Double-FP waveguide type laser integrated with surface grating

Abstract

The invention provides a double-FP waveguide type laser integrated with a surface grating. The double-FP waveguide type laser comprises an N-face metal electrode layer; an N-type substrate, a lower separation limiting layer, an active layer, an upper separation limiting layer and a double-FP-type ridge waveguide layer are sequentially stacked on the N-face metal electrode layer, and the double-FP-type ridge waveguide layer comprises two FP-type ridge waveguides which are arranged in parallel in the first direction; the ohmic contact layer is arranged on each FP type ridge waveguide; and the P-surface metal electrode layer is arranged on the ohmic contact layer. The laser is high in integration, external light feedback and external light injection are not needed, weak periodicity caused by light feedback is avoided, intra-cavity mode distribution is regulated and controlled by changing waveguide distribution and current injection conditions, multiple nonlinear states such as single-period, multi-period and four-wave mixing are achieved, and on-chip chaotic light signal output of a single longitudinal mode is generated.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor lasers, and in particular to a double FP waveguide laser with an integrated surface grating. Background Art

[0002] With the rapid development of the Internet, secure communication technology has become increasingly important. Chaotic optical communication, as a large-capacity communication technology that can achieve secure communication at the physical level, has attracted widespread attention. As the core component of chaotic optical communication systems, chaotic light sources are one of the research focuses in this field.

[0003] Traditional chaotic lasers are built with discrete components, which have high system complexity, large size and high production cost. In addition, traditional chaotic lasers that achieve chaotic states through optical feedback and other methods cannot avoid the weak periodicity caused by optical feedback. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the above-mentioned shortcomings, the main purpose of the present invention is to provide a dual FP waveguide laser with an integrated surface grating, which can regulate the intracavity mode distribution by changing the waveguide distribution and current injection conditions, realize multiple nonlinear states such as single cycle, multi-cycle, four-wave mixing, and generate a single longitudinal mode on-chip chaotic optical signal output.

[0006] (II) Technical solution

[0007] In order to achieve the above-mentioned object, the present invention provides a dual FP waveguide type laser with integrated surface grating, comprising: an N-side metal electrode layer; an N-type substrate, a lower separation restriction layer, an active layer, an upper separation restriction layer, and a dual FP type ridge waveguide layer are sequentially stacked on the N-side metal electrode layer, wherein the dual FP type ridge waveguide layer comprises two FP type ridge waveguides arranged in parallel along a first direction; an ohmic contact layer is arranged on each FP type ridge waveguide; and a P-side metal electrode layer is arranged on the ohmic contact layer.

[0008] In the above solution, the spacing between the two FP-type ridge waveguides along the first direction is related to the length of the FP-type ridge waveguide along the first direction, and the spacing is set in the range of 0.5-10 μm.

[0009] In the above scheme, the ohmic contact layer is separated by the etched groove, the etched groove divides the ohmic contact layer and the FP type ridge waveguide into a grating region and a gain region along the second direction, and the etched groove electrically isolates the grating region from the gain region.

[0010] The above scheme also includes a surface grating, which is a periodic groove structure arranged along the second direction in the grating area, and the surface grating is used to select the mode of the laser to generate a single longitudinal mode laser.

[0011] In the above scheme, the P-side metal electrode layer includes four P-side metal electrodes, which are respectively arranged on the ohmic contact layer of the grating region and the ohmic contact layer of the gain region to inject current into the grating region and the gain region of each FP-type ridge waveguide.

[0012] In the above scheme, the length range of the FP type ridge waveguide along the first direction is 1 to 5 μm, the length range of the FP type ridge waveguide along the second direction is 200-1200 μm, and the length range of the FP type ridge waveguide along the third direction is 1-3 μm, wherein the first direction, the second direction and the third direction are all perpendicular to each other.

[0013] In the above solution, the material structure of the active layer includes quantum wells, quantum dots and nanowire structures.

[0014] In the above scheme, the etching groove is filled with benzocyclobutene.

[0015] In the above scheme, the grating period d of the surface grating is p It follows from the following:

[0016] , where m is the order of the surface grating, is the Bragg wavelength, n eff is the effective refractive index of the FP-type ridge waveguide.

[0017] In the above scheme, the width of the etching groove is It follows from the following:

[0018] , where m s is the order of the etched grooves, is the Bragg wavelength, n s is the effective refractive index of the etched groove.

[0019] (III) Beneficial effects

[0020] The technical solution of the embodiment of the present invention has at least the following beneficial effects:

[0021] (1) The laser is not only highly integrated, but also does not require external optical feedback and external light injection, thus avoiding the weak periodicity caused by optical feedback.

