Semiconductor laser with a broad periodically segmented strip contact

 

(57) Abstract:

The invention relates to the field of laser technology, in particular to systems diode pumping, medical lasers, and laser systems used in computers, office equipment and entertainment industry. Semiconductor laser contains was highly reflective mirror, the active element, provided with a periodically segmented electrode, collimating lens and waveguide-grating mirror set at an angle to the axis of the active element. Was highly reflective mirror is made in the form of a multilayer dielectric coating deposited on the end face of the active element. Waveguide-grating mirror is made either in the form of a film waveguide deposited on a corrugated substrate, either in the form of a corrugated waveguide layer deposited on a flat substrate, or a dielectric layer with a periodic modulation of the refractive index deposited on a planar dielectric substrate. Various modifications of the semiconductor lasers contain the active element in the form of laser diode bars, or in the form of a set of laser diodes or laser diode, arranged one below the other, but so that the ends of the laser diodes is partially reflecting mirror, either partitioned waveguide-grating mirror, or both together. Effect: increase the brightness of the semiconductor laser with a wide active area and a reduction of the spectral width of the radiation line. 22 C.p. f-crystals, 6 ill.

The invention relates to the field of laser technology, in particular to systems diode pumping, medical lasers, and laser systems used in computers, office equipment and entertainment.

Known semiconductor laser with a wide active region containing optically connected and successively installed along the optical axis of the first output mirror, the active element and the second mirror with a cylindrical was highly reflective surface, installed so that forming a cylindrical surface perpendicular to the plane of the p-n junction of the active element, while the output mirror is made in the form of a dielectric coating on the output end of the active element [Century. Century. the Keeper, B. N. Konyaev, N. In.Markov, G., Kharisov "Narrowing the beam of a powerful injection lasers with a wide band of contact with external microelectro". Quantum electronics, 1994, T. 21, 1, c. 57].

Closest to the claimed is known semiconductor laser, with a wide active region containing optically connected and successively installed along the optical axis was highly reflective first mirror, an active element, a spherical lens and selectivity element made in the form of a cylindrical lens and a reflecting flat mirror, and forming a cylindrical surface of the lens is perpendicular to p-n-transition of the active element. In this laser the first mirror is made in the form of a multilayer dielectric coating on the input face of the active element, the aperture of the second end face of the active element optically aligned with the aperture selectivity of reflecting element using a spherical lens [M. C. Snipes, J. G. McInerney "Transverse mode filtering of wide stripe semiconductor lasers using an external cavity", SPIE, v. 1634, p. 532, 1992]. Using the selectivity of the element in this laser generates a strong dick is Azer by saving the main resonator mode.

The disadvantage of the closest analogue is the difficulty settings selectivity of the laser element, the length of the resonator (L=85 mm) and low power output of its (Ro=0,3 W in continuous mode). Semiconductor laser with a narrow radiation pattern works provided well-defined arrangement of the cylindrical lenses and flat mirrors constituting the selector mod, relative to each other and relative to the collimating spherical lens, the focus of which is placed the end of the active element. Even a small displacement of the elements of the selector relative to the optimal positions distorts the pattern and lowers the brightness of the laser output.

Using the present invention solves the technical problem of increasing the brightness of the semiconductor laser with a wide active area and reduce the spectral width of the radiation line.

The technical problem is solved by the fact that in the known semiconductor laser with a wide active region containing successively installed along the optical axis was highly reflective first mirror, an active element, collimating lens and optically associated salgo coating on the input face of the active element, and the second end is enlightened (R<0.5%) and is installed in the focus of the collimating lens, as the selector mod introduced a flat waveguide-grating mirror reflecting light (R50%) normal in a narrow spectral range (<20 nm), and the axis of the mirror, i.e., normal to its surface, is located in the plane of the p-n junction of the active element and mounted at an angle lying in the range from 1 to 6o(1o6o), to the axis of the active element, and a wide strip of contact on the surface of the active element closest to the active layer of the laser diode, periodically partitioned, and the period of partition kequalk= /2sin and orientation of the individual Poloskov contact coincides with the direction of the axis of the active element.

