Le =0. 9; Fig. 20 shows the shape of a multiple upper TDI electrode at cut-off levels Le =0.7 for a mode in a triangular optical cavity with quantum numbers n =1 and m =11, 13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 22 being the shape of each TDI electrode; Fig. 21 shows the shape of a multiple upper TDI electrode at cut-off levels Le =0.5 for a mode in a triangular optical cavity with quantum numbers n =1 and m =11, 13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 19 being the shape of each TDI electrode; Fig. 22 shows the intensity distribution of an optical mode with quantum numbers n =2 and m =14 in a triangular optical cavity, 13 and 14 being X and Y coordinate axes respectively, 15 being the mode intensity axis, 16 being the border of the triangular optical cavity and 17 being an intensity maximum;
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Fig. 23 shows the calculated shapes of the upper TDI electrodes for a mode in a triangular optical cavity with quantum numbers n =2 and m =14,13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 18,
19, 20 being the shapes of the TDI electrodes calculated at cut-off levels L, =0. 1, Le =0. 5 and Le =0. 9 ; Fig. 24 shows the shape of each multiple upper TDI electrode with a reduced number of contacts for a mode in a triangular optical cavity with quantum numbers n =2 and m =14, 13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 23 being the shape of each TDI electrode; Fig. 25 shows the intensity distribution of an optical mode with quantum numbers n =3 and m =21 in a triangular optical cavity, 13 and 14 being X and Y coordinate axes respectively, 15 being the mode intensity axis, 16 being the border of the triangular optical cavity and 17 being an intensity maximum; Fig. 26 shows the calculated shapes of the upper TDI electrodes for a mode in a triangular optical cavity with quantum numbers n =3 and m =21,13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 18,
19, 20 being the shapes of the TDI electrodes calculated at cut-off levels Le =0. 1, Le =0. 5 and L, =0. 9 ; Fig. 27 shows shapes of multiple upper TDI electrodes with a reduced number of contacts for a mode in a triangular optical cavity with quantum numbers n =3 and m =21,13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 23 being the shape of each TDI electrode; Fig. 28 shows the intensity distribution of an optical mode with quantum numbers n =1 and m =21 in a triangular optical cavity, 13 and 14 being X and Y coordinate axes respectively, 15 being the mode intensity axis, 16 being the border of the triangular optical cavity and 17 being an intensity maximum; Fig. 29 shows the calculated shapes of the upper TDI electrodes for a mode in a triangular optical cavity with quantum numbers 11 =3 and m =21,13 and 14 being X and Y
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coordinate axes respectively, 16 being the border of the triangular optical cavity and 18 and 19 being the shapes of TDI electrodes calculated at cut-off levels Le =0.1 and Le =0. 5; Fig. 30 shows the shapes of multiple upper TDI electrodes at cut-off levels Le =0. 5 for a mode in a triangular optical cavity with quantum numbers n =1 and m =21,13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 19 being the shape of each TDI electrode; Fig. 31 shows the shapes of multiple upper TDI electrodes with a reduced number of contacts for a mode in a triangular optical cavity with quantum numbers n =1 and m =21, 13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 24 being the shape of each TDI electrode; Fig. 32 shows the shape of a single upper TDI electrode with a reduced number of contacts for a mode in a triangular optical cavity with quantum numbers n = 1 and m =21, 13 and 14 being X and Y coordinate axes respectively, 16 being the border of the triangular optical cavity and 25 being the shape of the TDI electrode; Fig. 33 illustrates the principal scheme of a TDI semiconductor laser diode according to the following Examples 1,2 and 3; Fig. 34 illustrates the principal scheme of a TDI semiconductor laser diode according to the following Example 4; Fig. 35 illustrates the principal scheme of a TDI semiconductor laser diode according to the following Example 5; Fig. 36 illustrates the principal scheme of a TDI cascade semiconductor laser diode according to the following Example 6; Fig. 37 illustrates the principal scheme of a TDI array semiconductor laser diode according to the following Example 9;
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Fig. 38 illustrates the principal scheme of a TDI array semiconductor laser diode according to the following Example 10; and Fig. 39 illustrates the principal scheme of a TDI matrix semiconductor laser diode according to the following Example 13.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be more fully understood by reference to the following examples EXAMPLE 1 The principal scheme of a TDI semiconductor laser diode generating light with a wavelength in the range 700-1000 nm according to Example 1 is shown in Fig. 33.
