Optical power monitoring unit and optical power monitoring device for ultra-high temperature aging test

Abstract

The present invention provides an optical power monitoring unit and an optical power monitoring device for ultra-high temperature aging testing, wherein the optical power detection unit includes a heating metal block, a semiconductor light-emitting chip, a collimator and a photoelectric sensor; the semiconductor light-emitting chip is placed above the heating metal block and can emit divergent light when powered on, the collimator is arranged in the transmission path of the divergent light, and the divergent light is converted into a collimated or nearly collimated light beam, the photoelectric sensor receives the collimated light beam after a certain stroke, and detects the optical power of the monitored semiconductor light-emitting chip. One or more reflectors may be provided in the transmission path of the collimated light beam to change the transmission path of the light. By adopting a collimator, the divergent light is converted into a collimated or nearly collimated light beam, so that the laser reaches the photodiode after a certain stroke, and the heat radiation of the heating metal block to the photodiode is weakened, so that the photodiode supports ultra-high temperature aging monitoring, and at the same time effectively improves the service life of the photodiode.

Description

Technical Field

[0001] The present invention relates to the field of aging test, and in particular to an optical power monitoring unit and an optical power monitoring device for ultra-high temperature aging test. Background Art

[0002] All semiconductor components require a certain degree of aging to screen out bad chips, thereby screening out failed or value-changing components to ensure that the products shipped can stand the test of time. Aging tests for laser or LED devices usually require monitoring of optical power. In order to understand the yield of the chip, it is usually necessary to monitor the wavelength performance. Monitoring of spectral performance has additional value for failure analysis. Most of the aging equipment currently available on the market provides voltage / current supply and measurement capabilities, and some of them provide optical power voltage / current test capabilities (LIV or sometimes called PIV).

[0003] According to the form of the product, the temperature of high-temperature aging is usually divided into three orders of magnitude: 85 degrees (device level), 125 degrees (chip operation level) and 175 degrees (chip storage level). However, the maximum operating temperature of general photodiodes is only about 80 degrees, which cannot adapt to ultra-high temperatures, that is, temperatures above 85 degrees. And because the light divergence angle of the laser diode (LD) is usually greater than the numerical aperture (NA) of 0.2, the monitoring PD must be placed near the high-temperature aging block to better capture the light beam, and it also helps to reduce light scattering from adjacent LDs. However, the radiation introduces a local temperature increase that is sufficient to affect the reliability of the monitoring PD, greatly reducing the service life of the monitoring PD. Summary of the invention

[0004] The technical problem solved by the present invention is to provide an optical power monitoring unit and an optical power monitoring device for ultra-high temperature aging test, so as to solve the problem that the photodiode does not support ultra-high temperature aging monitoring and has a short service life.

[0005] The technical solution provided by the present invention to solve the above technical problems is:

[0006] An optical power monitoring unit for ultra-high temperature aging test comprises a heating metal block, a semiconductor light-emitting chip, a collimator and a photoelectric sensor; the semiconductor light-emitting chip is arranged above the heating metal block and can emit divergent light when powered on; the collimator is arranged in the transmission path of the divergent light to convert the divergent light into a collimated or nearly collimated light beam; the photoelectric sensor receives the collimated light beam after a certain stroke and detects the optical power of the monitored semiconductor light-emitting chip.

[0007] According to the above scheme, one or more reflectors may be arranged in the transmission path of the collimated light beam, and the collimated light beam reflected by the reflectors is transmitted to the photodiode.

[0008] According to the above scheme, the collimator is a collimating lens, and the photoelectric sensor is a photodiode.

[0009] According to the above scheme, a movable optical element insertion plate is provided in the transmission path of the collimated light beam, and at least one element hole is provided on the optical element insertion plate, and a light attenuator, a linear transmittance filter or a linear polarizer is provided in the element hole. A through hole may also be provided on the optical element insertion plate, and the collimated light beam is incident on the photoelectric sensor through the through hole. The through hole may also be a through hole formed by not placing an element in the element hole.