In particular, waveguide-grating mirror can be made in the form of one corrugated dielectric layer lying on the substrate, a refractive index of nswhich is less than the refractive index of nfdielectric layer, and the period of the corrugation is equal to: = /n*where n is the effective refractive index of the waveguide is determined from the dispersion relation:

< / BR>
where k = 2/, h is the thickness of the dielectric layer, the wavelength generated by the-n junction, and =2 if the strokes of the lattice perpendicular to the plane of the p-n junction.

In particular, waveguide-grating mirror can be made in the form of a single dielectric layer lying on a corrugated substrate with ns<nand = /n*.

In particular, waveguide-grating mirror can be made in the form of multilayer dielectric coatings, lying on a corrugated substrate.

In particular, waveguide-grating mirror can be made in the form of a dielectric layer on a flat substrate with ns<nand grill, = /n*formed within the dielectric layer by a periodic modulation of the refractive index of this dielectric layer.

In particular, waveguide-grating mirror can be made in the form of a lattice, autocollimation reflecting light, and the lattice must be installed so that the strokes it is oriented parallel to the plane of the p-n junction of the active element of the laser and the projection of the points of the lattice on the plane make with the axis of the active element angle (/2-).

In particular, waveguide-grating in a laser mirror, autocollimation reflect light, can be made in the form of metal-dielectric the fra which is equal to where the angle of incidence of light on the grid, and can also be made in the form of a multilayer dielectric mirror, lying on a flat substrate and on the surface of the dielectric mirrors deposited corrugated waveguide layer with the period of the corrugation, equal , where the angle is determined from the condition n*l= sin, where nl* is the effective refractive index of fashion leakage waveguide layer.

In particular, a semiconductor laser with waveguide-grating mirror may further comprise a saturable absorber located between was highly reflective mirror at the end of the active element and waveguide-grating mirror.

In particular, a semiconductor laser with waveguide-grating mirror set at an angle to the axis of the active element can optionally contain a second external mirror mounted at an angle to the axis of the active element, i.e. a mirror placed at an angle , but on the other side of the axis of the active element of the laser and the axis of the waveguide-grating mirrors and additional external mirrors are located in the plane of the p-n junction of the active element and the angle lies in the range 1o6o.

In particular, the semiconductor laser Inza and the external mirror. Moreover, the second external mirror may be spherical, and the laser may further comprise a spherical lens mounted so that its focus coincides with the center of curvature of the spherical mirror, wherein the nonlinear element is installed in the caustic formed by the telescopic system.

In particular, the nonlinear element can be made in the form of a nonlinear waveguide, the ends of the waveguide must be combined with tricks spherical lens and an additional spherical mirror.

In particular, the active element is a semiconductor laser with a waveguide-grating mirror can be made in the form of a laser diode array, optical agreed with this mirror by using a single cylindrical lens.

In particular, in the resonator of a semiconductor laser line diode lasers between the collimating lens and waveguide-grating mirror can be mounted perpendicular to the axis of the active element more partially reflecting flat mirror, and the distance L from the collimating lens to the mirror is equal

< / BR>
where W is the width of the active area of the individual diode laser, d is the distance between adjacent diode LAZ.

In particular, additional partially reflective flat mirror and waveguide-grating mirror in the laser can be fabricated on the same wedge-shaped substrate, and the angle of the wedge in the substrate is equal to /ne= , where neis the refractive index of the wedge-shaped substrate.

In particular, the semiconductor laser may include an active element in the form of a set of equidistant spaced one below the other laser diodes, optically coupled with one segmented waveguide-grating mirror, the ends of all of the laser diodes in parallel with each other, the period of partition waveguide-grating mirrors is equal to the distance between the planes of the p-n junctions of diode lasers, and the size of the individual mirrors in the section is equal to the corresponding this section, the individual size of the laser beam.

In particular, the active element of the semiconductor laser can be a set of equidistant arranged one below the other of the arrays of laser diodes, all of the laser diodes in a single line is optically associated with one section of the waveguide-grating mirrors through a collimating lens.

In particular, a semiconductor laser with a set of erpendicular axis of the active element between the collimating lens and periodically segmented waveguide-grating mirror at a distance from the collimating lens.

In particular, additional partially reflecting mirror and waveguide-grating mirror can be fabricated on the same substrate.

