Non-magnetic VCSEL laser packaging structure integrated with collimating lens

Abstract

The invention discloses a non-magnetic VCSEL laser packaging structure integrated with a collimating lens. The non-magnetic VCSEL laser packaging structure comprises a frame, a temperature control unit and a VCSEL chip, the frame comprises an oxygen-free copper frame and an aluminum nitride substrate, the collimating lens is integrated on the oxygen-free copper frame and is located right above the VCSEL chip so as to collimate laser beams, and the aluminum nitride substrate is connected with the temperature control unit up and down; the temperature control unit comprises an NTC thermistor, an upper layer 2N polar distance heating coil and a lower layer 2N polar distance heating coil which are respectively connected with electrodes to an external circuit. The NTC thermistor is close to the VCSEL chip and located in the middle of the upper layer 2N polar distance heating coil, real-time temperature is collected, the heating coil is controlled through an external control circuit, and therefore the temperature of the VCSEL chip is adjusted. According to the invention, the low-frequency magnetic field interference caused by packaging and heating is reduced, the magnetic field of the packaged VCSEL laser at the distance of 4 cm is 2.54 nT, which is far smaller than that of the common TO packaging, and the non-magnetic laser packaging integrated with the collimating lens is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor laser packaging, and in particular relates to a non-magnetic VCSEL laser packaging structure with an integrated collimating lens. Background Art

[0002] VCSEL (Vertical Cavity Surface Emitting Laser) laser is a key component for miniaturizing atomic magnetometers. Atomic magnetometers can measure extremely weak magnetic fields and can be widely used in geology, medicine, and military fields. In order to improve the measurement sensitivity of atomic magnetometers, laser pumping is usually used. VCSEL lasers can work stably in high temperature environments, have the characteristics of small temperature drift of the lasing wavelength, low operating threshold, and miniaturized packaging. They are key components for miniaturizing atomic magnetometers. However, atomic magnetometers are extremely sensitive to magnetic field signals, so VCSEL lasers with non-magnetic packaging are required.

[0003] At present, the commonly used package for VCSEL lasers is TO (transistor outline) package, which is mainly composed of glass lens, kovar alloy shell, VCSEL chip, TEC (thermoelectric cooler) and copper substrate. There are two problems with this structure: First, the kovar alloy shell has strong magnetism, which will reduce the response signal strength of the magnetometer and is not conducive to improving the sensitivity of the magnetometer. Using TEC to control its current for heating or cooling, this DC heating method will produce a large low-frequency magnetic field, affecting the measurement results and sensitivity of the atomic magnetometer. After measurement, the magnetic field of the TO-packaged VCSEL laser at 4 cm is still 40.83nT, which seriously affects the measurement results of the atomic magnetometer. Second, the divergence angle of VCSEL itself is large, and a collimating lens is required to improve the pumping effect of the magnetometer. The existing package uses ordinary glass lenses, which need to be collimated again, which is not conducive to the miniaturization of the atomic magnetometer. In order to achieve a collimating effect without the influence of additional magnetic fields, it is necessary to design a non-magnetic VCSEL laser packaging structure with an integrated collimating lens Summary of the invention

[0004] The purpose of the present invention is to design a non-magnetic VCSEL laser packaging structure with an integrated collimating lens. The device uses non-magnetic oxygen-free copper and aluminum nitride materials to eliminate the influence of the shell material on the magnetic field. The laser heating device uses a double-layer heating coil instead of TEC to reduce the magnetic field caused by heating. A collimating lens is integrated at the laser outlet position to improve the pumping effect of the atomic magnetometer. Finally, it is measured that the magnetic field of the packaged VCSEL laser at a distance of 4 cm is 2.54nT, which is much smaller than the 40.83nT of the magnetic field of the ordinary TO package, which greatly reduces the influence of the laser magnetic field on the atomic magnetometer.

[0005] The technical solution of the present invention is as follows:

[0006] A non-magnetic VCSEL laser packaging structure with an integrated collimating lens, characterized in that it comprises a frame, the frame has a cavity surrounded by side walls, the frame is made of oxygen-free copper material, an aluminum nitride substrate is arranged in the cavity, and an upper layer 2 is arranged on the upper surface of the aluminum nitride substrate N The pole pitch heating coil, N is a positive integer, and the lower surface of the aluminum nitride substrate is provided with a lower layer 2 N Pole pitch heating coil, the upper layer 2 N The center of the inter-pole heating coil is provided with a VCSEL chip, an NTC thermistor and an upper center electrode. N The upper edge electrodes are distributed on the edge of the inter-pole heating coil, and a collimating lens is arranged directly above the VCSEL chip. The collimating lens is integrated on the frame. N The lower edge electrodes are distributed on the edges of the inter-pole heating coil.