[0022] (2) Realize the on-chip chaotic optical signal output of a single longitudinal mode through surface grating; control the transverse mode distribution in the cavity by adjusting the waveguide size and spacing; and control the actual output nonlinear state optical signal by injecting different currents. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A schematic diagram of the three-dimensional structure of a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention is shown;

[0024] Figure 2 A cross-sectional view schematically shows a double FP waveguide laser with integrated surface grating according to an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of mode field distribution of a fundamental transverse mode and a first-order transverse mode of a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention is schematically shown;

[0026] Figure 4 Schematically shows a side view of a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention;

[0027] Figure 5 The surface grating reflection spectrum of the dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention is schematically shown;

[0028] Figure 6 The schematic diagram shows a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention. GRATING1 = 20mA, I FP1 = 14mA, I GRATING2 = 20mA, I FP2 = Spectrum of periodic oscillation signal measured at 10mA;

[0029] Figure 7 The schematic diagram shows a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention. GRATING1 = 20mA, I FP1 = 14mA, I GRATING2 = 20mA, I FP2 = Spectrum of periodic oscillation signal measured when current is 10mA;

[0030] Figure 8 The schematic diagram shows a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention. GRATING1 = 20mA, I FP1 = 46mA, I GRATING2 = 20mA, I FP2 = Chaotic signal spectrum measured at 10mA;

[0031] Fig. 9 The schematic diagram shows a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention. GRATING1 = 20mA, I FP1 = 46mA, I GRATING2 = 20mA, IFP2 = 10mA chaotic signal spectrum measured. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0033] Figure 1 The three-dimensional structure of a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention is schematically shown. Figure 2 A cross-sectional view of a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention is schematically shown.

[0034] Please refer to Figure 1 and Figure 2 An embodiment of the present invention provides a dual FP waveguide laser with an integrated surface grating, comprising: an N-side metal electrode layer 1; an N-type substrate 2, a lower separation restriction layer 3, an active layer 4, an upper separation restriction layer 5, and a dual FP type ridge waveguide layer 6 are sequentially stacked on the N-side metal electrode layer 1, wherein the dual FP type ridge waveguide layer 6 includes two FP type ridge waveguides 61 arranged in parallel along a first direction X1; an ohmic contact layer 7 is arranged on each FP type ridge waveguide 61; and a P-side metal electrode layer 8 is arranged on the ohmic contact layer 7.

[0035] Specifically, the length of the FP type ridge waveguide 61 along the first direction X1 is in the range of 1 to 5 μm, the length of the FP type ridge waveguide 61 along the second direction X2 is in the range of 200-1200 μm, and the length of the FP type ridge waveguide 61 along the third direction X3 is in the range of 1-3 μm, wherein the first direction X1, the second direction X2 and the third direction X3 are perpendicular to each other. Figure 1 As shown, it can be understood that the first direction X1 is the short side width direction of the FP type ridge waveguide 61 , the second direction X2 is the long side direction of the FP type ridge waveguide 61 , and the third direction X3 is the height direction of the FP type ridge waveguide 61 .

[0036] In the embodiment of the present invention, both ends of the short side of the FP type ridge waveguide 61 are cleaved end faces or end face coating structures.

[0037] In an embodiment of the present invention, the material structure of the active layer 4 includes quantum well, quantum dot and nanowire structure.

[0038] In the embodiment of the present invention, the interval between two FP type ridge waveguides 61 along the first direction X1 is related to the length of the FP type ridge waveguide 61 along the first direction X1, and the interval setting range is 0.5-10 μm.

[0039] Specifically, the waveguide spacing between the two FP-type ridge waveguides 61 along the first direction X1 is related to the width of the FP-type ridge waveguide 61. For example, the waveguide spacing can be set to 0.5-10 μm according to the waveguide strip width, that is, the width of the FP-type ridge waveguide 61, so that the mode spacing of the transverse mode in the entire laser cavity can meet the requirements for the occurrence of nonlinear interaction.

[0040] Figure 3 A schematic diagram of mode field distribution of a fundamental transverse mode and a first-order transverse mode of a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention is schematically shown.

[0041] like Figure 3 As shown, the simulation method of finite element numerical calculation obtains that when the strip width of the two FP-type ridge waveguides 61 is 2μm, the waveguide height is 1.6μm, and the waveguide spacing is 2μm, the mode spacing ∆f between the fundamental transverse mode and the first-order transverse mode is about 16GHz, and the difference in mode spacing can be used to regulate the nonlinear interaction in the cavity.