In particular, additional partially reflective mirror may be made in the form of a partitioned waveguide-grating mirrors installed between the collimating lens and waveguide-grating mirror in parallel waveguide-lattice mirror.

The essence of the invention consists in that in a semiconductor laser with an external mirror mounted at an angle to the axis of the laser, the feedback occurs in Brekhovskikh reflection of light by periodic variation of the refractive index (lattice n) generated in the active layer of the laser under periodically partitioned contact when the current flowing through the laser. Due to the partial reflection of light on Breggovskoi the grating period whichk= /2sin, laser radiation falls on was highly reflective mirror printed directly on the end face of the active element, an angle of /n and/n, under the same angles and it is reflected from this mirror. In the area of overlap of the incident and the reflected beam occurs an interference modulation of the intensity of the optical field, which is about volume. The period of this grating

and strokes her parallel to the plane of the mirror at the end of the active element. The periodic change in the refractive index of the active medium along the axis of the active region plays the role of an additional selector modes that produce a single longitudinal mode in the radiation of a semiconductor laser. The initial spectral selector radiation is waveguide-grating mirror, it is necessary to limit the range of periods that occur at the beginning of operation of the laser arrays. The same role is played Breggovskie lattice under partitioned contact (electrode) of the laser. Subsequent operation of the laser is accompanied by a selection (the survival of) the lattice only one period, providing maximum gain generated fashion. Periodic change of the refractive index inside the active medium provides a selection of longitudinal modes, the spatial coherence of laser radiation throughout the cross section of the active region, and the output radiation from the resonator of a semiconductor laser, which is at an angle to the axis of the active element. Since the period of the partition of contact (electrode) is equal to and touches this electrode grating is directed along the axis Lazee conditions mutually agreed emergence and growth of the above-mentioned selectivity grilles (c) refractive index.

In Fig.1 presents a diagram of the inventive semiconductor laser. Semiconductor laser contains the first was highly reflective mirror 1, the active element 2, provided partitioned contact (electrode) 3, an antireflection coating 4 on the output side of the active element, collimating cylindrical lens 5 is set so that the generatrix of the cylinder parallel to the plane of the p-n junction of a semiconductor laser diode, and the focal point of the lens coincides with the position of the second end face of the active element, and a waveguide-grating mirror 6, the normal of which lies in the plane of the p-n junction of the active element and mounted at an angle to the axis of the active element.

In Fig. 2 presents a diagram of a semiconductor laser with two external mirrors and additional elements that extend its functionality. In particular, between the collimating lens 5 and waveguide-grating mirror 6 introduced saturable absorber 7, the path of the output beam placed second external mirror 8, which reflects the output beam ago, and between this mirror and the collimating lens introduced nonlinear element 9, which in the case of spherical reflective Zeta 8 and 10.

In Fig. 3 provides a schematic diagram of a semiconductor laser with an additional partially reflective mirror 11, which is placed between the collimating lens 5 and waveguide-grating mirror 6. Partially reflecting mirror 6 is set normal to the axis of the active element and optically connects all diode lasers line between them.

In Fig. 4 shows a diagram of a semiconductor laser with an active element 2 in the form of a set of diode lasers, located equidistant one from another and optically coupled with partitioned mirror 6 through the collimating lens 5, the number of which is equal to the number of diode lasers in the set and the number of corrugated sections 12 in a partitioned waveguide-grating mirror 6. All diode lasers in the set is optically connected via a waveguide mirror 6.

In Fig. 5 shows a diagram of a semiconductor laser with an active element 2 in the form of a set of lines of diode lasers, segmented waveguide-grating mirror 6 and partially reflective mirror. All diode lasers in the active optical element 2 are connected via a partitioned waveguide-grating mirror 6 and partially reflective mirror 11.

the development, in the resonator which introduced an additional partially reflective waveguide-grating mirror 14. All diode lasers in the active optical element 2 are connected to each other via a partitioned waveguide-grating mirrors 6 and 14.

