High-linearity low-noise semiconductor laser

Abstract

The utility model relates to the technical field of gas detection of laser sensing, in particular to a high-linearity low-noise semiconductor laser which comprises a laser body, and a semiconductor laser chip and an optical isolator are arranged in the laser body. The central axis of the optical isolator and the main optical axis of the semiconductor laser chip are in a coaxial state, a coaxial state but a rotation angle state or an inclined off-axis state, so that reflected light and stray light generated in a laser body and an optical link can be isolated and directionally scattered; light noise generated by reflected light and stray light in a laser body or an optical link is reduced, and the linearity of the laser body is improved. According to the utility model, the optical noise in the laser body and the optical link can be reduced, the precision, the stability and the reliability of the laser gas sensor are improved, and the applicability and the universality under various different environments and working conditions are realized.

Description

Technical Field

[0001] The utility model relates to the technical field of gas detection by laser sensing, in particular to a semiconductor laser with high linearity and low noise. Background Art

[0002] The real-time online gas content detection system based on TDLAS (tunable semiconductor laser absorption spectroscopy) technology measures the content of the corresponding gas through the gas's absorption of lasers of a specific wavelength. It is an advanced new generation of gas detection technology with high sensitivity and fast response. This technology has high measurement accuracy, up to the ppm (parts per million) level; high accuracy, capable of detecting specific component gases in mixed gases; fast response speed, up to the millisecond response level; using laser detection, it has anti-interference and explosion-proof characteristics, and can be used for flammable and explosive gas detection.

[0003] To achieve high-precision measurement, it is necessary to ensure that the noise in the laser and optical link in the laser detection system is as small as possible. Taking the existing common products as an example, in the laser detection system, from the laser output light to the detector receiving light, the entire optical link mainly includes lasers, detectors, gas chambers, optical fibers, and passive optical devices used to connect the optical links. Then the noise generated in the entire optical link comes from the noise of the laser body as a light source, and the optical noise generated by the connection interface when all the passive optical devices in the above optical links are connected to each other. For example, in addition to the effective light output inside the laser body, there is also reflected light caused by the lens group, and reflected light generated between the interface end faces of various passive optical devices in the optical link. These reflected lights will always exist in the entire optical link, and gradually generate optical noise formed by optical interference, resulting in an increase in optical noise in the optical link and a decrease in the signal-to-noise ratio, which directly affects the precision and accuracy of laser gas sensor detection. In severe cases, it may even cause false alarms or downtime of the detection equipment.

[0004] At present, there are several main problems with the laser body and optical link in the field of laser sensing gas detection:

[0005] 1. In the process of packaging the laser chip inside the semiconductor laser body for sensing, according to the principle of light refraction and reflection, when the light path passes through different media, refracted light and reflected light will be generated. The refracted light continues to be output on the main optical axis as an effective light path, while the reflected light will be partially reflected into the laser chip, forming optical noise, affecting the normal operation of the laser chip and causing the performance of the laser chip to decrease;

[0006] 2. In the optical link of the detection system of semiconductor lasers for sensing, the number and type of passive optical devices in the optical link vary depending on the customer's usage scenarios. When the laser beam emitted by the semiconductor laser is transmitted in the optical link, the reflected light generated when passing through the passive optical devices step by step will be repeatedly transmitted along the transmission direction of the optical link, forming optical interference, causing the optical noise in the optical link to increase, affecting the precision and accuracy of the laser detection for sensing. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the prior art, the utility model provides a semiconductor laser with high linearity and low noise, which can at least solve some of the defects in the above-mentioned prior art.

[0008] To achieve the above-mentioned purpose, the technical solution of the utility model is a high-linearity and low-noise semiconductor laser, including a laser body, in which a semiconductor laser chip and an optical isolator are arranged, and the central axis of the optical isolator is in a coaxial state, a coaxial but rotated angle state, or a tilted eccentric state with the main optical axis of the semiconductor laser chip.

[0009] As one of the implementation modes, the isolator includes a magnetic ring and a Faraday square rotating mirror. The magnetic ring is provided with a square inner hole, and the Faraday square rotating mirror is fixed in the square inner hole.

[0010] As one of the implementation modes, one side of the square inner hole extends to the outer peripheral surface of the magnetic ring.

[0011] As one of the implementation modes, the magnetic ring outer sleeve is provided with a metal steel ring.

[0012] As one of the embodiments, the semiconductor laser is a coaxial packaged laser, the laser body includes a TO tube seat and a TO tube body, one end of the TO tube body is fixed on the top surface of the TO tube seat, the semiconductor laser chip is arranged on the top surface of the TO tube seat in the TO tube body, and the optical isolator is arranged in the light outlet end of the TO tube body.

[0013] As one of the implementation modes, the semiconductor laser is a planar package type laser, the laser body includes a laser housing, and the semiconductor laser chip and the optical isolator are both disposed in the laser housing.