[0042] Through the embodiments of the present invention, by changing the strip width and height of the FP-type ridge waveguide, the transverse mode distribution in the laser cavity can be adjusted to suppress unnecessary high-order transverse modes. By increasing the waveguide size, the output chaotic laser power can be increased. By adjusting the waveguide spacing, the coupling coefficient between the fundamental transverse mode and the first-order transverse mode in the cavity can be changed, thereby changing the frequency difference between the two groups of modes to achieve the required nonlinear interaction.

[0043] Figure 4 A side view of a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention is schematically shown.

[0044] Further, such as Figure 4 As shown, the ohmic contact layer 7 is separated by the etched groove 10, and the etched groove 10 divides the ohmic contact layer 7 and the FP type ridge waveguide 61 into a grating region and a gain region along the second direction X2, and the etched groove 10 realizes electrical isolation between the grating region and the gain region.

[0045] Exemplarily, benzocyclobutene may be filled in the etched groove 10 to prevent the metal electrode of the upper P-face metal electrode layer 8 from falling into the groove and causing light field loss.

[0046] Furthermore, the groove width d of the etched groove 10 is s It follows from the following:

[0047]

[0048] Among them, m s is the order of the etched groove 10, is the Bragg wavelength, n s is the effective refractive index of the etched groove 10.

[0049] Please continue reading Figure 4 In the grating area, a surface grating 9 is also included. The surface grating 9 is a periodic groove structure arranged along the second direction X2 in the grating area. The surface grating 9 is used to select the mode of the laser to generate a single longitudinal mode laser.

[0050] Furthermore, the grating period d of the surface grating 9 is p It follows from the following:

[0051]

[0052] Where m is the order of the surface grating 9, is the Bragg wavelength, n eff is the effective refractive index of the FP type ridge waveguide 61.

[0053] Figure 5 The surface grating reflection spectrum of a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention is schematically shown.

[0054] For example, Figure 5 As shown in FIG. 1 , the surface grating is designed for the band near the Bragg wavelength of 1550 nm. From the reflection spectrum, it can be predicted that the laser can achieve good single longitudinal mode output in this band.

[0055] like Figure 1 and Figure 4 As shown, the P-plane metal electrode layer 8 includes four P-plane metal electrodes, which are respectively arranged on the ohmic contact layer 7 of the grating region and the ohmic contact layer 7 of the gain region, so as to inject current into the grating region and the gain region of each FP-type ridge waveguide 61 .

[0056] For example, the P-surface metal electrode 81 and the P-surface metal electrode 82 are respectively disposed on the ohmic contact layer 7 of the gain region of the FP-type ridge waveguide 61 and the ohmic contact layer 7 of the grating region. The P-surface metal electrode 83 and the P-surface metal electrode 84 are respectively disposed on the ohmic contact layer 7 of the gain region of another FP-type ridge waveguide 61 and the ohmic contact layer 7 of the grating region. By controlling the magnitude of the injected current of the four P-surface metal electrodes and regulating the mode distribution in the entire cavity, nonlinear states such as single-cycle, multi-cycle, and four-wave mixing can be realized through the nonlinear interaction of different modes, and chaotic lasers can be generated.

[0057] For another example, the injected currents corresponding to the four P-side metal electrodes can be named I GRATING1 ,I FP1 ,I GRATING2 ,I FP2 .

[0058] It should be noted that if Figure 2As shown, the P-side metal electrode layer 8 can also be arranged on the double FP-type ridge waveguide layer 6 along the first direction X1 toward both sides of each FP-type ridge waveguide 61 .

[0059] Figure 6 The schematic diagram shows a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention. GRATING1 = 20mA, I FP1 = 14mA, I GRATING2 = 20mA, I FP2 = 10mA measured periodic oscillation signal spectrum. Figure 7 The schematic diagram shows a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention. GRATING1 =20mA, I FP1 = 14mA, I GRATING2 = 20mA, I FP2 = 10mA when the periodic oscillation signal spectrum is measured.

[0060] like Figure 6 and Figure 7 As shown, the laser is GRATING1 = 20mA, I FP1 = 14mA, I GRATING2 = 20mA, I FP2 =10mA, it can be seen from the spectrum and frequency spectrum of the periodic oscillation signal measured, that in this case of electrical injection, the intracavity mode beats, and a nonlinear state of periodic oscillation is obtained. From the spectrum, it can be seen that the laser achieves single longitudinal mode lasing well, schematically reflecting the role of the surface grating.

[0061] Figure 8 The schematic diagram shows a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention. GRATING1 = 20mA, I FP1 = 46mA, I GRATING2 = 20mA, I FP2 = 10mA chaotic signal spectrum measured. Fig. 9 The schematic diagram shows a dual FP waveguide laser with integrated surface grating according to an embodiment of the present invention. GRATING1 = 20mA, I FP1 = 46mA, I GRATING2 = 20mA, I FP2 = 10mA chaotic signal spectrum measured.