[0010] According to the above scheme, it also includes an optical element moving structure, which includes a linear actuator, and the linear actuator drives the optical element insertion plate to move linearly. It can be aligned manually or automatically by the device:

[0011] The optical element moving structure also includes a position sensor, which performs closed-loop feedback according to the real-time position to control the collimated light beam to align with the optical attenuator, linear transmittance filter or linear polarizer on the optical element insertion board.

[0012] To facilitate industrial testing, the present invention also provides an optical power monitoring device for ultra-high temperature aging testing, which includes optical power monitoring units arranged in an array, and the optical power monitoring units are optical power monitoring units with at least one reflector or without a reflector.

[0013] According to the above scheme, the optical power monitoring device also includes an optical element insertion plate and an optical element moving structure, the optical element moving structure includes a linear actuator and a position sensor, the optical element insertion plate is arranged in the transmission path of the collimated light beam, and the optical element insertion plate is arrayed with element hole groups corresponding to the optical power monitoring unit, each element hole group includes at least one through hole and one element hole, and an optical attenuator, a linear transmittance filter or a linear polarizer is installed in the element hole, the linear actuator drives the optical element insertion plate to move relative to each other in a push or pull manner, and the position sensor performs closed-loop feedback according to the real-time position to control the collimated light beam to align with the through hole or element hole on the optical element insertion plate as required.

[0014] The beneficial effects of the present invention are as follows: the optical power monitoring unit of the present invention uses a collimator to convert the divergent light into a collimated light beam, which can be transmitted over a longer distance, thereby expanding the distance from the semiconductor light-emitting chip to the photodiode, so that the laser reaches the photodiode after a certain distance, which is conducive to reducing the heat radiation of the heated metal block to the photodiode, thereby reducing the temperature rise of the photodiode, allowing the photodiode to support ultra-high temperature aging monitoring, and effectively improving the service life of the photodiode. The optical power monitoring units are arranged in an array, and multiple semiconductor light-emitting chips can be measured at the same time, which is time-saving and efficient.

[0015] Furthermore, by setting one or more reflectors, the transmission path of the light beam can be changed. The light beam transmission path can be straight, or it can be bent 90 degrees, or even multi-path bent. Among them, the straight transmission path can reduce the number of reflectors used. Under space constraints, a bending structure, such as 90 degrees, is usually used to further reduce the thermal radiation from the heater block to the photoelectric sensor, thereby minimizing the temperature increase caused by thermal radiation and ensuring the stability of the wavelength and power monitoring device of the semiconductor light-emitting chip in the ultra-high temperature aging test.

[0016] Different optical elements can be inserted into the optical path through the optical element insertion plate to measure different aging parameters: by controlling the collimated light beam to pass through the optical attenuator, the maximum detectable power can be expanded while preventing the optical power from exceeding the maximum measurement power of the photodiode and causing mismeasurement; by controlling the collimated light beam to pass through the linear transmittance filter, the wavelength can be measured; by controlling the collimated light beam to pass through the linear polarizer, the polarization rotation aging characteristics can be measured. To facilitate measurement, through holes can be set on the optical element insertion plate so that the insertion plate does not need to be completely removed to measure the optical power that does not pass through the optical element. At the same time, an optical element moving structure can be introduced to control the collimated light beam to align with the optical attenuator, linear transmittance filter or linear polarizer on the optical element insertion plate according to measurement requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of an optical power monitoring unit according to the first embodiment of the present invention;

[0018] Figure 2 It is a structural schematic diagram of an optical power monitoring unit provided with a reflector and an optical element insertion plate according to a second embodiment of the present invention;

[0019] Figure 3 is a schematic diagram of an optical element moving structure according to a third embodiment of the present invention;

[0020] Figure 4 is a transmittance-wavelength curve of the linear transmittance filter of the present invention;

[0021] Figure 5 Schematic diagram of an optical power monitoring device according to a fourth embodiment of the present invention.