[0014] Compared with the prior art, the utility model has the following beneficial effects:

[0015] (1) The utility model installs an optical isolator between the semiconductor laser chip in the laser body and the light outlet of the laser body, and adjusts the central axis of the optical isolator to be coaxial with the main optical axis of the semiconductor laser chip. The optical isolator can effectively suppress the reflected light generated from the far end in the optical link from returning to the resonant cavity of the semiconductor laser chip, thereby avoiding the problem of mode hopping and linear kinking of the output light of the semiconductor laser chip, thereby ensuring the stability of the working state of the semiconductor laser chip, reducing the noise caused by optical interference generated by the reflected light of the semiconductor laser, and improving the laser output characteristics of the semiconductor laser;

[0016] (2) The utility model adjusts the central axis of the optical isolator to be coaxial with the main optical axis of the semiconductor laser chip but rotated at an angle, so that the main optical axes of the optical isolator and the semiconductor laser chip can be actively aligned with the polarization states of both parties, so that the largest number of light beams in the semiconductor laser chip penetrate the optical isolator and are emitted, thereby further reducing the optical noise formed by the reflected light generated by the optical isolator body in the semiconductor laser, further improving the linearity of the laser, and at the same time reducing the reflected light generated by the optical isolator entering the optical link, reducing the optical noise of the optical link, and improving the sensitivity and stability of the laser gas sensor;

[0017] (3) The utility model adjusts the central axis of the optical isolator to be in an inclined off-axis state with respect to the main optical axis of the semiconductor laser chip, which can not only maintain the further reduction of the reflected light generated by the optical isolator body in the semiconductor laser, but also actively scatter the reflected light generated by the remote passive optical device in the optical link out of the main optical axis by adjusting the inclined off-axis state of the isolator, thereby improving the linearity of the laser on the one hand, and actively reducing the optical link noise formed by the reflected light generated by the remote passive optical device in the optical link on the other hand, further improving the sensitivity and stability of the overall laser gas sensor;

[0018] (4) The optical isolator in the utility model is installed and debugged through an active online test installation method, which ensures that the reflected light generated from the far end of the optical link will not return to the optical link again after returning to the optical isolator, thereby avoiding the reflected light beam from reflecting back and forth in the optical link, oscillating back and forth, and forming optical interference with the incident light beam to cause optical noise of the system, thereby improving the sensitivity and stability of the laser gas sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1-Figure 3 A schematic diagram of a coaxial packaged semiconductor laser with high linearity and low noise for spatial light output provided by an embodiment of the utility model, wherein the central axis of the optical isolator and the main optical axis of the semiconductor laser chip are respectively in a coaxial state, a coaxial but rotated angle state, and a tilted off-axis state;

[0021] Figure 4-Figure 6 A schematic diagram of a high-linearity, low-noise, coaxial packaged semiconductor laser with optical fiber output provided by an embodiment of the utility model, wherein the central axis of the optical isolator and the main optical axis of the semiconductor laser chip are respectively in a coaxial state, a coaxial but rotated angle state, and a tilted off-axis state;

[0022] Figure 7-Figure 9 A schematic diagram of a planar packaged semiconductor laser with high linearity and low noise for spatial light output provided by an embodiment of the utility model, wherein the central axis of the optical isolator and the main optical axis of the semiconductor laser chip are respectively in a coaxial state, a coaxial but rotated angle state, and a tilted off-axis state;

[0023] Figure 10-12 A schematic diagram of a high-linearity, low-noise planar package semiconductor laser with optical fiber output provided by an embodiment of the utility model, wherein the central axis of the optical isolator and the main optical axis of the semiconductor laser chip are respectively in a coaxial state, a coaxial but rotated angle state, and a tilted off-axis state;

[0024] Fig.13 A schematic diagram of an optical isolator without a metal steel ring provided in an embodiment of the utility model;

[0025] Fig.14 A schematic diagram of an optical isolator with a metal steel ring provided in an embodiment of the utility model;

[0026] In the figure: 1. semiconductor laser chip; 2. lens group; 3. optical isolator; 31. Faraday square rotating lens; 32. magnetic ring; 33. metal steel ring; 4. TO tube socket; 5. TO tube body; 6. laser housing; 7. adjustment ring; 8. optical fiber assembly. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0029] Embodiment 1

[0030] The present embodiment provides a semiconductor laser with high linearity and low noise, comprising a laser body, wherein a semiconductor laser chip 1 and an optical isolator 3 are arranged in the laser body, and the central axis of the optical isolator 3 is in a coaxial state, a coaxial state but in a rotation angle state, or a tilted eccentric state with the main optical axis of the semiconductor laser chip 1.

[0031] In one embodiment, the central axis of the optical isolator 3 is coaxial with the main optical axis of the semiconductor laser chip 1. The coaxial state means that the central axis of the optical isolator 3 is in the same straight line with the main optical axis of the semiconductor laser chip 1, and the positioning mark on the optical isolator 3 is aligned with the positioning mark on the laser body, so that the polarization direction of the polarizer of the optical isolator 3 is consistent with the polarization direction of the semiconductor laser chip 1. By installing the optical isolator 3 between the semiconductor laser chip 1 in the laser body and the light outlet of the laser body, due to the unidirectional path characteristics of the optical isolator 3, the reflected light generated from the far end in the optical link can be effectively suppressed from returning to the resonant cavity of the semiconductor laser chip 1, avoiding the problem of mode hopping and linear kinking of the semiconductor laser chip 1, thereby ensuring the stability of the working state of the semiconductor laser chip 1, reducing the noise caused by the optical interference of the semiconductor laser due to the reflected light, and improving the laser output characteristics of the semiconductor laser.

