Metal limiting F-P cavity laser for on-chip integration

Abstract

The invention discloses a metal confinement F-P cavity laser for on-chip integration, which comprises an active semiconductor F-P cavity, optical dielectric layers, metal confinement layers, electrodes, a waveguide structure and a bonding layer, the optical dielectric layers are located at the two ends of the semiconductor F-P cavity, the metal confinement layers are located at the top of the F-P cavity and on the optical dielectric layers at the two ends of the F-P cavity, and the electrodes are located on the waveguide structure. The electrode is connected with the electric injection layer of the F-P cavity, and the F-P cavity and the waveguide structure are bonded through a transparent bonding layer. By changing structural parameters and adjusting coupling between an F-P cavity resonance mode and a waveguide guide mode, single-end coupling output exceeding 55% and double-end coupling output exceeding 80% are achieved respectively; the Q value of the F-P cavity laser is greatly improved through the metal limiting layer, the size of the laser can be reduced to be within 10 micrometers, miniaturization of the F-P cavity is achieved, and the F-P cavity has important application prospects in the fields of on-chip optical interconnection, on-chip integration and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of on-chip integrated laser light sources, and in particular to a metal-confined FP cavity laser for on-chip integration. Background Art

[0002] Semiconductor lasers are the smallest and most energy-efficient lasers of all types of lasers, and have great application prospects in the fields of photonic integrated chips, on-chip optical interconnection, optical communications, medical treatment, biosensors, etc. Since the first generation of semiconductors, GaAs homojunction injection semiconductor lasers, successfully developed by American scientists in 1962, which shrunk the laser from meters to millimeters for the first time, vertical cavity surface emitting lasers (VCSELs), micro-columns, micro-disks, micro-sphere lasers based on whispering gallery modes, photonic crystal lasers, and semiconductor nanowire or nanorod lasers have gradually reduced the size of semiconductor lasers by five orders of magnitude. However, these micro-lasers still have many limitations in practical applications. For example, although the modes of micro-disk and micro-column lasers are mainly confined to the active region, they will exceed the physical boundaries of the resonant cavity and produce mode coupling with adjacent devices, making it difficult to achieve dense integration. Although the mode volume of photonic crystal lasers is small, the existence of the Bragg period makes the entire structure size of the laser still quite large, and the preparation process of photonic crystal lasers, especially electrically excited photonic crystal lasers, is relatively complex. The coupling of micro-disk, photonic crystal and other lasers with optical waveguides is relatively difficult, and achieving higher coupling efficiency places strict requirements on the alignment accuracy between the laser and the waveguide.

[0003] In 2007, Hill et al. used metal-coated semiconductor lasers to achieve lasing under low-temperature electrical pumping and reduced the size of the laser to subwavelength. The introduction of metal coatings can not only act as a reflector to confine light to a volume much smaller than the wavelength of the light wave, suppress optical mode leakage and effectively isolate it from surrounding adjacent devices, but also act as a metal contact angle under electrical pumping to achieve current injection, bringing new opportunities for miniaturization of lasers to adapt to the development of high integration.

[0004] As a type of semiconductor laser, FP cavity laser uses FP cavity as resonant cavity. It has the characteristics of simple structure, tunable wavelength, wide wavelength range, etc. Its resonant mode is similar to the waveguide mode, and it is easy to couple with the waveguide to achieve efficient coupled output of energy, which makes it have broad application prospects in optical communication, optical sensing, spectral analysis and other aspects.

[0005] However, the common FP cavity lasers currently have a long cavity length, usually between several hundred microns and several millimeters, which severely limits their integration. Summary of the invention

[0006] 1. Technical issues to be solved

[0007] The purpose of the present invention is to solve the problem that the FP cavity laser in the prior art has a long cavity length, usually between several hundred microns and several millimeters, which seriously limits its integration, and to propose a metal-confined FP cavity laser for on-chip integration.

[0008] 2. Technical solution

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A metal-limited FP cavity laser for on-chip integration comprises an active semiconductor FP cavity, an optical medium layer, a metal limiting layer, an electrode, a waveguide structure and a bonding layer, wherein the optical medium layer is located at both ends of the semiconductor FP cavity, the metal limiting layer is located at the top of the FP cavity and above the optical medium layers at both ends of the FP cavity, the electrode is connected to the electric injection layer of the FP cavity, and the FP cavity is bonded to the waveguide structure via a transparent bonding layer.

[0011] Preferably, the semiconductor FP cavity is a region for generating laser light, and its operating wavelength is in the visible light and near infrared bands, and the active layer adopts any one of multi-quantum wells, quantum dots, nanowires or other semiconductor materials.

[0012] Preferably, the optical medium layer is a dielectric material, and the dielectric material is any one of dielectric materials such as silicon dioxide, silicon nitride, and aluminum oxide.