The inventive semiconductor laser operates in the following manner. Spontaneous emission of the active region of the laser falls on the waveguide-grating mirror 6 is reflected by this mirror back, going collimating lens 5 on the end face of the active element and enters the active region of the laser diode 2, where it is on the way to the mirror 1 is enhanced. After reflection of increased radiation on the mirror 1, it again passes the active medium is amplified and passed collimating lens 5, leaves the resonator of the laser. In this part of the radiation in Brekhovskikh reflection on the grating of the refractive index, formed by the injection of carriers under partitioned contact (electrode), returns to the resonator, thus providing feedback and contributing to the emergence and growth of lattice refractive index, formed in the overlapping region incident on the mirror 1 and the reflected light beams inside the active region 2. Arising raspredelenie the mirror 1. Distributed along the axis of the reflected light selectarum its wavelength, providing maximum gain for only one longitudinal fashion. Due to the fact that the light in the active medium 2 is distributed not only along the axis of the active region 2, but across it, the periodic change of the refractive index along the axis of the active element are synchronized in phase, defining a narrow, close to the diffraction limit beam of laser output.

When the active element 2 of a semiconductor laser is a line of diode lasers and the inside of the resonator placed his extra flat partially reflecting mirror 11, as shown in Fig. 3A, when establishing its reflecting surface in the plane of intersection of the collimated light beams from the adjacent laser diodes, i.e. at a distance

< / BR>
from the collimating lens between the individual laser diodes optical communication occurs in which part of the radiation from one diode falls into two adjacent (left and right) of the laser diode in the line. Such an optical communication leads to synchronization of the individual laser diodes in the line and to increase the spatial coherence of the total radiation needname lasers in the line. When the laser this connection is achieved using a partitioned waveguide-grating mirror 6. Lots of corrugated waveguide 12 are separated by flat sections 13 of the waveguide. When the laser on the sections 12 of the mirror 6 is excited waveguide fashion, which creates reflected back wave and partially enters the flat section of the waveguide 13 of the mirror 6. Waveguide fashion cover section 13 in the direction to the two adjacent corrugated sections 12, where it is emitted normal to the mirror 6 and into neighboring laser diodes through the collimating lens 5. Thus, when the laser is implemented optical communication between all laser diodes in the line 2. This link leads to a synchronization of the individual lasers in the line and to increase the spatial coherence of laser radiation.

In Fig. 4 shows a diagram of a semiconductor laser with an active element in the form of a set of 2 laser diodes. Laser diodes optically associated with the segmented waveguide-grating mirror 6 set collimating lens 5. Each collimated beam of light has its own separate section 12 of corrugated waveguide is partitioned external waveguide-grating mirror the sections of the light emitted from the waveguide is missing. When the laser shirred section 12 of the waveguide mirror 6 is excited waveguide fashion, which creates a reflective wave and partially enters the flat (not) part of the waveguide 13 on the mirror 6. Waveguide fashion cover section 13 in the direction to the two adjacent corrugated sections 12, where it is emitted normal to the mirror 6 and into neighboring laser diodes through the collimating lens 5. Thus, when the laser is implemented optical communication between all laser diodes in the set 2. This link leads to a synchronization of the individual laser diodes in the set 2 and to increase the spatial coherence of the total radiation output of a semiconductor laser.

In Fig. 5 shows a diagram of a semiconductor laser with an active element 2 in the form of a set of arrays of laser diodes arranged one under the other, optically coupled with segmented waveguide-grating mirror 6 set collimating lens 5. Inside the cavity between the lens 5 and the mirror 6 is placed partially reflecting mirror 11. The mirror 11 is set normal to the axis of the active element 2 at a distance from the collimating lens 5. The mirror 11 and the mirror 6 provide Opti is all laser diodes in the lines and set 2 as a whole and to increase the spatial coherence of the total radiation output of a semiconductor laser.

In Fig. 6 shows another variant of the optical connection between the diode lasers in the set 2 lines of diode lasers. When the laser this connection is achieved using partitioned mirrors 6 and 14. The mirror is partitioned in two mutually perpendicular directions. When light falls on the mirror 14 and the mirror 6, the portion of the light from one corrugated section of the mirror falls into another through a flat section of the waveguide and radiated normal to the mirror, getting into neighboring laser diodes. Thus, when the laser is implemented communication between all diode lasers in set of 2 and max TWAIN synchronizes their work, which increases the spatial coherence of the laser.