It has a lower electrode 31 to a conductive n-GaAs substrate 32 with a surface plane orientation (111), a triangular or truncated triangular waveguiding mesa structure 33, consisting of a high-index AlGaAs two-dimensional waveguiding layer 34, a lower waveguiding mirror 35, made of a low-index n-type AlGaAs cladding layer or n-type A1GaAs.. superlattice, an upper waveguiding mirror 36, made of a low-index p-type AlGaAs cladding layer or p-type AlGaAs superlattice, an upper contact layer 37 made of p-type AlGaAs and an upper multi-contact TDI electrode 38, with contact spots shaped in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32.
The above shapes of the contact spots are achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of upper contact layer 37, or an ion-implantation treatment of the upper contact layer 37.
The waveguiding layer 34 contains an active layer 39, made of an InGaAs/GaAlAs double heterostructure or an InGaAs/GaAlAs single quantum well or InGaAs/GaAlAs multiple quantum wells or a current asymmetric resonance tunnelling structure (see GB 2 352 326).
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EXAMPLE 2 The principal scheme of a TDI semiconductor laser diode generating light with a wavelength in the range of 1300 nm or 1550 nm according to Example 2 is shown in Fig.
33.
It has a lower electrode 31 to a conducting n-InP substrate 32 with a surface plane orientation (111), a triangular or truncated triangular waveguiding mesa structure 33, consisting of a high-index InGaAsP two-dimensional waveguiding layer 34, a lower waveguiding mirror 35, made of an n-type InP cladding layer or n-type InGaAsP/InGaAsP superlattice or n-type ALInGaAs/AUnGaAs superlattice, an upper waveguiding mirror 36, made of a p-type InP cladding layer or p-type InGaAsP superlattice, an upper contact layer 37 made of p-type InP and an upper multi-contact TDI electrode 38, with contact spots shaped in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32.
The above shapes of the contact spots are achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of upper contact layer 37, or an ion-implantation treatment of the upper contact layer 37.
The waveguiding layer 34 contains an active layer 39, made of an InGaAsP/InGaAsP double heterostructure or an InGaAsP/InGaAsP single quantum well or InGaAsP/InGaAsP multiple quantum wells or a current asymmetric resonance tunnelling structure (see GB 2 352 326).
EXAMPLE 3 The principal scheme of a TDI semiconductor laser diode generating light with a wavelength in the range of 1300 nm according to Example 3 is shown in Fig. 33.
It has a lower electrode 31 to a conducting n-GaAs substrate 32 with a surface plane orientation (111), a triangular or truncated triangular waveguiding mesa structure 33, consisting of a high-index AlGaAs two-dimensional waveguiding layer 34, a lower waveguiding mirror 35, made of a low-index n-type AlGaAs cladding layer or n-type AlGaAs superlattice, an upper waveguiding mirror 36, made of a low-index p-type
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AlGaAs cladding layer or p-type AlGaAs superlattice, an upper contact layer 37 made of p-type AlGaAs, and an upper multi-contact TDI electrode 38, with contact spots shaped in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32.
The above shapes of the contact spots are achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of upper contact layer 37, or an ion-implantation treatment of the upper contact layer 37.
The waveguiding layer 34 contains an active layer 39, made of a GaAsSb/GaAlAs double heterostructure, or an InGaAsN/GaAlAs double hetero-structure, or a GaAsSb/GaAlAs single quantum well, or an InGaAsN/GaAIAs single quantum well, or a GaAsSb/GaAlAs multiple quantum wells, or InGaAsN/GaA1As multiple quantum wells or a current asymmetric resonance tunnelling structure (see GB 2 352 326).
EXAMPLE 4 The principal scheme of a TDI semiconductor laser diode generating light with a wavelength in the range 400-700 nm embodied in Example 4 is shown in Fig. 34.
