CN213278692U

CN213278692U - Narrow linewidth laser

Info

Publication number: CN213278692U
Application number: CN202022214888.2U
Authority: CN
Inventors: 鲜青云; 王任凡
Original assignee: Wuhan Minxin Semiconductor Co ltd
Current assignee: Wuhan Minxin Semiconductor Co ltd
Priority date: 2020-09-28
Filing date: 2020-09-28
Publication date: 2021-05-25
Anticipated expiration: 2030-09-28

Abstract

The utility model provides a narrow linewidth laser instrument, narrow linewidth laser instrument include from down limiting layer, InP layer of the substrate, active area under up epitaxial growth's back electrode, InP substrate layer, active area, InGaAsP active area, limiting layer, InP layer and InGaAs contact layer, the InGaAs contact layer is etched deep trench array downwards, and the degree of depth of each deep trench is passed InGaAsP active area, the metal electrode has been plated on the InGaAs contact layer. The utility model discloses a deep etching groove can reduce the scattering loss when light passes through the groove side, reduces the loss outside the chamber, and the output linewidth is narrower, and output light energy density is high.

Description

Narrow linewidth laser

Technical Field

The utility model relates to the field of photoelectric technology, especially, relate to a narrow linewidth laser.

Background

The high transmission rate optical module applied to optical communication has higher and higher requirements on the line width of a light source, in order to obtain a laser device which has narrow line width and can be applied to an optical communication waveband, the currently adopted technology mainly comprises an external cavity laser device and a silicon optical semiconductor laser device, although the two schemes can realize ultra-narrow line width, because the external cavity laser device and the silicon optical semiconductor laser device are composed of a plurality of parts, the problems of high cost, poor stability of an external optical coupling device, insufficient integration and the like exist, and the high transmission rate optical module is not suitable for being applied to an actual optical communication module on a large scale. Semiconductor laser chips with high integration and high stability, such as Distributed Feedback Bragg (DFB) and Distributed Bragg Reflector (DBR) lasers, can also solve the above problems, but because the equivalent cavity length of a semiconductor laser is short, the output linewidth is large, and the linewidth requirements in the optical communication technology cannot be met.

SUMMERY OF THE UTILITY MODEL

The utility model provides a narrow linewidth laser for solve among the prior art defect that the linewidth can not reach the optical communication requirement, realized the narrow linewidth output of laser instrument.

The utility model provides a narrow linewidth laser makes on semiconductor epitaxial wafer, include and restrict layer, InP layer and InGaAs contact layer on follow up epitaxial growth's back electrode, InP substrate layer, active area down, InGaAsP active area, active area down, the InGaAs contact layer has deep trench array, and the degree of depth of each deep trench is passed InGaAsP active area, the metal electrode has been plated on the InGaAs contact layer.

On the basis of the technical scheme, the utility model discloses can also make following improvement.

Optionally, the array of deep trenches comprises 2-6 identical deep trenches.

Optionally, the optical path between the centers of two adjacent deep trenches satisfies an integral multiple of the center wavelength of the quarter laser, and at least one section of the optical path is an even multiple of the center wavelength of the quarter laser.

Optionally, each of the deep trenches has a depth of 4 μm.

The utility model provides a narrow linewidth laser adopts the deep etching groove can reduce the scattering loss when light passes through the groove side, reduces the loss outside the chamber, and the output linewidth is narrower, and output light energy density is high.

Drawings

In order to more clearly illustrate the technical solutions of the present invention or the prior art, the following briefly introduces the drawings required for the embodiments or the prior art descriptions, and obviously, the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a narrow linewidth laser provided by the present invention;

FIG. 2 is a schematic diagram of the distribution of etched deep trenches in a laser;

FIG. 3 is a schematic view of an etched mesa laser;

FIG. 4 is a surface electrode layout;

fig. 5 is a laser emission spectrogram of a narrow linewidth laser of the present invention.

Reference numerals:

1. the back electrode, 2, an InP substrate, 3, an active region lower limiting layer, 4, an InGaAsP active region, 5, an active region upper limiting layer, 6, a p-InP layer, 7, an n-InP layer, 8, an InP covering layer, 9, an InGaAs contact layer, 10, a surface electrode, 11 and a deep groove.

Detailed Description

To make the objects, technical solutions and advantages of the present invention clearer, the drawings of the present invention are combined to clearly and completely describe the technical solutions of the present invention, and obviously, the described embodiments are some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

Based on the background art, the utility model provides a narrow linewidth laser makes on semiconductor epitaxial wafer, see fig. 1, and this narrow linewidth laser includes from down limiting layer 3, InGaAsP active area 4, active area upper limit layer 5, InP overburden 8 and InGaAs contact layer 9 under up epitaxial growth's back electrode 1, InP substrate layer 2, active area down. The InGaAs contact layer 9 is etched downwards to form an array of deep trenches, each deep trench 11 penetrates through the InGaAsP active region 4 in depth, and the InGaAs contact layer 9 is plated with a metal electrode 10.

The deep groove array comprises 2-6 identical deep grooves 11, the optical path between the centers of two adjacent deep grooves 11 meets the integral multiple of the central wavelength of a quarter laser, and at least one section of optical path is even multiple of the central wavelength of the quarter laser.