[0007] The VCSEL chips are connected to the upper and lower layers 2 N The inter-pole heating coil, NTC thermistor and collimating lens, the upper and lower layers 2 N The inter-pole heating coil and the NTC thermistor are both connected to an external control circuit for setting the temperature, and the collimating lens is connected to the atomic gas chamber.

[0008] The external control circuit controls the upper and lower layers 2 by PID control N The polar heating coil stabilizes the temperature near the VCSEL chip to an optimal temperature, the NTC thermistor feeds back the temperature measured from the VCSEL chip to the external control circuit, and the collimating lens pumps the laser from the VCSEL chip into the atomic gas chamber.

[0009] The packaged VCSEL laser has a magnetic field of 2.54nT at a distance of 4cm.

[0010] The collimating lens is an aspherical lens.

[0011] The electrode is made of pure copper and the surface is gold-plated.

[0012] The technical effects of the present invention are as follows: the present invention provides a non-magnetic VCSEL laser packaging structure with an integrated collimating lens. After measurement, the magnetic field of the packaged VCSEL laser at a distance of 4 cm is 2.54nT, which is much smaller than the magnetic field of the ordinary TO package, thereby realizing a non-magnetic laser packaging with an integrated collimating lens.

[0013] The advantages of the present invention compared with the prior art are:

[0014] (1) The present invention adopts non-magnetic structural materials, including oxygen-free copper and aluminum nitride. Compared with the kovar alloy shell (kovar alloy is kovar alloy) adopted in the existing TO package (i.e. transistor wheel package), the magnetism is greatly reduced, thereby improving the measurement sensitivity of the miniaturized atomic magnetometer.

[0015] (2) The present invention adopts 2 N The inter-pole heating coil replaces the existing packaged TEC (thermoelectric cooler) to heat the VCSEL chip, and the specially configured coil reduces the interference of the magnetic field.

[0016] (3) The present invention takes into account the need for miniaturization of the atomic magnetometer and integrates a collimating lens into the laser frame. The required light beam is obtained after the laser is emitted, thereby improving the pumping effect of the atomic magnetometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a schematic structural diagram of a non-magnetic VCSEL laser packaging structure with an integrated collimating lens.

[0018] Figure 2 The present invention is a schematic diagram of the working principle of a non-magnetic VCSEL laser packaging structure with an integrated collimating lens. Figure 2 Including connecting the upper and lower layers 2 N The VCSEL chip (VCSEL, vertical cavity surface emitting laser) of the polar distance heating coil (N is a positive integer), NTC negative feedback thermistor (NTC-Negative Temperature Coefficient thermistor, negative temperature coefficient thermistor) and collimating lens, the upper and lower layers 2 N The inter-polar heating coil and the NTC thermistor 4 are both connected to an external control circuit for setting the temperature, and the collimating lens 1 is connected to the atomic gas chamber. The external control circuit controls the upper and lower layers 2 by PID control. N The polar heating coil stabilizes the temperature near the VCSEL chip to the optimal temperature (PID, proportional integral differential control algorithm). The NTC negative feedback thermistor feeds back the temperature measured from the VCSEL chip to the external control circuit. The collimating lens pumps the laser from the VCSEL chip to the atomic gas chamber.

[0019] The reference numerals are as follows: 1 is a collimating lens; 2 is an oxygen-free copper frame; 3 is a VCSEL chip (VCSEL, vertical cavity surface emitting laser); 4 is an NTC thermistor (NTC-Negative Temperature Coefficient thermistor); 5 is an upper edge electrode; 6 is an upper 2 NThe inter-pole heating coil (N is a positive integer); 7 is the upper center electrode; 8 is the aluminum nitride substrate; 9 is the lower edge electrode; 10 is the lower 2 N Pole pitch heating coil. DETAILED DESCRIPTION

[0020] Below is the attached figure ( Figure 1-Figure 2 ) and Examples illustrate the present invention.