It has a lower electrode 41 to a conducting n-GaN layer 42, grown on a sapphire substrate 43 with a surface plane orientation (0001), with use ofaBAlGaInN buffer layer 51 (see GB 2 350 721), a triangular or truncated triangular waveguiding mesa structure 44, consisting of a high-index InGaN two-dimensional waveguiding layer 45, a lower waveguiding mirror 46, made of a low-index n-type AlGaN cladding layer or an n-type AlGaN superlattice, an upper waveguiding mirror 47, made of a low-index p-type AlGaN cladding layer or p-type AlGaN superlattice, an upper contact layer 48 made of p-type AlGaN and an upper multi-contact TDI electrode 49, with contact spots shaped in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32.
The above shapes of the contact spots are achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of upper contact layer 48, or an ion-implantation treatment of the upper contact layer 48.
The waveguiding layer 45 contains an active layer 50, made of an InGaN/InGaAIN
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double heterostructure, or an InGaN/InGaAIN single quantum well, or InGaN/InGaAIN multiple quantum wells or a current asymmetric resonance tunnelling structure (see GB 2 352 326).
EXAMPLE 5 The principal scheme of a TDI semiconductor laser diode generating light with a wavelength in the range 400-700 run according to Example 5 is shown in Fig. 35.
It has a lower electrode 61 to a conducting n-SiC substrate 62, a BAlGaInN buffer layer 63 (see GB 2 350 721) an n-GaN layer 64, a triangular or truncated triangular waveguiding mesa structure 65, consisting of a high-index InGaN two-dimensional waveguiding layer 66, a lower waveguiding mirror 67, made of a low-index n-type AlGaN cladding layer or n-type AlGaN superlattice, an upper waveguiding mirror 68, made of a low-index p-type AlGaN cladding layer or p-type AlGaN superlattice, an upper contact layer 69 made of p-type AlGaN, and an upper multi-contact TDI electrode 70, with contact spots shaped in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig.
20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32.
The above shapes of the contact spots are achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of upper contact layer 69, or an ion-implantation treatment of the upper contact layer 69.
The waveguiding layer 66 contains an active layer 71, made of an InGaN/InGaAIN double heterostructure, or an InGaN/InGaAIN single quantum well, or InGaN/InGaAlN multiple quantum wells or a current asymmetric resonance tunnelling structure (see GB 2 352 326).
EXAMPLE 6 The principal scheme of a TDI cascade semiconductor laser generating light with a wavelength in the range 5000-12000 nm according to Example 6 is shown in Fig. 36.
It has a lower electrode 81 to a conducting n-GaAs substrate 82 with a surface plane orientation (111), a triangular or truncated triangular waveguiding mesa structure 83, consisting of an active high-index two-dimensional waveguiding layer 84, made of an
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InGaAs quantum cascade superlattice, a lower waveguiding mirror 85, made of a lowindex n-type AlGaAs cladding layer or n-type AlGaAs superlattice, an upper
waveguiding mirror 86, made of a low-index p-type AlGaAs cladding layer or p-type AlGaAs superlattice, an upper contact layer 87 made of p-type AlGaAs, and an upper multi-contact TDI electrode 88, with contact spots shaped in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig.
31 or Fig. 32.
The above shapes of the contact spots are achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of upper contact layer 87, or an ion-implantation treatment of the upper contact layer 87.
EXAMPLE 7 The principal scheme of a semiconductor laser based on an array of TDI optical cavities generating light with wavelength in the range 700-1300 nm according to Example 7 is shown in Fig. 3.
It consists of a lower electrode 1 to a conducting n-GaAs substrate 2 with a surface plane orientation (111), an array of triangular or truncated triangular waveguiding mesa structure elements 3 according to Example 1 or Example 3, an upper multi-contact electrode 4, trenches 5 providing optical connection between neighbouring array elements, and a light output element 6, the direction of output light being shown schematically by 7.
EXAMPLE 8 The principal scheme a semiconductor laser based on an array of TDI optical cavities generating light with wavelength in the range 1300 nm or 1550 according to Example 8 is shown in Fig. 3.