The single-mode output can be realized through the vernier effect, as shown in fig. 2, the laser is provided with three deep grooves, the three deep grooves form three cavities, the wavelength intervals of the three cavities have slight difference, for the central wavelength lambda of the laser, the three cavities simultaneously meet the resonance condition, and other wavelengths do not meet the resonance condition, so that only the central wavelength lambda of the laser is oscillated in a certain free spectral range, and the single-mode output is realized.

The utility model discloses a deep etching groove can reduce the scattering loss when light passes through the groove side, reduces the loss outside the chamber, and the output linewidth is narrower, and output light energy density is high.

As a possible implementation, as shown in fig. 1 and 3, a p-InP layer 6 and an n-InP layer 7 are double epitaxially grown on both sides of the InGaAsP active region 4 and the confinement layer 5 on the active region, wherein the refractive indices of the p-InP layer 6 and the n-InP layer 7 are different from the refractive indices of the InGaAsP active region 4 and the confinement layer 5 on the active region.

The buried heterojunction is adopted in a manner equivalent to a refractive index waveguide of a heterojunction-like structure laterally established in the active layer, having a large refractive index difference. The area of the InGaAsP active region 4 is reduced, the limiting effect on an optical field is enhanced, the consumption of optical propagation is reduced, the spatial distribution stability of the optical field is high, the optical energy density is improved, and the pumping threshold is reduced.

The following describes a method for manufacturing a narrow linewidth laser, which mainly includes the following steps:

step 1: and epitaxially growing an active region lower limiting layer 3 on the n-type InP substrate layer 2.

Step 2: a multi-quantum well MQW of InGaAsP is grown on the active region lower confinement layer 3 as an active region, i.e., an InGaAsP active region 4.

And step 3: an active region upper confinement layer 5 is epitaxially grown over the InGaAsP active region 4.

And 4, step 4: depositing a layer of SiO on the confinement layer 5 above the active region₂Performing a photolithography with SiO₂Protecting the desired waveguide pattern, using HCl and H for the other parts₂SO₄The upper limit layer 5 of the active region and the InGaAsP active region 4 are respectively matched with an etching solution, and the epitaxial wafer is etched to have a structure as shown in a schematic diagram of FIG. 3.

And 5: secondary epitaxial growth is performed to form an inverted PN junction by growing a p-type InP layer 6 and an n-type InP layer 7 on both sides of a mesa (the structure in fig. 3 is referred to as a mesa) to confine electrons and carriers.

Step 6: removing the remaining SiO₂And then an InP covering layer 8 and an InGaAs contact layer 9 with the thickness of 200-250 nm are grown, so that the metal electrode of the laser and the chip are in good ohmic contact.

After the step 6, completing the epitaxial growth part of the laser, performing secondary photoetching, and etching the deep groove 11, wherein the deep groove 11 can adopt an etching formula based on four gases of argon, hydrogen, methane and chlorine, and the proportion is 5: 5: 10: and 7, obtaining a deep etching groove with smooth and vertical side walls and a deep etching reflecting surface at the temperature of 60 ℃, wherein the etching depth is about 4 mu m and exceeds the quantum well active region.

And after the deep groove is manufactured, carrying out photoetching for three times, plating a metal electrode 10 on the upper surface of the platform, arranging the metal on the upper surface as shown in figure 4, finally thinning the whole epitaxial wafer to manufacture an n-surface electrode, and plating an AR (anti-reflection) film and an HR (high-reflection) film on two sections respectively after cleavage. The coated strip is cleaved into single tubes, and then a subsequent packaging test can be carried out, wherein the laser emergent light spectrum of the manufactured narrow-linewidth laser is shown in figure 5, wherein the abscissa is wavelength and nm; the ordinate is intensity, in dBm.

The utility model provides a narrow linewidth laser adopts the deep etching groove can reduce the scattering loss when light passes through the groove side, reduces the extraluminal loss. The buried heterojunction is adopted in a manner equivalent to a refractive index waveguide of a heterojunction-like structure laterally established in the active layer, having a large refractive index difference. The area of the active region is reduced, the limiting effect on the optical field is enhanced, the consumption of optical transmission is reduced, and the spatial distribution stability of the optical field is high, so that the optical energy density is improved, and the pumping threshold is reduced.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention in its corresponding aspects.

Claims

1. A narrow linewidth laser is manufactured on a semiconductor epitaxial wafer and is characterized by comprising a back electrode, an InP substrate layer, an active region lower limiting layer, an InGaAsP active region, an active region upper limiting layer, an InP covering layer and an InGaAs contact layer which are epitaxially grown from bottom to top, wherein the InGaAs contact layer is etched downwards to form a deep groove array, the depth of each deep groove penetrates through the InGaAsP active region, and a metal electrode is plated on the InGaAs contact layer.

2. The narrow linewidth laser of claim 1, wherein the array of deep trenches comprises 2-6 identical deep trenches.

3. The narrow linewidth laser according to claim 1 or 2, wherein the optical path length between the centers of two adjacent deep trenches satisfies an integer multiple of the center wavelength of the quarter laser, and wherein at least one optical path length is an even multiple of the center wavelength of the quarter laser.

4. The narrow linewidth laser according to claim 1 or 2, wherein each of the deep trenches has a depth of 4 μm.

5. The narrow linewidth laser of claim 1, wherein the InGaAsP active region and the confinement layer over the active region are bi-epitaxially grown with a p-InP layer and an n-InP layer on both sides of the active region, wherein the p-InP layer and the n-InP layer have refractive indices that differ by a large amount from the refractive indices of the InGaAsP active region and the confinement layer over the active region.