[0032] In one embodiment, the central axis of the optical isolator 3 is coaxial with the main optical axis of the semiconductor laser chip 1 but rotated at an angle. The coaxial but rotated angle state means that the central axis of the optical isolator 3 is in the same straight line with the main optical axis of the semiconductor laser chip 1, and the positioning mark on the optical isolator 3 is rotated at a certain angle relative to the positioning mark on the laser body, so that the polarization direction of the polarizer of the optical isolator 3 is consistent with the polarization direction of the semiconductor laser chip 1. Since the optical isolator 3 and the main optical axis of the semiconductor laser chip 1 are coaxial but rotated at an angle, the polarization states of both parties can be actively aligned, so that the most light beams in the semiconductor laser chip 1 penetrate the optical isolator 3 and emit, thereby further reducing the optical noise formed by the reflected light generated by the optical isolator 3 body in the semiconductor laser, further improving the linearity of the laser, and at the same time, reducing the reflected light generated by the optical isolator 3 entering the optical link, reducing the optical noise of the optical link, and improving the sensitivity and stability of the laser gas sensor.

[0033] In another embodiment, the central axis of the optical isolator 3 is in a tilted off-axis state with the main optical axis of the semiconductor laser chip 1. The tilted off-axis state refers to the central axis of the optical isolator 3 and the main optical axis of the semiconductor laser chip 1 being in a tilted intersecting state, so that the polarization direction of the polarizer of the optical isolator 3 is consistent with the polarization direction of the semiconductor laser chip 1. Since the optical isolator 3 and the main optical axis of the semiconductor laser chip 1 can form a tilted off-axis state, it can not only maintain the further reduction of the reflected light generated by the optical isolator 3 body in the semiconductor laser, but also adjust the tilted off-axis state of the isolator to further actively scatter the reflected light generated by the remote passive optical device in the optical link out of the main optical axis, thereby improving the linearity of the laser on the one hand, and actively reducing the optical link noise formed by the reflected light generated by the remote passive optical device in the optical link on the other hand, further improving the sensitivity and stability of the overall laser gas sensor.

[0034] Furthermore, a lens group 2 is also arranged on the main optical axis of the optical path in the laser body, and the lens group 2 is located between the semiconductor laser chip 1 and the optical isolator 3. The lens group 2 includes a single lens or a lens group 2 formed by combining multiple lenses.

[0035] In this embodiment, the lens group 2 is any one of a converging light lens group 2, a diverging light lens group 2 and a collimating light lens group 2. Different semiconductor lasers can be formed by using different lens groups 2. Specifically, when the lens group 2 uses a converging light lens group 2, the semiconductor laser is a converging light semiconductor laser; when the lens group 2 uses a diverging light lens group 2, the semiconductor laser is a diverging light semiconductor laser; when the lens group 2 uses a collimating light lens group 2, the semiconductor laser is a collimating light semiconductor laser.

[0036] Furthermore, the isolator is a single-polarized light isolator 3 or a multi-polarized light isolator 3. The single-polarized light isolator 3 has a lower cost, and the multi-polarized light isolator 3, such as a double-polarized light isolator 3, has a better isolation effect.

[0037] This embodiment also provides a method for manufacturing the above-mentioned high-linearity and low-noise semiconductor laser, comprising the following steps:

[0038] S1, install the optical isolator 3 into the laser body, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0039] S2, pre-fixing the optical isolator 3;

[0040] S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the output light index of the semiconductor laser;

[0041] S4, judging whether the output light index of the semiconductor laser is optimal, if it is optimal, executing step S5; if it is not optimal, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the output light of the semiconductor laser is optimal, and then executing step S5;

[0042] S5. Completely fix the optical isolator 3.

[0043] When the central axis of the optical isolator 3 is coaxial with the main optical axis of the semiconductor laser chip 1 , the indicator of the semiconductor laser output light tested in step S3 is the light intensity.

[0044] When the central axis of the optical isolator 3 is coaxial with the main optical axis of the semiconductor laser chip 1 but is rotated at an angle, the indicators of the semiconductor laser output light tested in step S3 are the light intensity and linearity.

[0045] When the central axis of the optical isolator 3 is in an inclined off-axis state with respect to the main optical axis of the semiconductor laser chip 1 , the indicators of the semiconductor laser output light tested in step S3 are the light intensity, linearity and optical link noise.

[0046] In this embodiment, the pre-fixation and complete fixation of the optical isolator 3 can be performed by any one of laser welding, energy storage welding, metal solder welding and adhesive curing.

[0047] In this embodiment, the optical isolator 3 is installed and debugged by an active online test installation method, which ensures that the reflected light generated from the far end in the optical link will not return to the optical link again after returning to the optical isolator 3, thereby avoiding the reflected light beam from reflecting back and forth in the optical link, oscillating back and forth, and forming optical interference with the incident light beam to cause optical noise of the system, thereby improving the sensitivity and stability of the laser gas sensor.

[0048] Embodiment 2

[0049] Continuing with the high-linearity and low-noise semiconductor laser provided in Example 1, the semiconductor laser is a coaxial packaged laser, and the light output interface type of the semiconductor laser adopts a spatial light output type; the laser body includes a TO tube seat 4 and a TO tube body 5, one end of the TO tube body 5 is fixed on the top surface of the TO tube seat 4, the semiconductor laser chip 1 is arranged on the top surface of the TO tube seat 4 in the TO tube body 5, the optical isolator 3 is arranged in the light output end of the TO tube body 5, and the lens group 2 is arranged in the TO tube body 5 and is located between the semiconductor laser chip 1 and the optical isolator 3.

[0050] The following uses the collimating light lens group 2 as an example to illustrate the method for manufacturing the high-linearity and low-noise semiconductor laser of this embodiment.