It consists of a lower electrode 1 to a conducting n-InP substrate 2 with a surface plane orientation (111), an array of triangular or truncated triangular waveguiding mesa structure elements 3 according to Example 2, an upper multi-contact electrode 4, trenches
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5 providing optical connection between neighbouring array elements, and a light output element 6, the direction of output light being shown schematically by 7.
EXAMPLE 9 The principal scheme of a semiconductor laser based on an array of TDI optical cavities generating light with a wavelength in the range 400-700 nm according to Example 9 is shown in Fig. 37.
It consists of a lower electrode 91 to a conductive n-GaN layer 92, grown on a sapphire substrate 93 with a surface plane orientation (0001), with use of BAlGaInN buffer layer (see GB 2 350 721), an array of triangular or truncated triangular waveguiding mesa structures 94 according to Example 4, an upper multi-contact electrode 95, trenches 96 providing optical connection between neighbouring array elements, and a light output element 97, the direction of output light being shown schematically by 98.
EXAMPLE 10 The principal scheme of a semiconductor laser. based on an array of TDI optical cavities generating light with a wavelength in the range 400-700 nm according to Example 10 is shown in Fig. 38.
It consists of a lower electrode 101 to a conducting n-SiC substrate 102, a BAIGaInN buffer layer 109 (see GB 2 350 721) an n-GaN layer 103, an array of triangular or truncated triangular waveguiding mesa structures 104 according to Example 5, an upper multi-contact electrode 105, trenches 106 providing optical connection between neighbouring array elements, and a light output element 107, the direction of output light being shown schematically by 108.
EXAMPLE 11 The principal scheme of a semiconductor laser based on a matrix of TDI optical cavities generating light with wavelength in the range 700-1300 nm according to Example 11 is shown in Fig. 4.
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It consists of a lower electrode 1 to a conducting n-GaAs substrate 2 with a surface plane orientation (111), a matrix of triangular or truncated triangular waveguiding mesa structure elements 3 according to Example 1 or Example 3, an upper multi-contact electrode 4, trenches 5 providing optical connection between neighbouring matrix elements and a light output element 6, the direction of output light being shown schematically by 7.
EXAMPLE 12 The principal scheme of a semiconductor laser based on a matrix of TDI optical cavities generating light with wavelength in the range 1300 nm or 1550 according to Example 12 is shown in Fig. 4.
It consists of a lower electrode 1 to a conducting n-InP substrate 2 with a surface plane orientation (111), a matrix of triangular or truncated triangular waveguiding mesa structure elements 3 according to Example 2, an upper multi-contact electrode 4, trenches 5 providing optical connection between neighbouring matrix elements, and a light output element 6, the direction of output light being shown schematically by 7.
EXAMPLE 13 The principal scheme of a semiconductor laser based on a matrix of TDI optical cavities generating light with a wavelength in the range 400-700 nm according to Example 13 is shown in Fig. 39.
It consists of a lower electrode 111 to a conducting n-SiC substrate 118, a BAIGaInN buffer layer 119 (see GB 2 350 721) an n-GaN layer 112, a matrix of triangular or truncated triangular waveguiding mesa structure elements 113 according to Example 4, an upper multi-contact electrode 114, trenches 115 providing optical connection between neighbouring matrix elements and a light output element 116, the direction of output light is shown schematically by 117.
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EXAMPLE 14 The principal scheme of a semiconductor laser gyroscope based on a hollow matrix of TDI optical cavities generating light with a wavelength in the range 700-1300 nm according to Example 13 is shown in Fig. 5.
It consists of a lower electrode 1 to a conducting n-GaAs substrate 2 with a surface plane orientation (111), a hollow matrix of triangular or truncated triangular waveguiding mesa structure elements 3 according to Example 1 or Example 3, an upper multi-contact electrode 4, trenches 5 providing optical connection between neighbouring matrix elements, a hollow 8 and a light output element 6, the direction of output light being shown schematically by 8.