[0022] In the figure: 1 - photodiode (PD), 2 - collimated light beam, 3 - semiconductor light emitting chip, 4 - collimating lens, 5 - heating metal block, 6 - optical element insertion plate, 7 - linear actuator, 8 - position sensor, 9 - element hole, 10 - reflector. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with specific embodiments and drawings.

[0024] Embodiment 1 of the present invention discloses a specific structure of an optical power monitoring unit for ultra-high temperature aging test, such as Figure 1 As shown, it includes a photodiode 1, a semiconductor light-emitting chip 3, a collimating lens 4, and a heater metal block 5. Among them, the photodiode 1 is a semiconductor device composed of a PN junction, has a unidirectional conductive property, can convert optical signals into electrical signals, and can also use a photoelectric sensor, so the optical power of the semiconductor light-emitting chip 3 can be measured. The heater metal block 5 uses a heating device to heat the metal block according to different needs to meet the temperature required for aging of the semiconductor light-emitting chip. The semiconductor light-emitting chip 3, such as a laser diode, is located near the heating metal block 5 and can emit light when powered on. The laser will also have a certain divergence angle, so the divergent light in this article includes laser. The collimating lens 4 is an optical element made of a transparent material (such as glass, crystal, etc.), which is arranged in the transmission path of the light emitted by the semiconductor light-emitting chip 3 to convert the divergent light into a collimated light beam. Other light collimating devices can also be used.

[0025] By using different lenses or other optical elements to convert the divergent light into a collimated light beam, the distance from the semiconductor light-emitting chip to the photodiode can be expanded, so that the light reaches the photodiode 1 after a certain distance, reducing the heat radiation of the heated metal block 5 to the photodiode 1; at the same time, other optical elements such as attenuator filters and linear transmittance filters can be inserted into the test system to better screen out failed chips. For laser diodes, due to the limitations of the acceptable light power density per unit area of ​​the photodiode 1 and the requirements of the lens model for the laser divergence angle, a collimating lens with a micro-focusing function is required to convert the laser light beam into collimated light; at the same time, it can also ensure that other optical elements in the optical path, such as linear filters, attenuators, etc., will not be damaged. In addition, the transmitted light beam is mainly a collimated light beam, or a collimated light beam with light focusing, so that the spot diameter difference on the lens can be matched, so as to achieve a perfect match between the numerical aperture of the laser diode and the focal length of the lens and the light receiving area of ​​the photodiode in a practical sense.

[0026] Embodiment 2 of the present invention discloses an optical power monitoring unit provided with a reflector. Figure 2 As shown, a reflector 10 is provided in the transmission path of the collimated light beam 2, thereby changing the transmission path of the light beam 2. One or more reflectors 10 may also be provided in the transmission path of the collimated light beam 2 as required. The light beam transmission may be straight, or may be bent 90 degrees, or may be bent in multiple paths. Under space constraints, a bending structure is usually used, such as Figure 2 As shown in FIG. 1 , a beam transmission with a bent structure, such as 90 degrees, can further reduce the heat radiation from the heater to the PD.

[0027] In order to better screen out failed chips, various optical filters are needed. Figure 2 As shown, a movable optical element insertion plate 6 can be arranged in the transmission path of the collimated light beam, and an element hole 9 is arranged on the optical element insertion plate 6. An optical element such as an optical attenuator, a linear transmittance filter or a linear polarizer can be arranged in the element hole 9. A through hole can also be arranged on the optical element insertion plate, so that when the optical element is not needed, there is no need to remove the optical element insertion plate 6. The through hole can also be formed by the element hole 9 without an optical element.

[0028] The functions of the optical elements arranged on the optical element insertion plate are as follows:

[0029] The optical power of the semiconductor light-emitting chip can be directly detected through the through hole.

[0030] Optical attenuators are inserted to increase optical power detection to 1W or more using typical 15-25dB attenuators by inserting optical attenuation filters to measure high powers above the maximum current conversion range of the photodiode. Optical attenuators are often inserted to amplify the maximum detectable power while reducing false detections caused by optical saturation.