[0062] like Figure 8 and Fig. 9 As shown, the laser is GRATING1 = 20mA, IFP1 = 46mA, I GRATING2 = 20mA, I FP2 =10mA chaotic signal spectrum and spectrum diagram, the gray part in the spectrum diagram is the noise floor of the spectrum analyzer. It can be seen that under this electrical injection condition, the spectrum has been significantly broadened, and the spectrum has been significantly raised compared to the background noise signal. This result proves that the dual FP waveguide laser in this example produces chaotic optical signal output.

[0063] According to the embodiments of the present invention, by adjusting the injection currents corresponding to the four P-surface metal electrodes, the mode distribution in the cavity can be changed, multiple nonlinear interactions between different modes can be achieved, and chaotic lasers can be generated.

[0064] The dual FP waveguide laser with integrated surface grating based on the above-mentioned embodiment of the present invention is not only highly integrated, but also does not require external light feedback and external light injection, thereby avoiding weak periodicity caused by light feedback. Single longitudinal mode output is achieved through the surface grating, and the transverse mode distribution in the cavity is regulated by adjusting the waveguide size and spacing. The nonlinear state optical signal of the actual output is controlled by different injected currents.

[0065] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A dual FP waveguide laser with integrated surface grating, characterized in that: include: N-side metal electrode layer (1); An N-type substrate (2), a lower separation restriction layer (3), an active layer (4), an upper separation restriction layer (5), and a double FP-type ridge waveguide layer (6) are sequentially stacked on the N-side metal electrode layer (1), wherein the double FP-type ridge waveguide layer (6) comprises two FP-type ridge waveguides (61) arranged in parallel along a first direction; An ohmic contact layer (7) is arranged on each of the FP-type ridge waveguides (61); A P-side metal electrode layer (8) is arranged on the ohmic contact layer (7).

2. The dual FP waveguide laser with integrated surface grating according to claim 1, characterized in that: The spacing between the two FP type ridge waveguides (61) along the first direction is related to the length of the FP type ridge waveguide (61) along the first direction, and the spacing is set in a range of 0.5-10 μm.

3. The dual FP waveguide laser with integrated surface grating according to claim 1, characterized in that: The ohmic contact layer (7) is separated by an etched groove (10), and the etched groove (10) divides the ohmic contact layer (7) and the FP type ridge waveguide (61) into a grating region and a gain region along the second direction; and The etched groove (10) realizes electrical isolation between the grating region and the gain region.

4. The dual FP waveguide laser with integrated surface grating according to claim 1 or 3, characterized in that: It also comprises a surface grating (9), wherein the surface grating (9) is a periodic groove structure arranged along the second direction in the grating area, and The surface grating (9) is used to select the mode of the laser to generate single longitudinal mode laser.

5. The dual FP waveguide laser with integrated surface grating according to claim 1 or 3, characterized in that: The P-surface metal electrode layer (8) comprises four P-surface metal electrodes, which are respectively arranged on the ohmic contact layer (7) of the grating region and the ohmic contact layer (7) of the gain region, so as to inject current into the grating region and the gain region of each FP-type ridge waveguide (61).

6. The dual FP waveguide laser with integrated surface grating according to claim 1, characterized in that: The length of the FP type ridge waveguide (61) along the first direction ranges from 1 to 5 μm, the length of the FP type ridge waveguide (61) along the second direction ranges from 200 to 1200 μm, and the length of the FP type ridge waveguide (61) along the third direction ranges from 1 to 3 μm, wherein the first direction, the second direction and the third direction are all perpendicular to each other.

7. The dual FP waveguide laser with integrated surface grating according to claim 1, characterized in that: The material structure of the active layer (4) includes quantum wells, quantum dots and nanowire structures.

8. The dual FP waveguide laser with integrated surface grating according to claim 3, characterized in that: The etching groove (10) is filled with benzocyclobutene.

9. The dual FP waveguide laser with integrated surface grating according to claim 4, characterized in that: The grating period d of the surface grating (9) p It follows from the following: Wherein, m is the order of the surface grating (9), is the Bragg wavelength, n eff is the effective refractive index of the FP type ridge waveguide (61).

10. The dual FP waveguide laser with integrated surface grating according to claim 3, characterized in that: The groove width d of the etching groove (10) is s It follows from the following: Among them, m s is the order of the etching groove (10), is the Bragg wavelength, n s is the effective refractive index of the etched groove (10).

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