Claims (23)

  1. CLAIMS 1. A semiconductor laser diode with spatially distributed current injection comprising : an active layer made of a III- V or II-VI semiconductor double heterostructure, single quantum well or multiple quantum wells or current asymmetric resonance tunnelling structure; an optical cavity made of a lateral waveguide comprising a Ill-V or II-VI semiconductor heterostructure or double heterostructure or index-graded structure or superlattice structure or another waveguide structure for vertical light confinement and a mesa structure for lateral light confinement; and a spatially distributed current injection system comprising a lower uniform singlecontact electrode and an upper multi-contact electrode with contact spots coinciding with maxima of intensity in a lateral plane for an optical mode of the optical cavity formed by the mesa structure.
  2. 2. A laser diode having a triangular or truncated triangular optical cavity with spatially distributed current injection (a TDI semiconductor laser) comprising: an active layer made of a IU- V or II-VI semiconductor double heterostructure, single quantum well or multiple quantum wells or a current asymmetric resonance tunnelling structure; an optical cavity made of a lateral waveguide comprising a III-V or II-VI semiconductor heterostructure or double heterostructure or index-graded structure or superlattice structure or another waveguide structure for vertical light confinement and a triangular or truncated triangular mesa structure for lateral light confinement; and a spatially distributed current injection system comprising a lower uniform singlecontact electrode and an upper multi-contact electrode with contact spots ordered in a two-dimensional triangular lattice, the nodes of the triangular lattice coinciding with
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    maxima of intensity for optical modes of the triangular cavity chosen for selective pumping.
  3. 3. An unipolar semiconductor laser having a triangular or truncated triangular optical cavity with spatially distributed current injection comprising: an active layer made of a III-V or II-VI semiconductor superlattice structure; an optical cavity made of a lateral waveguide comprising a III-V or II-VI semiconductor heterostructure or double heterostructure or index-graded structure or superlattice structure or another waveguide structure for vertical light confinement and a triangular or truncated triangular mesa structure for lateral light confinement; and a spatially distributed current injection system comprising a lower uniform singlecontact electrode and an upper multi-contact electrode with contact spots ordered in a two-dimensional triangular lattice, the nodes of the triangular lattice coinciding with maxima of intensity for optical modes of the triangular cavity chosen for selective pumping.
  4. 4. A resonance cavity light emitting diode having a triangular or truncated triangular optical cavity with spatially distributed current injection comprising: an active layer made of a III-V or II-VI semiconductor double heterostructure, single quantum well, multiple quantum wells or current asymmetric resonance tunnelling structure; an optical cavity made of a lateral waveguide comprising a III-V or II-VI semiconductor heterostructure or double heterostructure or index-graded structure or superlattice structure or another waveguide structure for vertical light confinement and a triangular or truncated triangular mesa structure for lateral light confinement; and a spatially distributed current injection system comprising a lower uniform singlecontact electrode and an upper multi-contact electrode with contact spots ordered in a two-dimensional triangular lattice, the nodes of the triangular lattice coinciding with
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    maxima of intensity for optical modes of the triangular cavity chosen for selective pumping.
  5. 5. An unipolar light emitting diode having a triangular or truncated triangular optical cavity with spatially distributed current injection comprising: an active layer made of a III- V or II-VI semiconductor superlattice; an optical cavity made of a lateral waveguide comprising a III-V or II-VI semiconductor heterostructure or double heterostructure or index-graded structure or superlattice structure or another waveguide structure for vertical light confinement and a triangular or truncated triangular mesa structure for lateral light confinement; and a spatially distributed current injection system comprising a lower uniform singlecontact electrode and upper multi-contact electrode with contact spots ordered in a twodimensional triangle lattice, the nodes of the triangular lattice coinciding with maxima of intensity for optical modes of the triangular cavity chosen for selective pumping.
  6. 6. A semiconductor laser diode based on an array of triangular or truncated triangular optical cavities with a spatially distributed current injection system.
  7. 7. An optical connection between neighbouring triangular optical cavities controlled by the width, depth and shape of separating trenches.
  8. 8. A light output element made of a triangular mesa structure, a ridge mesa structure, a planar waveguide mesa structure or a fibre attached to a side of any element of an array of triangular optical cavities.