[0051] like Figure 1 As shown, when the central axis of the optical isolator 3 is coaxial with the main optical axis of the semiconductor laser chip 1, the method for manufacturing a high-linearity and low-noise semiconductor laser of this embodiment includes the following steps:

[0052] S1. Install the optical isolator 3 into the groove of the TO tube body 5, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0053] S2, using UV glue to pre-fix the optical isolator 3 with the adjusted polarization direction and the TO tube body 5;

[0054] S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the light intensity of the semiconductor laser output light;

[0055] S4, judging whether the light intensity of the semiconductor laser output light is optimal, if it is optimal, executing step S5; if it is not optimal, removing the pre-cured UV glue, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the light intensity of the semiconductor laser output light is optimal, and then executing step S5;

[0056] S5. Completely glue and fix the optical isolator 3 in the TO tube body 5.

[0057] like Figure 2 As shown, when the central axis of the optical isolator 3 is coaxial with the main optical axis of the semiconductor laser chip 1 but in a rotated angle state, the method for manufacturing a high linearity and low noise semiconductor laser of this embodiment includes the following steps:

[0058] S1. Install the optical isolator 3 into the groove of the TO tube body 5, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0059] S2, using UV glue to pre-fix the optical isolator 3 with the adjusted polarization direction and the TO tube body 5;

[0060] S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the light intensity of the semiconductor laser output light;

[0061] S4, judging whether the light intensity index of the semiconductor laser output light is optimal, if it is optimal, executing step S5; if it is not optimal, removing the pre-cured UV ultraviolet glue, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the light intensity index of the semiconductor laser output light is optimal, and then executing step S5;

[0062] S5, keeping the optical isolator 3 at the position where the light intensity index of the semiconductor laser output light is optimal, and testing the linearity of the semiconductor laser output light;

[0063] S6, judging whether the linearity index of the semiconductor laser output light is optimal, if it is optimal, executing step S7; if it is not optimal, removing the pre-cured UV glue, releasing the pre-fixation of the optical isolator 3, coaxially rotating the optical isolator 3, repeating steps S2 and S5, until the linearity index of the semiconductor laser output light is optimal, and then executing step S7;

[0064] S7, completely glue and fix the optical isolator 3 in the TO tube body 5.

[0065] like Figure 3 As shown, when the central axis of the optical isolator 3 is in an inclined off-axis state with respect to the main optical axis of the semiconductor laser chip 1, the method for manufacturing a semiconductor laser with high linearity and low noise in this embodiment includes the following steps:

[0066] S1. Install the optical isolator 3 into the groove of the TO tube body 5, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0067] S2, using UV glue to pre-fix the optical isolator 3 with the adjusted polarization direction and the TO tube body 5;

[0068] S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the light intensity of the semiconductor laser output light;

[0069] S4, judging whether the light intensity index of the semiconductor laser output light is optimal, if it is optimal, executing step S5; if it is not optimal, removing the pre-cured UV ultraviolet glue, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the light intensity index of the semiconductor laser output light is optimal, and then executing step S5;

[0070] S5, keeping the optical isolator 3 at the position where the light intensity index of the semiconductor laser output light is optimal, and testing the linearity of the semiconductor laser output light;

[0071] S6, judging whether the linearity index of the semiconductor laser output light is optimal, if it is optimal, executing step S7; if it is not optimal, removing the pre-cured UV glue, releasing the pre-fixation of the optical isolator 3, coaxially rotating the optical isolator 3, repeating steps S2 and S5, until the linearity index of the semiconductor laser output light is optimal, and then executing step S7;

[0072] S7, keeping the optical isolator 3 at a position where the light intensity and linearity of the semiconductor laser output light are optimal, and testing the optical link noise of the semiconductor laser output light;

[0073] S8, judging whether the optical link noise index of the semiconductor laser output light is optimal, if it is optimal, executing step S9; if it is not optimal, removing the pre-cured UV ultraviolet glue, releasing the pre-fixation of the optical isolator 3, tilting and eccentrically adjusting the optical isolator 3, repeating steps S2 and S7, until the optical link noise index of the semiconductor laser output light is optimal, and then executing step S9;

[0074] S9, completely glue and fix the optical isolator 3 in the TO tube body 5.

[0075] Embodiment 3

[0076] Continuing with the high linearity and low noise semiconductor laser provided in Example 1, the semiconductor laser is a coaxial packaged laser, and the light output interface type of the semiconductor laser adopts a pigtail optical fiber output type; the laser body comprises a TO tube seat 4, a TO tube body 5, an adjustment ring 7 and an optical fiber assembly 8, one end of the TO tube body 5 is fixed on the top surface of the TO tube seat 4, the semiconductor laser chip 1 is arranged on the top surface of the TO tube seat 4 in the TO tube body 5, the optical isolator 3 is arranged in the light output end of the TO tube body 5, the lens group 2 is arranged in the TO tube body 5 and is located between the semiconductor laser chip 1 and the optical isolator 3; the adjustment ring 7 is fixed on the light output end of the TO tube body 5, and the optical fiber assembly 8 is fixed in the adjustment ring 7.

[0077] The method for manufacturing a semiconductor laser with high linearity and low noise of this embodiment is described below by taking the lens group 2 as an example of using a converging light lens group 2 .