[0031] The wavelength can be measured by a linear transmittance filter. By inserting a linear transmittance filter to measure the optical power, when the laser emits a single mode at a single wavelength, the relative power ratio with and without the filter can be used to determine the wavelength of the light. Linear transmittance filters can also be used for multi-mode with a pair of wavelengths. Figure 5 As shown in the figure, the transmittance of the linear transmittance filter (LTF) varies linearly with the wavelength in a specific wavelength range. The transmittance of the linear transmittance filter (LTF) varies linearly with the wavelength in a specific wavelength range. It is used for wavelength identification. The transmittance of the LTF must be monotonic to ensure that there is a one-to-one correspondence between the transmittance of the filter and the given wavelength. Mathematically, the filter function can be described as a linear or second-order polynomial equation. In practical applications, using computer-aided function calibration, the transfer function in the figure can usually be segmented and truncated into several linear function ranges and linear interpolation.

[0032] Based on the linear function, the wavelength of light corresponds to the transmittance one by one, and the wavelength detection is achieved through the ratio of the optical power readings, which conforms to the following equation:

[0033]

[0034] Where Trans is the transmittance of light, I0 is the optical power before passing through the linear transmittance filter, and I filter is the optical power after passing through the linear transmittance filter, and λ is the wavelength of the light.

[0035] Optical wavelength extraction is not limited to linear formats. As long as the transmitted optical power dependence is monotonic, fitting functions such as polynomial, sine, exponential, etc. can be used, or it can be truncated to multi-segment linear interpolation.

[0036] If the incident light has multiple wavelengths and multiple modes, the transmitted power is the sum of the transmitted powers at multiple transmittances.

[0037] The polarization rotation aging characteristics of semiconductor light-emitting chips are measured using a linear polarizer.

[0038] Embodiment 3 of the present invention discloses an optical power detection unit with an optical element moving structure. In order to allow the collimated light beam to accurately pass through the set through hole and optical element, an automatic motion system is usually introduced to move the optical element insertion structure. Figure 3 As shown, the structure includes a linear actuator 7 and a position sensor 8, and the optical element insertion plate 6 is connected to the linear actuator 7 and the position sensor 8. The linear actuator 7 drives the optical element insertion plate 6 to move relative to each other in a push or pull manner, and the position sensor 8 performs closed-loop feedback according to the real-time position, thereby accurately controlling the collimated light beam to pass through the through hole, the optical attenuator, the linear transmittance filter or the linear polarizer according to the measurement requirements, so that the photodiode 1 can detect different optical properties.

[0039] The optical power detection device of the embodiment of the present invention comprises a plurality of optical power detection units arranged in an array. The optical power detection units are the optical power detection units in the above embodiment and will not be described in detail here.

[0040] like Figure 5 As shown, in the fourth embodiment of the present invention, the optical power detection device is composed of an array of optical power monitoring units for ultra-high temperature aging test provided with a reflector, which is suitable for industrial mass testing. In order to save resources, only one whole heating metal block can be used. In order to facilitate taking out and use, the device can also be set in the form of a drawer, with a row of chip detection units on each side of the drawer, and multiple drawers are placed in a high temperature aging box for aging test at the same time.

[0041] The optical power monitoring device may also include an optical element insertion plate 6 and an optical element moving structure, the optical element moving structure includes a linear actuator 7 and a position sensor 8, the optical element insertion plate 6 is arranged in the transmission path of the collimated light beam 2, and the optical element insertion plate 6 is arrayed with element hole groups corresponding to the optical power monitoring unit, each element hole group includes at least one through hole and one element hole 9, and optical elements such as an optical attenuator, a linear transmittance filter or a linear polarizer are installed in the element hole 9. The linear actuator 7 drives the optical element insertion plate 6 to move relative to each other in a push or pull manner, and the position sensor 8 performs closed-loop feedback according to the real-time position to control the collimated light beam 2 to align with the through hole or element hole 9 on the optical element insertion plate 6 as required.