  9. 9. A semiconductor laser diode based on a matrix of triangular or truncated triangular optical cavities with a spatially distributed current injection system.
  10. 10. A semiconductor laser diode for a laser gyroscope based on a hollow matrix of triangular or truncated triangular optical cavities with a spatially distributed current injection system.
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  11. 11. A TDI semiconductor laser diode generating light with a wavelength in the range 700-1000 nm substantially according to Example 1 comprising: a lower electrode to a conducting n-GaAs substrate with a surface plane orientation (111) ; a triangular or truncated triangular waveguiding mesa structure, comprising a high-index AlGaAs two-dimensional waveguiding layer; a lower waveguiding mirror, made of a low-index n-type AlGaAs cladding layer or an n-type AlGaAs superlattice; an upper waveguiding mirror, made of a low-index p-type AlGaAs cladding layer or a p-type AlGaAs superlattice; an upper contact layer made of p-type AlGaAs ; an upper multi-contact TDI electrode, with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of upper contact layer, or an ion-implantation treatment of the upper contact layer; and an active layer, made of an InGaAs/GaAlAs double hetero-structure or an InGaAs/GaAlAs single quantum well or InGaAs/GaAlAs multiple quantum wells or a current asymmetric resonance tunnelling structure.
  12. 12. A TDI semiconductor laser diode generating light with a wavelength in the range 1300 nm or 1550 nm substantially according to Example 2 comprising: a lower electrode to a conducting n-InP substrate with a surface plane orientation (111);
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    a triangular or truncated triangular waveguiding mesa structure, comprising a high-index InGaAsP two-dimensional waveguiding layer; a lower waveguiding mirror, made of an n-type InP cladding layer or n-type InGaAsP/InGaAsP superlattice or n-type ALInGaAs/AlInGaAs superlattice; an upper waveguiding mirror, made of a p-type InP cladding layer or p-type InGaAsP superlattice; an upper contact layer made of p-type LP ; an upper multi-contact TDI electrode, with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of the upper contact layer, or an ion-implantation treatment of the upper contact layer; and an active layer, made of an InGaAsP/InGaAsP double hetero-structure or an InGaAsP/InGaAsP single quantum well or InGaAsP/InGaAsP multiple quantum wells or a current asymmetric resonance tunnelling structure.
  13. 13. A TDI semiconductor laser diode generating light with a wavelength in the range 1300 nm substantially according to Example 3 comprising: a lower electrode to a conducting n-GaAs substrate with a surface plane orientation (111) ; a triangular or truncated triangular waveguiding mesa structure, comprising a high-index AlGaAs two-dimensional waveguiding layer; a lower waveguiding mirror, made of a low-index n-type AlGaAs cladding layer or n-type AlGaAs superlattice;
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    an upper waveguiding mirror, made of a low-index p-type AlGaAs cladding layer or p-type AlGaAs superlattice; an upper contact layer made of p-type AlGaAs ; an upper multi-contact TDI electrode, with contact spots shaped substantially in
    accordance with the Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of the upper contact layer, or an ion-implantation treatment of the upper contact layer; and an active layer made of a GaAsSb/GaAlAs double hetero-structure, or an InGaAsN/GaAIAs double hetero-structure, or a GaAsSb/GaAlAs single quantum well, or
    an InGaAsN/GaAIAs single quantum well, or GaAsSb/GaAlAs multiple quantum wells, or InGaAsN/GaAIAs multiple quantum wells or a current asymmetric resonance tunnelling structure.