[0078] like Figure 4 As shown, when the central axis of the optical isolator 3 is coaxial with the main optical axis of the semiconductor laser chip 1, the method for manufacturing a high-linearity and low-noise semiconductor laser of this embodiment includes the following steps:

[0079] S1. Install the optical isolator 3 into the groove of the TO tube body 5, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0080] S2, using UV glue to pre-fix the optical isolator 3 with the adjusted polarization direction and the TO tube body 5;

[0081] S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the light intensity of the semiconductor laser output light;

[0082] S4, judging whether the light intensity of the semiconductor laser output light is optimal, if it is optimal, executing step S5; if it is not optimal, removing the pre-cured UV glue, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the light intensity of the semiconductor laser output light is optimal, and then executing step S5;

[0083] S5, completely glue and fix the optical isolator 3 in the TO tube body 5;

[0084] S6, placing the adjustment ring 7 on the light outlet end of the TO tube body 5, inserting the optical fiber assembly 8 into the through hole of the adjustment ring 7, and performing active coupling by adjusting in the X, Y, and Z directions to couple the light beam emitted by the semiconductor laser chip 1 into the optical fiber assembly 8;

[0085] S7, fixing the coupled optical fiber assembly 8 to the TO tube body 5 and the adjustment ring 7, and the fixing method can be any one of laser welding, energy storage welding, metal solder welding and adhesive curing.

[0086] like Figure 5 As shown, when the central axis of the optical isolator 3 is coaxial with the main optical axis of the semiconductor laser chip 1 but in a rotated angle state, the method for manufacturing a high linearity and low noise semiconductor laser of this embodiment includes the following steps:

[0087] S1. Install the optical isolator 3 into the groove of the TO tube body 5, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0088] S2, using UV glue to pre-fix the optical isolator 3 with the adjusted polarization direction and the TO tube body 5;

[0089] S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the light intensity of the semiconductor laser output light;

[0090] S4, judging whether the light intensity index of the semiconductor laser output light is optimal, if it is optimal, executing step S5; if it is not optimal, removing the pre-cured UV ultraviolet glue, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the light intensity index of the semiconductor laser output light is optimal, and then executing step S5;

[0091] S5, keeping the optical isolator 3 at the position where the light intensity index of the semiconductor laser output light is optimal, and testing the linearity of the semiconductor laser output light;

[0092] S6, judging whether the linearity index of the semiconductor laser output light is optimal, if it is optimal, executing step S7; if it is not optimal, removing the pre-cured UV glue, releasing the pre-fixation of the optical isolator 3, coaxially rotating the optical isolator 3, repeating steps S2 and S5, until the linearity index of the semiconductor laser output light is optimal, and then executing step S7;

[0093] S7, completely glue and fix the optical isolator 3 in the TO tube body 5;

[0094] S8, placing the adjustment ring 7 on the light outlet end of the TO tube body 5, inserting the optical fiber assembly 8 into the through hole of the adjustment ring 7, and performing active coupling by adjusting in the X, Y, and Z directions to couple the light beam emitted by the semiconductor laser chip 1 into the optical fiber assembly 8;

[0095] S9, fixing the coupled optical fiber assembly 8 to the TO tube body 5 and the adjustment ring 7, and the fixing method can be any one of laser welding, energy storage welding, metal solder welding and adhesive curing.

[0096] like Figure 6 As shown, when the central axis of the optical isolator 3 is in an inclined off-axis state with respect to the main optical axis of the semiconductor laser chip 1, the method for manufacturing a semiconductor laser with high linearity and low noise in this embodiment includes the following steps:

[0097] S1. Install the optical isolator 3 into the groove of the TO tube body 5, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0098] S2, using UV glue to pre-fix the optical isolator 3 with the adjusted polarization direction and the TO tube body 5;

[0099] S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the light intensity of the semiconductor laser output light;

[0100] S4, judging whether the light intensity index of the semiconductor laser output light is optimal, if it is optimal, executing step S5; if it is not optimal, removing the pre-cured UV ultraviolet glue, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the light intensity index of the semiconductor laser output light is optimal, and then executing step S5;

[0101] S5, keeping the optical isolator 3 at the position where the light intensity index of the semiconductor laser output light is optimal, and testing the linearity of the semiconductor laser output light;

[0102] S6, judging whether the linearity index of the semiconductor laser output light is optimal, if it is optimal, executing step S7; if it is not optimal, removing the pre-cured UV glue, releasing the pre-fixation of the optical isolator 3, coaxially rotating the optical isolator 3, repeating steps S2 and S5, until the linearity index of the semiconductor laser output light is optimal, and then executing step S7;

[0103] S7, keeping the optical isolator 3 at a position where the light intensity and linearity of the semiconductor laser output light are optimal, and testing the optical link noise of the semiconductor laser output light;

[0104] S8, judging whether the optical link noise index of the semiconductor laser output light is optimal, if it is optimal, executing step S9; if it is not optimal, removing the pre-cured UV ultraviolet glue, releasing the pre-fixation of the optical isolator 3, tilting and eccentrically adjusting the optical isolator 3, repeating steps S2 and S7, until the optical link noise index of the semiconductor laser output light is optimal, and then executing step S9;

[0105] S9, completely glue and fix the optical isolator 3 in the TO tube body 5;

[0106] S10, placing the adjustment ring 7 on the light outlet end of the TO tube body 5, inserting the optical fiber assembly 8 into the through hole of the adjustment ring 7, and performing active coupling by adjusting in the X, Y, and Z directions to couple the light beam emitted by the semiconductor laser chip 1 into the optical fiber assembly 8;

[0107] S11, fixing the coupled optical fiber assembly 8 to the TO tube body 5 and the adjustment ring 7, and the fixing method can be any one of laser welding, energy storage welding, metal solder welding and adhesive curing.