[0021] Figure 1 The present invention is a schematic structural diagram of a non-magnetic VCSEL laser packaging structure with an integrated collimating lens. Figure 2 This is a schematic diagram of the working principle of a non-magnetic VCSEL laser packaging structure with an integrated collimating lens according to the present invention. Figure 1 to Figure 2 As shown, a non-magnetic VCSEL laser packaging structure with an integrated collimating lens includes a frame (i.e., an oxygen-free copper frame 2), wherein the frame has a cavity surrounded by side walls, wherein the frame is made of an oxygen-free copper material, wherein an aluminum nitride substrate 8 is disposed in the cavity, wherein an upper layer 2 is disposed on the upper surface of the aluminum nitride substrate 8. N The inter-pole heating coil 6, N is a positive integer, and the lower surface of the aluminum nitride substrate 8 is provided with a lower layer 2 N The pole pitch heating coil 10, the upper layer 2 N The center of the inter-pole heating coil 6 is provided with a VCSEL chip 3, an NTC thermistor 4 and an upper center electrode 7. N The upper edge electrode 5 is distributed on the edge of the inter-pole heating coil 6. A collimating lens 1 is arranged directly above the VCSEL chip 3. The collimating lens 1 is integrated on the frame. N The lower edge electrodes 9 are distributed on the edges of the inter-pole heating coil 10 .

[0022] The VCSEL chip 3 is connected to the upper and lower layers 2 respectively. N Pole spacing heating coil (i.e. upper 2 N Pole spacing heating coil 6 and lower layer 2 N The pole-distance heating coil 10), NTC negative feedback thermistor and collimating lens, the upper and lower layers 2 N The inter-pole heating coil and the NTC negative feedback thermistor are both connected to an external control circuit for setting the temperature, and the collimating lens is connected to the atomic gas chamber. The external control circuit controls the upper and lower layers 2 by PID control. N Pole spacing heating coil (i.e. upper 2 N Pole spacing heating coil 6 and lower layer 2 NThe polar heating coil 10 is used to stabilize the temperature near the VCSEL chip 3 to the optimal temperature, the NTC thermistor 4 feeds back the temperature measured from the VCSEL chip 3 to the external control circuit, and the collimating lens 1 pumps the laser from the VCSEL chip 3 to the atomic gas chamber.

[0023] The magnetic field of the packaged VCSEL laser at a distance of 4 cm is 2.54 nT. The collimating lens 1 is an aspherical lens. The electrodes (including the upper edge electrode 5, the upper center electrode 7, and the lower edge electrode 9) are made of pure copper with gold plating on the surface.

[0024] The present invention discloses a non-magnetic VCSEL laser packaging structure with an integrated collimating lens. The device comprises a frame, a temperature control unit and a VCSEL chip. The frame comprises an oxygen-free copper frame and an aluminum nitride substrate. The collimating lens is integrated on the oxygen-free copper frame and is located directly above the VCSEL chip so as to collimate the laser beam. The aluminum nitride substrate is connected to the temperature control unit from top to bottom. The temperature control unit comprises an NTC thermistor, an upper layer 2 N Pole spacing heating coil and lower layer 2 N The inter-electrode heating coils are connected to the external circuits with the electrodes. The NTC thermistor is close to the VCSEL chip and is located on the upper layer. N The pole is in the middle of the heating coil, real-time temperature is collected, and the heating coil is controlled by an external control circuit to adjust the temperature of the VCSEL chip. N The polar heating coil heats the VCSEL chip, reducing the low-frequency magnetic field interference caused by packaging and heating. Secondly, a collimating lens is integrated to shape the laser beam. The final measurement shows that the magnetic field of the packaged VCSEL laser at a distance of 4 cm is 2.54nT, which is much smaller than the magnetic field of the ordinary TO package, realizing a non-magnetic laser package with an integrated collimating lens.

[0025] like Figure 1 As shown: The present invention is a non-magnetic VCSEL laser packaging structure with an integrated collimating lens, comprising a frame, a temperature control unit and a VCSEL chip; the frame comprises an oxygen-free copper frame (2) and an aluminum nitride substrate (8); the collimating lens (1) is integrated on the oxygen-free copper frame (2) and is located directly above the VCSEL chip so as to collimate the laser beam; the aluminum nitride substrate (8) is connected to the temperature control unit from top to bottom; the temperature control unit comprises an NTC thermistor (4), an upper layer 2 N The inter-pole heating coil (6) and the lower layer 2 N The inter-pole heating coil (10) is connected to the external circuit with the electrodes (5), (7), (9) respectively. The NTC thermistor (4) and the VCSEL chip (3) are close to and located on the upper layer 2.N The pole is in the middle of the heating coil (6), real-time temperature is collected, and the heating coil is controlled by an external control circuit, thereby adjusting the temperature of the VCSEL chip (3) to the optimal working temperature. The operation steps of the above parts are as follows:

[0026] Step 1: The external circuit sets the required temperature of the VCSEL chip (3) and controls the upper and lower N The inter-pole heating coil (6) (10) starts heating.

