A package structure of a tunable laser

Abstract

The utility model discloses a kind of packaging structure of tunable laser, including packaging pedestal (1) and laser chip (2), it is characterized by: still including heat insulating part (3), the heat insulating part (3) is installed between the packaging pedestal (1) and laser chip (2). Compared with prior art, the packaging structure of tunable laser of the utility model can improve current tuning coefficient.

Description

Technical Field

[0001] This utility model relates to the field of laser technology, specifically to a packaging structure for a tunable laser. Background Technology

[0002] A tunable laser is a laser whose output wavelength can be continuously changed within a certain range. Compared with traditional fixed-wavelength lasers, its core advantages lie in wavelength flexibility, wide tuning range (ultraviolet to infrared), and high-precision control, making it a core tool in fields such as optical communication, spectral analysis, and biomedicine.

[0003] Tunable lasers achieve wavelength tuning by changing the characteristics of the resonant cavity or the parameters of the gain medium. The main technologies fall into three categories:

[0004] (1) Current control technology: By changing the magnitude of the injected current, the carrier concentration is changed, the refractive index of the gain medium is adjusted, and wavelength shift is achieved. For details, please refer to Chinese patent "A fast tunable semiconductor laser" with patent application number CN202111580976.7.

[0005] (2) Temperature control technology: By adjusting the temperature through a semiconductor cooler, the refractive index of the material is changed to achieve wavelength shift. For details, please refer to the Chinese patent "Compact and integrable tunable laser packaging structure and its integration method" with patent application number CN202410169017.3.

[0006] (3) Mechanical control technology: The length of the resonant cavity is adjusted by using MEMS micromirrors or movable gratings to achieve ultra-wide tuning.

[0007] Existing tunable laser packaging structures include a packaging substrate, a laser chip, and a heat sink mounted between the packaging substrate and the laser chip. This heat sink is used to transfer heat generated by the laser chip to the packaging substrate for heat dissipation. Typically, the effective refractive index *n* of the laser changes with increasing carrier concentration and temperature. Since the internal resonant wavelength *λ* of the laser satisfies *mλ = nL*, where *m* is an integer, *n* is the refractive index, and *L* is the cavity length, changes in *n* lead to changes in wavelength *λ*. Generally, increased temperature leads to an increase in *n*, resulting in a longer lasing wavelength. The coefficient of variation of the lasing wavelength with temperature is approximately 0.08 nm / ℃. Increasing the current above the laser threshold leads to increased heat generation, resulting in a longer laser wavelength. Under good heat dissipation conditions, the coefficient of variation of the lasing wavelength with current is 0.035 nm / mA; this coefficient is also called the current tuning coefficient.

[0008] The current tuning coefficient is a core parameter for measuring the dynamic performance of tunable lasers. In the future, with the optimization of quantum well materials and the development of silicon photonics hybrid integration technology, high coefficient and low nonlinear current tuning will become the evolution direction of tunable lasers. Utility Model Content

[0009] The technical problem to be solved by this utility model is to provide a packaging structure for a tunable laser that can improve the current tuning coefficient, based on the current state of the technology.

[0010] The technical solution adopted by this utility model to solve the above-mentioned technical problems is: a packaging structure for a tunable laser, including a packaging base and a laser chip, characterized in that: it further includes a heat insulation component, which is installed between the packaging base and the laser chip.

[0011] Preferably, the thermal conductivity of the material used for the insulation component is less than 30 W / mK.

[0012] Furthermore, the insulation component is made of glass.

[0013] Preferably, the encapsulation base is made of Kovar alloy.

[0014] Preferably, the heat insulation component is flat and has a first surface and a second surface opposite to each other. The back side of the laser chip is in close contact with the first surface of the heat insulation component, and the second surface of the heat insulation component is in close contact with the wall of the packaging base.

[0015] Compared with the prior art, the advantages of this utility model are: by replacing the heat sink substrate in the existing packaging structure with an insulating component, the heat of the laser chip can be prevented from spreading, so that all the heat generated by the injected current is used to heat the laser chip, and then the influence of temperature on wavelength is used to increase the current tuning coefficient, thereby achieving a wide range of frequency sweep under a certain current. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an embodiment of the packaging structure of the tunable laser of this utility model;

[0017] Figure 2 This is a schematic diagram of the output beam power variation curve, the monitoring beam power variation curve, and the main beam power variation curve in an embodiment of the control method for the packaging structure of the tunable laser of this utility model.

[0018] Figure 3 This is a graph showing the relationship between the injected current and time in Embodiment 1 of the control method for the packaging structure of the tunable laser of this utility model.

[0019] Figure 4The spectrum of the laser emitted by the laser under different injection currents in Embodiment 1 of the control method for the packaging structure of the tunable laser of this utility model;

[0020] Figure 5 This is a graph showing the relationship between the laser wavelength and the injection current in Embodiment 1 of the control method for the packaging structure of the tunable laser of this utility model.

[0021] Figure 6 This is a graph showing the relationship between the laser current tuning coefficient and the injection current in Embodiment 1 of the control method for the packaging structure of the tunable laser of this utility model.

[0022] Figure 7 The graph shows the relationship between the injected current and time in Embodiment 2 of the control method for the packaging structure of the tunable laser of this utility model.