[0108] Embodiment 4

[0109] Continuing with the high-linearity and low-noise semiconductor laser provided in Example 1, the semiconductor laser is a planar packaged laser, and the light output interface type of the semiconductor laser adopts a spatial light output type; the laser body includes a laser housing 6, and the semiconductor laser chip 1, the lens group 2 and the optical isolator 3 are all arranged in the laser housing 6.

[0110] The following uses the collimating light lens group 2 as an example to illustrate the method for manufacturing the high-linearity and low-noise semiconductor laser of this embodiment.

[0111] like Figure 7 As shown, when the central axis of the optical isolator 3 is coaxial with the main optical axis of the semiconductor laser chip 1, the method for manufacturing a high-linearity and low-noise semiconductor laser of this embodiment includes the following steps:

[0112] S1, install the optical isolator 3 into the laser housing 6, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0113] S2, using UV glue to pre-fix the optical isolator 3 with the polarization direction adjusted and the laser housing 6;

[0114] S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the light intensity of the semiconductor laser output light;

[0115] S4, judging whether the light intensity of the semiconductor laser output light is optimal, if it is optimal, executing step S5; if it is not optimal, removing the pre-cured UV glue, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the light intensity of the semiconductor laser output light is optimal, and then executing step S5;

[0116] S5. Completely glue and fix the optical isolator 3 in the laser housing 6.

[0117] like Figure 8 As shown, when the central axis of the optical isolator 3 is coaxial with the main optical axis of the semiconductor laser chip 1 but in a rotated angle state, the method for manufacturing a high linearity and low noise semiconductor laser of this embodiment includes the following steps:

[0118] S1, install the optical isolator 3 into the laser housing 6, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0119] S2, using UV glue to pre-fix the optical isolator 3 with the polarization direction adjusted and the laser housing 6;

[0120] S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the light intensity of the semiconductor laser output light;

[0121] S4, judging whether the light intensity index of the semiconductor laser output light is optimal, if it is optimal, executing step S5; if it is not optimal, removing the pre-cured UV ultraviolet glue, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the light intensity index of the semiconductor laser output light is optimal, and then executing step S5;

[0122] S5, keeping the optical isolator 3 at the position where the light intensity index of the semiconductor laser output light is optimal, and testing the linearity of the semiconductor laser output light;

[0123] S6, judging whether the linearity index of the semiconductor laser output light is optimal, if it is optimal, executing step S7; if it is not optimal, removing the pre-cured UV glue, releasing the pre-fixation of the optical isolator 3, coaxially rotating the optical isolator 3, repeating steps S2 and S5, until the linearity index of the semiconductor laser output light is optimal, and then executing step S7;

[0124] S7, completely glue and fix the optical isolator 3 in the laser housing 6.

[0125] like Fig. 9 As shown, when the central axis of the optical isolator 3 is in an inclined off-axis state with respect to the main optical axis of the semiconductor laser chip 1, the method for manufacturing a semiconductor laser with high linearity and low noise in this embodiment includes the following steps:

[0126] S1, install the optical isolator 3 into the laser housing 6, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0127] S2, using UV glue to pre-fix the optical isolator 3 with the polarization direction adjusted and the laser housing 6;

[0128] S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the light intensity of the semiconductor laser output light;

[0129] S4, judging whether the light intensity index of the semiconductor laser output light is optimal, if it is optimal, executing step S5; if it is not optimal, removing the pre-cured UV ultraviolet glue, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the light intensity index of the semiconductor laser output light is optimal, and then executing step S5;

[0130] S5, keeping the optical isolator 3 at the position where the light intensity index of the semiconductor laser output light is optimal, and testing the linearity of the semiconductor laser output light;

[0131] S6, judging whether the linearity index of the semiconductor laser output light is optimal, if it is optimal, executing step S7; if it is not optimal, removing the pre-cured UV glue, releasing the pre-fixation of the optical isolator 3, coaxially rotating the optical isolator 3, repeating steps S2 and S5, until the linearity index of the semiconductor laser output light is optimal, and then executing step S7;

[0132] S7, keeping the optical isolator 3 at a position where the light intensity and linearity of the semiconductor laser output light are optimal, and testing the optical link noise of the semiconductor laser output light;

[0133] S8, judging whether the optical link noise index of the semiconductor laser output light is optimal, if it is optimal, executing step S9; if it is not optimal, removing the pre-cured UV ultraviolet glue, releasing the pre-fixation of the optical isolator 3, tilting and eccentrically adjusting the optical isolator 3, repeating steps S2 and S7, until the optical link noise index of the semiconductor laser output light is optimal, and then executing step S9;

[0134] S9, completely glue and fix the optical isolator 3 in the laser housing 6.

[0135] Embodiment 5

[0136] Continuing with the high-linearity and low-noise semiconductor laser provided in Example 1, the semiconductor laser is a coaxial packaged laser, and the optical output interface type of the semiconductor laser adopts a pigtail optical fiber output type; the laser body includes a laser housing 6 and an optical fiber assembly 8, the semiconductor laser chip 1, the lens group 2 and the optical isolator 3 are all arranged in the laser housing 6, and the optical fiber assembly 8 is fixed on the light output port of the laser housing 6.