In microlaser made according to the invention, as the active element 2 is used, the laser diode InGaAs/InGaP/GaAs quantum well within the waveguide layer. The diodes had a length of 1=0.5 mm, the width of the active area W=360 μm and the period of the partition strip contactk= 10 μm. At one end of the diode was nubilalis ar coating (R0,5%), and on the other end of the reflective mirror 1 (R95%). The band maximum of the luminescence diode was localized near 997 nm. As a collimating lens 5 was used optical fiber diametre mirror 6 was a single-layer waveguide (film TA2ABOUT5nf= 2,02) on corrugated glass substrate (ns=1,512). This mirror has the following parameters: =643 nm, the depth of the corrugations 2=200 nm, the thickness of the layer of Ta2ABOUT5h= 220 nm, the reflectance of the mirror at the wavelength =997 nm was Rm= 98%, the width of the reflection line 10 nm. Waveguide-grating mirror was attached to the quote table, allowing rotation around the axis perpendicular to the plane of the p-n junction of the laser diode. The maximum brightness of the radiation angle of rotation of the mirror amounted to 3o. Under these conditions, was obtained at the output of a semiconductor laser 1.2W output power with angle of divergence in the plane of the p-n junction = 0,3and line width generationgene= 0.1 nm.

1. Semiconductor laser with a wide active region containing successively installed along the optical axis was highly reflective mirror, the active element, collimating lens and optically associated selector mod, working in reflection mode, and was highly reflective mirror of the resonator is made in the form of a multilayer dielectric coating on one end of the active element and the other end is enlightened and installed in focus calimero is no normal in the narrow spectral range of 20 nm), moreover, the axis of this mirror is located in the plane of the p-n junction of the active element and mounted at an angle lying in the range 1o6oto the axis of the active element, and the wide blade on the surface of the active element closest to the active layer of the diode laser, periodically partitioned, and the period of partitiontoequal

< / BR>
and the direction of the individual Poloskov partitioned contact coincides with the axis direction of the active area of the diode laser.

2. Semiconductor laser under item 1, characterized in that the waveguide-grating mirror is designed as one corrugated dielectric layer lying on a flat substrate, a refractive index of nSwhich is less than the refractive index of nfdielectric layer, and the period of the corrugation is equal to

= /n*where n* is the effective refractive index of the waveguide is determined from the dispersion relations

< / BR>
where

h - thickness of the dielectric layer;

the wavelength of the generated light;

m - number of fashion (positive integer);

value = 0 if the strokes of the lattice parallel to the plane of the p-n junction, and = 2 if the strokes of the lattice perpendicular to the plane of the p-n junction has acrylo made in the form of a single layer of dielectric, lying on a corrugated substrate with nS<nand = /n*.

4. Semiconductor laser under item 1, characterized in that the waveguide-grating mirror is made in the form of a multilayer dielectric coatings, lying on a corrugated substrate.

5. Semiconductor laser under item 1, characterized in that the waveguide-grating mirror is made in the form of a dielectric layer on a flat substrate with nS<nand grill, = /n*formed within the dielectric layer by a periodic modulation of the refractive index of this dielectric layer.

6. Semiconductor laser under item 1, characterized in that the waveguide-grating mirror is made in the form of a lattice autocollimation reflecting light, and the grating is set so that the strokes it is oriented parallel to the plane of the p-n junction of the active element and the projection of the points of the lattice on the plane make with the axis of the active element angle .

7. Semiconductor laser under item 6, characterized in that the waveguide-grating mirror is made in the form of metal-dielectric grating autocollimation reflecting the incident light.

8. Semiconductor laser mirrors, lying on a corrugated substrate, the period of the corrugation which is

< / BR>
where is the angle of incidence of light on the grating.

9. Semiconductor laser under item 6, characterized in that the waveguide-grating mirror is made in the form of a multilayer dielectric mirror, lying on a flat substrate and on the surface of the dielectric mirrors deposited corrugated waveguide layer.

10. Semiconductor laser under item 1, characterized in that it further comprises a saturable absorber located between was highly reflective mirror at the end of the active element and waveguide-grating mirror.

11. Semiconductor laser under item 1, characterized in that it further comprises an external mirror mounted at an angle to the axis of the active element, i.e. a mirror placed at an angle , but on the other side of the axis of the active element of the laser and the axis of the waveguide-grating mirrors and additional external mirrors lie in the plane of p-n junction of the active element.