[0027] Step 2, feeding back to the external control circuit through the NTC thermistor (4), using the PID algorithm to control, so that the temperature near the VCSEL chip (3) is stabilized to the optimal temperature.

[0028] Step 3: When the laser reaches the optimal wavelength, the light beam is collimated by a collimating lens (1) installed on the frame to finally obtain the desired light beam.

[0029] In terms of material selection, the non-magnetic packaged VCSEL laser packaging structure for miniaturized atomic magnetometers takes into account smaller magnetic field interference and improved sensitivity of the atomic magnetometer. It uses oxygen-free copper and aluminum nitride as the frame structure and non-magnetic glue for assembly to ensure overall low magnetism.

[0030] The non-magnetic package VCSEL laser packaging structure for miniaturized atomic magnetometers adopts 2 N The polar heating coil replaces the existing TEC to heat the laser chip, which solves the low-frequency magnetic field problem of DC heating and further improves the sensitivity of the atomic magnetometer.

[0031] The non-magnetic packaged VCSEL laser packaging structure for miniaturized atomic magnetometers integrates a collimating lens, so that the laser light is shaped when it is emitted, without the need to further add optical elements to the atomic magnetometer, further reducing the volume of the atomic magnetometer and improving the pumping effect of the atomic magnetometer.

[0032] like Figure 2 As shown: First, the external circuit sets the required temperature of the VCSEL chip (3) and controls the upper and lower N The inter-pole heating coil (6) (10) starts heating, and the NTC thermistor (4) is used to feed back to the external control circuit, and the PID algorithm is used to stabilize the temperature near the VCSEL chip (3) to the optimal temperature. At this time, the laser reaches the optimal wavelength, and the collimating lens (1) installed on the frame is used to collimate the beam, and finally the desired beam is obtained.

[0033] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. It is pointed out here that the above description helps those skilled in the art to understand the invention, but does not limit the protection scope of the invention. Any equivalent replacement, modification and / or simplification of the above description without departing from the essence of the invention falls within the protection scope of the invention.

Claims

1. A non-magnetic VCSEL laser packaging structure with integrated collimating lens, characterized in that: The frame comprises a cavity surrounded by side walls, the frame is made of oxygen-free copper material, an aluminum nitride substrate is arranged in the cavity, and an upper layer 2 is arranged on the upper surface of the aluminum nitride substrate N The pole pitch heating coil, N is a positive integer, and the lower surface of the aluminum nitride substrate is provided with a lower layer 2 N Pole pitch heating coil, the upper layer 2 N The center of the inter-pole heating coil is provided with a VCSEL chip, an NTC thermistor and an upper center electrode. N The upper edge electrodes are distributed on the edge of the inter-pole heating coil, and a collimating lens is arranged directly above the VCSEL chip. The collimating lens is integrated on the frame. N The lower edge electrodes are distributed on the edges of the inter-pole heating coil.

2. The non-magnetic VCSEL laser packaging structure with integrated collimating lens according to claim 1, characterized in that: The VCSEL chips are connected to the upper and lower layers 2 N The inter-pole heating coil, NTC thermistor and collimating lens, the upper and lower layers 2 N The inter-pole heating coil and the NTC thermistor are both connected to an external control circuit for setting the temperature, and the collimating lens is connected to the atomic gas chamber.

3. The non-magnetic VCSEL laser packaging structure with integrated collimating lens according to claim 2, characterized in that: The external control circuit controls the upper and lower layers 2 by PID control N The polar heating coil stabilizes the temperature near the VCSEL chip to an optimal temperature, the NTC thermistor feeds back the temperature measured from the VCSEL chip to the external control circuit, and the collimating lens pumps the laser from the VCSEL chip into the atomic gas chamber.

4. The non-magnetic VCSEL laser packaging structure with integrated collimating lens according to claim 1, characterized in that: The packaged VCSEL laser has a magnetic field of 2.54nT at a distance of 4cm.

5. The non-magnetic VCSEL laser packaging structure with integrated collimating lens according to claim 1, characterized in that: The collimating lens is an aspherical lens.

6. The non-magnetic VCSEL laser packaging structure with integrated collimating lens according to claim 1, characterized in that: The electrode is made of pure copper and the surface is gold-plated.

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