[0137] The method for manufacturing a semiconductor laser with high linearity and low noise of this embodiment is described below by taking the lens group 2 as an example of using a converging light lens group 2 .

[0138] like Fig.10 As shown, when the central axis of the optical isolator 3 is coaxial with the main optical axis of the semiconductor laser chip 1, the method for manufacturing a high-linearity and low-noise semiconductor laser of this embodiment includes the following steps:

[0139] S1, install the optical isolator 3 into the laser housing 6, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0140] S2, using UV glue to pre-fix the optical isolator 3 with the polarization direction adjusted and the laser housing 6;

[0141] S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the light intensity of the semiconductor laser output light;

[0142] S4, judging whether the light intensity of the semiconductor laser output light is optimal, if it is optimal, executing step S5; if it is not optimal, removing the pre-cured UV glue, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the light intensity of the semiconductor laser output light is optimal, and then executing step S5;

[0143] S5, completely glue and fix the optical isolator 3 in the laser housing 6;

[0144] S6, insert the optical fiber assembly 8 into the through hole of the light outlet of the laser housing 6, and perform active coupling by adjusting in the X, Y, and Z directions to couple the light beam emitted by the semiconductor laser chip 1 into the optical fiber assembly 8;

[0145] S7, fixing the coupled optical fiber assembly 8 and the laser housing 6, and the fixing method can be any one of laser welding, energy storage welding, metal solder welding and adhesive curing.

[0146] like Fig.11 As shown, when the central axis of the optical isolator 3 is coaxial with the main optical axis of the semiconductor laser chip 1 but in a rotated angle state, the method for manufacturing a high linearity and low noise semiconductor laser of this embodiment includes the following steps:

[0147] S1, install the optical isolator 3 into the laser housing 6, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0148] S2, using UV glue to pre-fix the optical isolator 3 with the polarization direction adjusted and the laser housing 6;

[0149] S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the light intensity of the semiconductor laser output light;

[0150] S4, judging whether the light intensity index of the semiconductor laser output light is optimal, if it is optimal, executing step S5; if it is not optimal, removing the pre-cured UV ultraviolet glue, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the light intensity index of the semiconductor laser output light is optimal, and then executing step S5;

[0151] S5, keeping the optical isolator 3 at the position where the light intensity index of the semiconductor laser output light is optimal, and testing the linearity of the semiconductor laser output light;

[0152] S6, judging whether the linearity index of the semiconductor laser output light is optimal, if it is optimal, executing step S7; if it is not optimal, removing the pre-cured UV glue, releasing the pre-fixation of the optical isolator 3, coaxially rotating the optical isolator 3, repeating steps S2 and S5, until the linearity index of the semiconductor laser output light is optimal, and then executing step S7;

[0153] S7, completely glue and fix the optical isolator 3 in the laser housing 6;

[0154] S8, insert the optical fiber assembly 8 into the through hole of the light outlet of the laser housing 6, and perform active coupling by adjusting in the X, Y, and Z directions to couple the light beam emitted by the semiconductor laser chip 1 into the optical fiber assembly 8;

[0155] S9, fixing the coupled optical fiber assembly 8 and the laser housing 6, and the fixing method can be any one of laser welding, energy storage welding, metal solder welding and adhesive curing.

[0156] like Fig.12 As shown, when the central axis of the optical isolator 3 is in an inclined off-axis state with respect to the main optical axis of the semiconductor laser chip 1, the method for manufacturing a semiconductor laser with high linearity and low noise in this embodiment includes the following steps:

[0157] S1, install the optical isolator 3 into the laser housing 6, and align the positioning mark on the optical isolator 3 with the positioning mark on the laser body;

[0158] S2, using UV glue to pre-fix the optical isolator 3 with the polarization direction adjusted and the laser housing 6;

[0159] S3, S3, connecting the semiconductor laser with the pre-fixed optical isolator 3 to the active online test system for coupling test, and testing the light intensity of the semiconductor laser output light;

[0160] S4, judging whether the light intensity index of the semiconductor laser output light is optimal, if it is optimal, executing step S5; if it is not optimal, removing the pre-cured UV ultraviolet glue, releasing the pre-fixation of the optical isolator 3, adjusting the position of the optical isolator 3, repeating steps S2 and S3, until the light intensity index of the semiconductor laser output light is optimal, and then executing step S5;

[0161] S5, keeping the optical isolator 3 at the position where the light intensity index of the semiconductor laser output light is optimal, and testing the linearity of the semiconductor laser output light;

[0162] S6, judging whether the linearity index of the semiconductor laser output light is optimal, if it is optimal, executing step S7; if it is not optimal, removing the pre-cured UV glue, releasing the pre-fixation of the optical isolator 3, coaxially rotating the optical isolator 3, repeating steps S2 and S5, until the linearity index of the semiconductor laser output light is optimal, and then executing step S7;

[0163] S7, keeping the optical isolator 3 at a position where the light intensity and linearity of the semiconductor laser output light are optimal, and testing the optical link noise of the semiconductor laser output light;

[0164] S8, judging whether the optical link noise index of the semiconductor laser output light is optimal, if it is optimal, executing step S9; if it is not optimal, removing the pre-cured UV ultraviolet glue, releasing the pre-fixation of the optical isolator 3, tilting and eccentrically adjusting the optical isolator 3, repeating steps S2 and S7, until the optical link noise index of the semiconductor laser output light is optimal, and then executing step S9;

[0165] S9, completely glue and fix the optical isolator 3 in the laser housing 6;

[0166] S10, inserting the optical fiber assembly 8 into the through hole of the light outlet of the laser housing 6, and performing active coupling by adjusting in the X, Y, and Z directions to couple the light beam emitted by the semiconductor laser chip 1 into the optical fiber assembly 8;

[0167] S11, fixing the coupled optical fiber assembly 8 and the laser housing 6, and the fixing method can be any one of laser welding, energy storage welding, metal solder welding and adhesive curing.