12. Semiconductor laser according to p. 11, characterized in that it further comprises a spherical lens installed between the collimating lens and the external mirror and outer mirror will the new laser p. 12, characterized in that it further comprises a nonlinear element mounted in caustic telescopic system formed by a spherical lens and a concave mirror.

14. Semiconductor laser under item 13, wherein the nonlinear element of the laser is made in the form of a nonlinear waveguide, and the ends of the waveguide are in focus spherical lens and a concave second external mirrors.

15. Semiconductor laser under item 1, characterized in that the active element of the laser is made in the form of a laser diode array, optically aligned with waveguide-grating mirror with one cylindrical collimating lenses.

16. Semiconductor laser according to p. 15, characterized in that the resonator of the laser between the collimating lens and waveguide-grating mirror mounted perpendicular to the axis of the active element more partially reflecting flat mirror, and the distance L from the collimating lens to the mirror is

< / BR>
where W is the width of the active area of the diode laser;

d - the distance between adjacent diode lasers in the line;

f is the focal distance of the cylindrical lens;

D is the thickness of the lens and n is pokazatel arcala done partitioned, moreover, the direction of the partition coincides with the direction of the vector lattice of the mirror, and the period of partition coincides with the period of placement of the laser diodes in the line.

18. Semiconductor laser under item 1, characterized in that the active element of the laser is a set of equidistant spaced one below the other laser diodes, optically coupled with one segmented waveguide-grating mirror through individual collimating lenses, and the ends of the laser diodes in parallel with each other, the period of partition waveguide-grating mirrors is equal to the distance between the planes of the p-n junctions of diode lasers, and the size of the individual mirrors in the section is equal to the corresponding of this section to the size of the individual laser light beam.

19. Semiconductor laser under item 18, characterized in that the active element of the laser is a set of equidistant arranged one below the other of the arrays of laser diodes, all of the laser diodes in a single line is optically associated with one section of the waveguide-grating mirrors through a collimating lens.

20. Semiconductor laser under item 19, characterized in that Ino perpendicular to the axis of the active element more partially reflecting flat mirror, moreover, the position of this mirror is defined according to p. 16.

21. Semiconductor laser according to p. 20, characterized in that the additional partially reflective flat mirror and waveguide-grating mirror on one wedge-shaped substrate, and the angle of the wedge is equal to = /newhere neis the refractive index of the wedge-shaped substrate.

22. Semiconductor laser under item 19, characterized in that the resonator of the laser between the collimating lens and waveguide-grating mirror is installed parallel to this additional mirror partitioned waveguide-grating mirror that partially reflects the light along the normal, and the period of the partition of the mirror coincides with the period of placement of the laser diodes in the line, and the size of the corrugated section in the section of the mirror is equal to the width of the active area of the diode laser.

23. Semiconductor laser according to p. 22, characterized in that the additional partially reflective and waveguide-grating mirror is made on the same substrate.

 

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EFFECT: enhanced stability of directivity pattern of optical transmitting module due to reduced focal mismatch down to zero under impact of adverse mechanical and environmental factors.

1 cl, 3 dwg

FIELD: quantum electronics; semiconductor laser manufacture.

SUBSTANCE: applied to n-GaAs substrate in layer-by-layer manner are bottom n-Alz1Ga1 - z1As layer of shell, bottom light-guide n- or i-In0.49Ga0.51P layer, active Inx3Ga1 - y3Py3 layer with quantum well, top first light-guide i-In0.49Ga0.51P layer, sealing GaAs layer, and SiO2 layer. Then SiO2 film portion of about 20 μm in width is removed. When SiO2 film is used as mask, sealing layer disposed close to butt-end surface and first top light-guide layer are removed. After that SiO2 film, active layer with quantum well disposed close to butt-end surface, and remaining sealing layer are removed. Top p-Alz1Ga1 - z1As layer of shell and p-GaAs contact layer are deposited on second top p- or i-In0.49Ga0.51P layer. Laser radiation is generated in wavelength range of 0.7 - 1.2 μm.

EFFECT: enhanced operating reliability of laser unit at heavy output power.

19 cl, 10 dwg

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