[0013] Preferably, the metal confinement layer is a metal material that totally reflects light in the FP cavity, and the metal material includes any one or any combination of gold, aluminum, silver, copper, platinum, palladium, chromium, titanium, and nickel.

[0014] Preferably, the electrode is a metal material for current injection, and the metal material includes any one or any combination of gold, aluminum, silver, copper, platinum, palladium, chromium, titanium, and nickel.

[0015] Preferably, the waveguide structure is used for coupling output of energy, and the waveguide material includes any one of silicon, silicon nitride, quartz, lithium niobate and the like.

[0016] Preferably, the bonding layer is an intermediate layer for bonding the FP cavity and the waveguide structure, and the bonding material is any one of adhesive materials such as benzocyclobutene (BCB), polyimide, epoxy resin, silicone rubber, phenolic adhesive, etc.

[0017] 3. Beneficial effects

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] (1) In the present invention, the Q value of the FP cavity laser is greatly improved by the metal confinement layer, and the size of the laser can be reduced to less than 10 microns, thereby realizing the miniaturization of the FP cavity, which has important application prospects in the fields of on-chip optical interconnection and on-chip integration.

[0020] (2) In the present invention, by changing the structural parameters and adjusting the coupling between the FP cavity resonant mode and the waveguide guided mode, more than 55% of the single-ended coupled output and more than 80% of the double-ended coupled output are achieved.

[0021] (3) In the present invention, the metal-confined FP cavity laser has a large manufacturing tolerance. When the alignment error between the FP cavity and the waveguide is 800nm, the double-ended waveguide coupling output efficiency can still reach about 70%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a FP cavity waveguide coupling structure in a metal-confined FP cavity laser for on-chip integration proposed by the present invention;

[0023] Figure 2 This is a laser spectrum diagram of the FP cavity in a metal-confined FP cavity laser for on-chip integration proposed by the present invention;

[0024] Figure 3 is the Ey field distribution diagram of the z=0 plane proposed in Example 2 of the present invention;

[0025] Figure 4 Graph showing the variation of the coupling output efficiency and the quality factor with the waveguide width proposed in Embodiment 2 of the present invention;

[0026] Figure 5 The Ey field distribution in the y=0 plane when the width of the bidirectional output waveguide proposed in Example 2 of the present invention is 1200 nm;

[0027] Figure 6 The Ey field distribution in the y=0 plane when the width of the single-ended output waveguide proposed in Example 2 of the present invention is 1200 nm;

[0028] Figure 7 Graph showing the coupling efficiency and Q value as a function of BCB thickness proposed in Example 2 of the present invention;

[0029] Figure 8 Graph showing how the coupling efficiency and Q value vary with the alignment deviation dy proposed in Example 2 of the present invention. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0031] Embodiment 1:

[0032] A metal-confined FP cavity laser for on-chip integration, comprising an active semiconductor FP cavity, an optical medium layer, a metal confinement layer, an electrode, a waveguide structure and a bonding layer, wherein the optical medium layer is located at both ends of the semiconductor FP cavity, and the optical medium layer is a dielectric material, and the dielectric material is any one of dielectric materials such as silicon dioxide, silicon nitride, and aluminum oxide;

[0033] In this embodiment, the metal limiting layer is located on the top of the FP cavity and on the optical medium layers at both ends of the FP cavity. The metal limiting layer is a metal material that fully reflects the light in the FP cavity. The metal material includes any one or any combination of gold, aluminum, silver, copper, platinum, palladium, chromium, titanium, and nickel.

[0034] In this embodiment, the semiconductor FP cavity is the area where laser light is generated, and its operating wavelength is in the visible light and near-infrared bands, and the active layer adopts any one of multi-quantum wells, quantum dots, nanowires or other semiconductor materials;

[0035] In this embodiment, the electrode is connected to the electric injection layer of the FP cavity, and the FP cavity and the waveguide structure are bonded through a transparent bonding layer. The electrode is a metal material used for current injection, and the metal material includes any one or any combination of gold, aluminum, silver, copper, platinum, palladium, chromium, titanium, and nickel. The waveguide structure is used for coupled output of energy, and the waveguide material includes any one of silicon, silicon nitride, quartz and other materials. The bonding layer is an intermediate layer for bonding the FP cavity and the waveguide structure, and the bonding material is any one of adhesive materials such as benzocyclobutene, polyimide, epoxy resin, silicone rubber, phenolic adhesive and the like.

[0036] In this embodiment, the Q value of the FP cavity laser is greatly improved by the metal confinement layer, and the size of the laser can be reduced to less than 10 microns, realizing the miniaturization of the FP cavity, which has important application prospects in the fields of on-chip optical interconnection and on-chip integration.