[0023] Figure 8 This is a graph showing the relationship between the injected current and time in Embodiment 3 of the control method for the packaging structure of the tunable laser of this utility model. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] In the specification and claims of this utility model, terms indicating direction, such as "front," "rear," "upper," "lower," "left," "right," "side," "top," and "bottom," are used to describe various exemplary structural parts and elements of this utility model. However, the use of these terms is merely for the purpose of explanation and is based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in this utility model can be arranged in different orientations, these terms indicating direction are for illustrative purposes only and should not be regarded as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

[0026] like Figure 1 The image shows a preferred embodiment of the packaging structure for the tunable laser of this invention. The packaging structure includes a packaging base 1, a laser chip 2, and a heat insulation component 3.

[0027] The encapsulation base 1 is made of Kovar alloy.

[0028] A heat insulation component 3 is installed between the packaging base 1 and the laser chip 2. The thermal conductivity of the material used for the heat insulation component 3 is less than 30 W / mK, preferably 0.7 to 1.4 W / mK. Specifically, the heat insulation component 3 is flat and has opposing first and second surfaces. The back surface of the laser chip 2 is in close contact with the first surface of the heat insulation component 3, and the second surface of the heat insulation component 3 is in close contact with the wall surface of the packaging base 1. In this embodiment, the heat insulation component 3 is made of glass.

[0029] This utility model also provides a control method for the packaging structure of a tunable laser, which includes the following steps: tuning the lasing wavelength by changing the magnitude of the injection current of the laser chip 2.

[0030] In this invention, by replacing the heat sink substrate in the existing packaging structure with the heat insulation component 3, the heat of the laser chip 2 can be prevented from spreading, so that all the heat generated by the injected current is used to heat the laser chip 2. Then, by utilizing the influence of temperature on wavelength, the current tuning coefficient is increased, and a wide range of frequency sweeps can be achieved under a certain current scan.

[0031] Furthermore, the injected current of laser chip 2 is a pulsed current. In this invention, the pulse width of the pulsed current is less than 100ms, preferably 5-50ms, and the duty cycle of the pulsed current is less than 10%, preferably 0.5-5%. This pulsed operation mode has the following advantages: First, the temperature rise of laser chip 2 within one scanning cycle mainly depends on the size of the laser chip's heat capacity and the heat accumulated within one cycle; Second, in the previous scanning cycle, the temperature of laser chip 2 will decrease when the injected current value is 0, so as to return to the initial temperature, so that the lasing wavelength of the next scanning cycle changes with the current in the same way as the previous cycle; Third, for the same current scanning range, the wavelength scanning range of the laser can be adjusted by adjusting the pulse width or the duty cycle. Generally, the wider the pulse width and the larger the duty cycle, the larger the wavelength scanning range of the laser.

[0032] However, due to poor heat dissipation in the laser, the optical power of the laser decreases, leading to power saturation under high current and resulting in poor linearity. Therefore, in this invention, as... Figure 2 As shown, during the current injection process, the output beam can be divided into the main beam and the monitoring beam. By performing correlation processing on the output beam power change curve a and the monitoring beam power change curve b, the main beam power change line c is obtained, thus achieving linear power growth over a wide current range.

[0033] Example 1:

[0034] The pulse width of the injected current was set to 50ms, the duty cycle of the injected current was set to 4%, and the scanning range of the injected current was set to 20–120mA. The relationship between the injected current and time is shown in the figure below. Figure 3 As shown;

[0035] The spectra of the laser emitted by the laser under different injection currents were tested and are shown below. Figure 4 As shown, according to Figure 4 The parameters in the plot are obtained as follows Figure 5 The graph shown depicts the relationship between the laser's lasing wavelength and the injection current. Next, [the graph will be used to...] Figure 4 Differential calculations can be plotted as follows Figure 6 The graph shows the relationship between the laser current tuning coefficient and the injection current.

[0036] from Figure 5 and Figure 6 It can be seen that within one scan cycle, the injected current scans from 20mA to 120mA, and the wavelength increases from 1532.5nm to 1541.5nm, corresponding to a wavelength scan range of 9nm; the current tuning coefficient is 0.04~0.16nm / mA, with an average value of 0.1nm / mA, indicating that the current tuning coefficient can be increased from the original 0.035nm / mA to 0.1nm / mA.

[0037] Example 2:

[0038] The difference from Example 1 is that the pulse width of the injected current is set to 25ms, and the relationship between the injected current and time is shown in the figure below. Figure 7 As shown;

[0039] Based on testing and calculations, the corresponding wavelength scanning range is 6.4nm.

[0040] Example 3:

[0041] The difference from Example 1 is that the duty cycle of the injected current is set to 2%, and the relationship between the injected current and time is shown in the figure below. Figure 8 As shown;

[0042] According to testing and calculation, the corresponding wavelength scanning range is 5.8nm.

Claims

1. A packaging structure for a tunable laser, comprising a packaging base (1) and a laser chip (2), characterized in that: It also includes a heat insulation component (3), which is installed between the packaging base (1) and the laser chip (2).

2. The packaging structure of the tunable laser according to claim 1, characterized in that: The thermal conductivity of the material used in the insulation component (3) is less than 30 W / mK.

3. The packaging structure of the tunable laser according to claim 2, characterized in that: The insulation component (3) is made of glass.

4. The packaging structure of the tunable laser according to claim 1, characterized in that: The encapsulation base (1) is made of Kovar alloy.

5. The packaging structure of the tunable laser according to any one of claims 1 to 4, characterized in that: The heat insulation component (3) is flat and has a first surface and a second surface opposite to each other. The back side of the laser chip (2) is in close contact with the first surface of the heat insulation component (3), and the second surface of the heat insulation component (3) is in close contact with the wall of the packaging base (1).

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