  14. 14. A TDI semiconductor laser diode generating light with a wavelength in the range 400-700 nm substantially according to Example 4 comprising: a lower electrode to a conducting n-GaN layer, grown on a sapphire substrate with a surface plane orientation (0001), with the use ofaBAIGaInN buffer layer; a triangular or truncated triangular waveguiding mesa structure, comprising a high-index InGaN two-dimensional waveguiding layer; a lower waveguiding mirror, made of a low-index n-type AlGaN cladding layer or an n-type AlGaN superlattice; an upper waveguiding mirror, made of a low-index p-type AlGaN cladding layer or p-type AlGaN superlattice ; an upper contact layer made of p-type AlGaN ;
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    an upper multi-contact TDI electrode, with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-unifonn metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of the upper contact layer, or an ion-implantation treatment of the upper contact layer; and an active layer, made of an InGaN/InGaAIN double hetero-structure, or an InGaNIInGaA1N single quantum well, or InGaNlInGaA1N multiple quantum wells or a current asymmetric resonance tunnelling structure.
  15. 15. A TDI semiconductor laser diode generating light with a wavelength in the range 400-700 nm substantially according to Example 5 comprising: a lower electrode to a conducting n-SiC substrate; a BA1GaInN buffer layer; an n-GaN layer; a triangular or truncated triangular waveguiding mesa structure, comprising a high-index InGaN two-dimensional waveguiding layer; a lower waveguiding mirror, made of a low-index n-type AlGaN cladding layer or an n-type AlGaN superlattice; an upper waveguiding mirror, made of a low-index p-type AlGaN cladding layer or a p-type AlGaN superlattice; an upper contact layer made ofp-type A1GaN ; an upper multi-contact TDI electrode with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or
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    Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of the upper contact layer, or an ion-implantation treatment of the upper contact layer; and an active layer made of an InGaN/InGaAIN double hetero-structure, or an InGaN/InGaAIN single quantum well, or InGaN/InGaAIN multiple quantum wells or current asymmetric resonance tunnelling structure.
  16. 16. A TDI cascade semiconductor laser generating light with a wavelength in the range 5000-12000 nm substantially according to Example 6 comprising: a lower electrode to a conducting n-GaAs substrate with a surface plane orientation (111) ; a triangular or truncated triangular waveguiding mesa structure ; an active high-index two-dimensional waveguiding layer, made of an InGaAs quantum cascade superlattice; a lower waveguiding mirror, made of a low-index n-type AlGaAs cladding layer or an n-type AlGaAs superlattice; an upper waveguiding mirror made of a low-index p-type AlGaAs cladding layer or p-type AlGaAs superlattice; an upper contact layer made of p-type AlGaAs ; and an upper multi-contact TDI electrode with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of upper contact layer, or an ion-implantation treatment of the upper contact layer.
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  17. 17. A semiconductor laser based on an array of TDI optical cavities generating light with a wavelength in the range 700-1300 run substantially according to Example 7 comprising : a lower electrode to a conducting n-GaAs substrate with a surface plane orientation (111); an array of triangular or truncated triangular waveguiding mesa structure elements substantially according to Example 1 or Example 3; an upper multi-contact electrode with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of upper contact layer, or an ion-implantation treatment of the upper contact layer; trenches providing optical connection between neighbouring array elements; and a light output element made of a triangular mesa structure, a ridge mesa structure, a planar waveguide mesa structure or a fibre attached to a side of any element of the array of triangular optical cavities.
  18. 18. A semiconductor laser based on an array of TDI optical cavities generating light with a wavelength in the range 1300 nm or 1550 substantially according to Example 8 comprising : a lower electrode to a conducting n-InP substrate with a surface plane orientation (111) ; an array of triangular or truncated triangular waveguiding mesa structure elements substantially according to Example 2;
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    an upper multi-contact electrode with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of upper contact layer, or an ion-implantation treatment of the upper contact layer; trenches providing optical connection between neighbouring array elements; and a light output element made of a triangular mesa structure, a ridge mesa structure, a planar waveguide mesa structure or a fibre attached to a side of any element of the array of triangular optical cavities.
  19. 19. A semiconductor laser based on an array of TDI optical cavities generating light with a wavelength in the range 400-700 nm substantially according to Example 9 comprising : a lower electrode to a conducting n-GaN layer grown on a sapphire substrate with a surface plane orientation (0001) with the use ofa BAIGaInN buffer layer; an array of triangular or truncated triangular waveguiding mesa structures substantially according to Example 4; an upper multi-contact electrode with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of upper contact layer, or an ion-implantation treatment of the upper contact layer; trenches providing optical connection between neighbouring array elements; and
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    a light output element made of a triangular mesa structure, a ridge mesa structure, a planar waveguide mesa structure or a fibre attached to a side of any element of the array of triangular optical cavities.