[0037] In this embodiment, by changing the structural parameters and adjusting the coupling between the FP cavity resonant mode and the waveguide guided mode, more than 55% of the single-ended coupled output and more than 80% of the double-ended coupled output are achieved.

[0038] In this embodiment, the metal-confined FP cavity laser has a large manufacturing tolerance. When the alignment error between the FP cavity and the waveguide is 800 nm, the double-end waveguide coupling output efficiency can still reach about 70%.

[0039] Embodiment 2:

[0040] In this embodiment, refer to Figure 1 The semiconductor FP cavity is composed of an InAlGaAs multi-quantum well layer, an InP layer and an InGaAsP electric injection layer. The sidewalls and top of the FP cavity are covered by a metal / dielectric layer. The FP cavity is bonded to the SOI ridge silicon waveguide through BCB (benzocyclobutene).

[0041] In this embodiment, the parameters used are: the length (x direction) of the FP cavity is 6.77 μm, the width is 6 μm; the thickness of the active layer InAlGaAs is 320 nm, the thickness of the cover layer p-InP and n-InP is 250 nm, the thickness of the contact layer p-InGaAsP and n-InGaAsP is 50 nm, the thickness of the dielectric layer silicon dioxide is 200 nm, the thickness of the metal cladding Al is 200 nm, the thickness of benzocyclobutene (the distance from the upper surface of benzocyclobutene to the upper surface of the silicon waveguide ridge) is 100 nm, the inner ridge height of the silicon waveguide is 400 nm, and the outer ridge height is 300 nm;

[0042] In this embodiment, refer to Figure 2-8 In this coupling structure, the resonant wavelength of the FP cavity is 1546nm, and the Ey field distribution in the z=0 plane is as follows: Figure 3 As shown, the field distribution shows that the mode is TE 29,1 model;

[0043] In this embodiment, the coupling structure can achieve efficient coupling output. Figure 4 As shown in the figure, when the bidirectional output waveguide ridge width w changes from 600nm to 1200nm, the coupling output efficiency gradually increases. When w = 1200nm, the bidirectional output waveguide coupling efficiency reaches 75%; in addition, the coupling efficiency of the single-ended output waveguide can also reach 56%. Figure 5 and Figure 6 It can be seen that the energy in the FP cavity is effectively coupled into the SOI waveguide;

[0044] In this embodiment, the coupling structure has a large BCB thickness tolerance, and when the BCB thickness changes from 50nm to 150nm, the coupling output can reach more than 45%;

[0045] In this embodiment, the coupling structure has a large alignment tolerance. When dy changes from 0 to 800 nm, the structure can still achieve a coupling output of about 70%; and when dy=1500 nm, the coupling output efficiency can still reach 60%.

[0046] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A metal-confined FP cavity laser for on-chip integration, comprising an active semiconductor FP cavity, an optical medium layer, a metal confinement layer, an electrode, a waveguide structure and a bonding layer, characterized in that: The optical medium layer is located at both ends of the semiconductor FP cavity, the metal limiting layer is located at the top of the FP cavity and above the optical medium layer at both ends of the FP cavity, the electrode is connected to the electric injection layer of the FP cavity, and the FP cavity is bonded to the waveguide structure through a transparent bonding layer.

2. A metal-confined FP cavity laser for on-chip integration according to claim 1, characterized in that: The semiconductor FP cavity is a region for generating laser light, and its operating wavelength is in the visible light and near infrared bands. The active layer adopts any one of multi-quantum wells, quantum dots, nanowires or other semiconductor materials.

3. A metal-confined FP cavity laser for on-chip integration according to claim 1, characterized in that: The optical medium layer is a medium material, and the medium material is any one of medium materials such as silicon dioxide, silicon nitride, and aluminum oxide.

4. The metal-confined FP cavity laser for on-chip integration according to claim 1, characterized in that: The metal limiting layer is a metal material that fully reflects the light in the FP cavity, and the metal material includes any one or any combination of gold, aluminum, silver, copper, platinum, palladium, chromium, titanium, and nickel.

5. The metal-confined FP cavity laser for on-chip integration according to claim 1, characterized in that: The electrode is a metal material used for current injection, and the metal material includes any one or any combination of gold, aluminum, silver, copper, platinum, palladium, chromium, titanium, and nickel.

6. The metal-confined FP cavity laser for on-chip integration according to claim 1, characterized in that: The waveguide structure is used for coupling output of energy, and the waveguide material includes any one of silicon, silicon nitride, quartz, lithium niobate and the like.

7. The metal-confined FP cavity laser for on-chip integration according to claim 1, characterized in that: The bonding layer is an intermediate layer for bonding the FP cavity and the waveguide structure, and the bonding material is any one of adhesive materials such as benzocyclobutene (BCB), polyimide, epoxy resin, silicone rubber, phenolic adhesive, etc.

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