[0042] In addition, there are two main ways to arrange the component hole groups: the first arrangement is that the through holes and optical elements are arranged in a horizontal row in a certain order, and then the horizontal rows are repeated horizontally to form a long row; in this way, the distance between adjacent semiconductor light-emitting chips must be greater than or equal to the length of the horizontal row. The second arrangement is that the through holes and optical elements are arranged in a horizontal row in a certain order, and then the horizontal rows are repeated vertically. In this way, the linear actuator can move the optical insertion plate to allow many collimated light beams to pass through the through holes or a specific optical element at the same time according to the test requirements.

[0043] The present invention is suitable for the aging of FP, DFB / DML, and EML laser chips, especially large-scale produced optical chips, including semiconductor laser chips for communication, such as FP type, DFB type, and EML type, photodetector chips, such as PD and APD, optical waveguide chips, such as PLCS, etc., and VCSEL laser high-power LD aging test.

[0044] The above embodiments and principles are only used to illustrate the design ideas and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, any simple modification, equivalent changes and modifications made according to the technical essence of the present invention are within the scope of the technical solution of the present invention.

Claims

1. An optical power monitoring unit for ultra-high temperature aging test, characterized in that: It includes a heating metal block, a semiconductor light-emitting chip, a collimator and a photoelectric sensor; the semiconductor light-emitting chip is arranged above the heating metal block and can emit divergent light when powered on; the collimator is arranged in the transmission path of the divergent light to convert the divergent light into a collimated or nearly collimated light beam; the photoelectric sensor receives the collimated light beam after a certain stroke and detects the optical power of the monitored semiconductor light-emitting chip; a movable optical element insertion plate is provided in the transmission path of the collimated light beam, at least one element hole is provided on the optical element insertion plate, and an optical attenuator, a linear transmittance filter or a linear polarizer is provided in the element hole; one or more reflectors are provided in the transmission path of the collimated or nearly collimated light beam, and the collimated light beam reflected by the reflector is transmitted to the photoelectric sensor.

2. The optical power monitoring unit for ultra-high temperature aging test according to claim 1, characterized in that: The collimator is a collimating or near-collimating lens.

3. The optical power monitoring unit for ultra-high temperature aging test according to claim 1, characterized in that: The photoelectric sensor is a photodiode.

4. The optical power monitoring unit for ultra-high temperature aging test according to claim 1, characterized in that: The optical element insertion plate is also provided with a through hole, through which the collimated light beam is incident on the photoelectric sensor.

5. The optical power monitoring unit for ultra-high temperature aging test according to claim 1, characterized in that: It also includes an optical element moving structure, which includes a linear actuator, and the linear actuator drives the optical element insertion plate to move linearly.

6. The optical power monitoring unit for ultra-high temperature aging test according to claim 5, characterized in that: The optical element moving structure also includes a position sensor, which performs closed-loop feedback according to the real-time position to control the collimated light beam to align with the optical attenuator, linear transmittance filter or linear polarizer on the optical element insertion board.

7. An optical power monitoring device for ultra-high temperature aging test, characterized in that: It comprises optical power monitoring units arranged in an array, and the optical power monitoring units are the optical power monitoring units according to claim 1 or 2.

8. The optical power monitoring device for ultra-high temperature aging test according to claim 7, characterized in that: The optical power monitoring device also includes an optical element insertion plate and an optical element moving structure, wherein the optical element moving structure includes a linear actuator and a position sensor, wherein the optical element insertion plate is arranged in a transmission path of a collimated light beam, and an array of element hole groups corresponding to the optical power monitoring unit are arranged on the optical element insertion plate, wherein each element hole group includes at least one through hole and one element hole, and an optical attenuator, a linear transmittance filter or a linear polarizer is installed in the element hole, wherein the linear actuator drives the optical element insertion plate to move relative to the optical element insertion plate in a push or pull manner, and the position sensor performs closed-loop feedback according to the real-time position, thereby controlling the collimated light beam to align with the through hole or element hole on the optical element insertion plate as required.

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