  20. 20. A semiconductor laser based on an array of TDI optical cavities generating light with a wavelength in the range 400-700 run substantially according to Example 10 comprising : a lower electrode to a conducting n-SiC substrate; a BAlGaInN buffer layer; an n-GaN layer; an array of triangular or truncated triangular waveguiding mesa structures substantially according to Example 5; an upper multi-contact electrode with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of the upper contact layer, or an ion-implantation treatment of the upper contact layer; trenches providing optical connection between neighbouring array elements; and a light output element made of a triangular mesa structure, a ridge mesa structure, a plane waveguide mesa structure or a fibre attached to a side of any element of the array of triangle optical cavities.
  21. 21. A matrix of TDI optical cavities generating light with a wavelength in the range 700-1300 nm substantially according to Example 11 comprising:
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    a lower electrode to a conducting n-GaAs substrate with a surface plane orientation (111); a matrix of triangular or truncated triangular waveguiding mesa structure elements substantially according to Example 1 or Example 3; an upper multi-contact electrode with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of the upper contact layer, or an ion-implantation treatment of the upper contact layer; trenches providing optical connection between neighbouring matrix elements; and a light output element made of a triangular mesa structure, a ridge mesa structure, a planar waveguide mesa structure or a fibre attached to a side of any element of the matrix of triangular optical cavities.
    22. A semiconductor laser based on a matrix of TDI optical cavities generating light with a wavelength in the range 1300 nm or 1550 substantially according to Example 12 comprising : a lower electrode to a conducting n-InP substrate with a surface plane orientation (111) ; a matrix of triangular or truncated triangular waveguiding mesa structure elements substantially according to Example 2; an upper multi-contact electrode with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask
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    with windows, or a non-uniform doping of upper contact layer, or an ion-implantation treatment of the upper contact layer; trenches providing optical connection between neighbouring matrix elements; and a light output element made of a triangular mesa structure, a ridge mesa structure, a planar waveguide mesa structure or a fibre attached to a side of any element of the matrix of triangular optical cavities.
  22. 22. A semiconductor laser based on a matrix of TDI optical cavities generating light with a wavelength in the range 400-700 nm substantially according to Example 13 comprising : a lower electrode to a conducting n-SiC substrate; a BAIGalnN buffer layer; an n-GaN layer; a matrix of triangular or truncated triangular waveguiding mesa structure elements substantially according to Example 4; an upper multi-contact electrode with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of the upper contact layer, or an ion-implantation treatment of the upper contact layer; trenches providing optical connection between neighbouring matrix elements; and a light output element made of a triangular mesa-structure different from those in the matrix.
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  23. 23. A semiconductor laser gyroscope based on a hollow matrix of TDI optical cavities generating light with a wavelength in the range 700 - 1300 run substantially according to Example 13 comprising: a lower electrode to a conducting n-GaAs substrate with a surface plane orientation (111); a hollow matrix of triangular or truncated triangular waveguiding mesa structure elements substantially according to Example 1 or Example 3; an upper multi-contact electrode with contact spots shaped substantially in accordance with Fig. 8 or Fig. 11 or Fig. 14 or Fig. 17 or Fig. 20 or Fig. 21 or Fig. 24 or Fig. 27 or Fig. 30 or Fig. 31 or Fig. 32, these shapes of contact spots having been achieved by a non-uniform metal deposition or a metal deposition over a dielectric mask with windows, or a non-uniform doping of the upper contact layer, or an ion-implantation treatment of the upper contact layer; trenches providing optical connection between neighbouring matrix elements; and a light output element made of a triangular mesa structure, a ridge mesa structure, a planar waveguide mesa structure or a fibre attached to a side of any element of the hollow matrix of triangular optical cavities.
GB0124715A 2001-10-15 2001-10-15 Semiconductor laser diodes Expired - Fee Related GB2384617B (en)

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