[0168] Embodiment 6

[0169] Following the high linearity and low noise semiconductor laser provided in the first, second, third, fourth or fifth embodiment, Fig.13 As shown, the isolator includes a magnetic ring 32 and a Faraday square rotating lens 31, and the magnetic ring 32 is provided with a square inner hole, and the Faraday square rotating lens 31 is fixed in the square inner hole. In this embodiment, the Faraday square rotating lens 31 and the magnetic ring 32 are fixedly connected by gluing and curing. Since the square inner hole on the magnetic ring 32 is consistent with the shape of the Faraday square rotating lens 31, the magnetic ring 32 is sleeved on the outer peripheral surface of the Faraday square rotating lens 31, and the four sides of the Faraday square rotating lens 31 can be glued and fixed to the magnetic ring 32, which can ensure the high reliability of the Faraday square rotating lens 31 after installation and curing.

[0170] Furthermore, the outer peripheral surface of the Faraday square rotating mirror 31 can be completely fitted with the inner wall of the square inner hole of the magnetic ring 32, which can not only ensure the high reliability of the Faraday square rotating mirror 31 after installation and curing, but also ensure the consistency of the polarization direction of the optical isolator 3 body, further improve the stability of the optical isolator 3 in the high-linearity and low-noise semiconductor laser, reduce the optical link noise formed by the reflected light generated by the optical isolator 3, and improve the sensitivity and stability of the laser gas sensor.

[0171] In one embodiment, one side of the square inner hole extends to the outer peripheral surface of the magnetic ring 32. Fig.14 As shown, the square inner hole is connected to the outer peripheral surface of the magnetic ring 32, which is convenient for the installation of the Faraday square rotating mirror 31, and the Faraday square rotating mirror 31 still has three sides that can be glued and fixed to the magnetic ring 32, which can ensure the high reliability of the Faraday square rotating mirror 31 after installation and curing.

[0172] In some embodiments, the metal steel ring 33 is not provided outside the magnetic ring 32 , which can effectively reduce material costs and achieve cost reduction and efficiency improvement without affecting reliability and applicability.

[0173] In some embodiments, the magnetic ring 32 is covered with a metal steel ring 33 to protect the magnetic ring 32 and improve the isolation effect of the optical isolator 3 .

[0174] The Faraday square rotating mirror 31 of this embodiment includes a polarizing plate, a Faraday rotating plate, and a polarizing stop plate; each corner of the square inner hole of the magnetic ring 32 can be provided with a glue groove recessed into the magnetic ring 32 to facilitate glue injection and fixation of the Faraday square rotating mirror 31.

[0175] Although the above-mentioned embodiments 1 to 4 exemplarily illustrate that the optical isolator 3 adopts different installation methods of coaxial, coaxial but rotation angle, and tilted eccentricity, and adopts an active online test installation method to reduce the noise generated by reflected light and stray light in the laser body or in the optical link, and improve the linearity characteristics of the laser output of the laser body, those skilled in the art know that based on the basic technical concept of the present utility model, the above-mentioned method can also be used to install the optical isolator 3 at any position on the optical path of the semiconductor laser, and different fixing methods can be used to achieve the effects of the above three installation methods.

[0176] The above description is only a preferred embodiment of the present invention and is 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 high linearity and low noise semiconductor laser, comprising a laser body, characterized in that: A semiconductor laser chip and an optical isolator are arranged in the laser body, and the central axis of the optical isolator is in a coaxial state, a coaxial state but in a rotation angle state, or a tilted and eccentric state with the main optical axis of the semiconductor laser chip.

2. The high linearity and low noise semiconductor laser as claimed in claim 1, characterized in that: The isolator comprises a magnetic ring and a Faraday square rotating mirror. The magnetic ring is provided with a square inner hole, and the Faraday square rotating mirror is fixed in the square inner hole.

3. The high linearity and low noise semiconductor laser as claimed in claim 2, characterized in that: One side of the square inner hole extends to the outer peripheral surface of the magnetic ring.

4. The high linearity and low noise semiconductor laser as claimed in claim 2, characterized in that: The magnetic ring outer sleeve is provided with a metal steel ring.

5. The high linearity and low noise semiconductor laser according to any one of claims 1 to 4, characterized in that: The semiconductor laser is a coaxial packaged laser. The laser body includes a TO tube seat and a TO tube body. One end of the TO tube body is fixed on the top surface of the TO tube seat. The semiconductor laser chip is arranged on the top surface of the TO tube seat in the TO tube body. The optical isolator is arranged in the light outlet end of the TO tube body.

6. The high linearity and low noise semiconductor laser according to any one of claims 1 to 4, characterized in that: The semiconductor laser is a planar package type laser. The laser body comprises a laser housing. The semiconductor laser chip and the optical isolator are both arranged in the laser housing.

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