A tunable vertical cavity surface emitting laser structure

Abstract

The application relates to a tunable vertical cavity surface emitting laser structure, which comprises a vertical cavity surface emitting laser unit, a micro-electro-mechanical system device bonded with the vertical cavity surface emitting laser unit, an independently controllable piezoelectric material structure arranged between the vertical cavity surface emitting laser unit and the micro-electro-mechanical system device, and a control unit connected with the vertical cavity surface emitting laser unit and the micro-electro-mechanical system device, wherein the control unit adjusts the displacement and angle between the vertical cavity surface emitting laser unit and the micro-electro-mechanical system device by controlling the voltage applied to the piezoelectric material structure. The tunable vertical cavity surface emitting laser structure is distinguished from the prior art in function in that coaxial parallel control and bidirectional driving are provided, and the biggest feature of the structure is that a plurality of independently controllable piezoelectric material structures are introduced in the bonding area, so that the preliminary adjustment of the air gap and the coaxial effect of the overall light source device are realized.

Description

Technical Field

[0001] This invention relates to the field of vertical cavity surface-emitting laser (VCSEL) technology, and more specifically to a tunable vertical cavity surface-emitting laser structure. Background Technology

[0002] Optical coherence analysis relies on interference phenomena between a reference wave and an experimental wave, or between two parts of an experimental wave, to measure distance and thickness. Optical coherence tomography (OCT) is a technique for high-resolution, in-depth analysis of samples, including biological samples such as tissues and organs, or industrial samples such as polymers and thin films. OCT is mainly divided into two types: time-domain OCT (TD-OCT) and frequency-domain OCT (FD-OCT). In FD-OCT, a wavelength-tunable laser is typically used as a broadband light source; this type of OCT is called swept-source OCT (SS-OCT). Only one wavelength exists at any given time, using laser wavelength scanning instead of the mechanical scanning of a reference mirror. The signal-to-noise ratio of SS-OCT is fundamentally superior to that of TD-OCT. The core component of swept-source OCT typically uses a wavelength-tunable laser as a broadband light source.

[0003] Tunable lasers used in SS-OCT need to meet multiple requirements. First, they must achieve single-mode operation to ensure high coherence and a long coherence length under operating conditions. Furthermore, the laser's wavelength tuning range must be sufficiently wide to allow for a longer scanning depth. Simultaneously, a high-speed wavelength scanning rate is also a crucial performance indicator, essential for achieving high-resolution imaging. Finally, the control signal for the tuning wavelength should be a simple monotonic function, enabling more precise wavelength tuning and improving system stability and accuracy.

[0004] There are two main fabrication methods for wavelength-tunable lasers as broadband light sources: one is to directly form a microelectromechanical system (MEMS) dielectric mirror on a VCSEL, and the other requires bonding a MEMS mirror device to the VCSEL device. Each method has its advantages and disadvantages. However, the latter method, which involves fabricating the mirror separately and then bonding it, allows for adjustment of the MEMS mirror by pulling it away, reducing the risk of device damage due to rapid mirror descent. Furthermore, since it eliminates the need to directly grow the mirror on the VCSEL, the technology for fabricating MEMS mirrors offers greater flexibility and more structural and material compatibility.

[0005] Currently, wavelength-tunable lasers (VTOL) present several practical challenges as broadband light sources. Fundamentally, these devices achieve wavelength tunability by adjusting the air gap thickness between the VCSEL and the mirror. The first issue is the crucial importance of the air gap thickness, which needs to be precisely matched with the overall device to generate excellent standing wave fields and coupling effects. Existing technologies require the mirror to be positioned under a suitable DC bias before harmonic tuning can occur. This DC bias often reaches tens or hundreds of volts, significantly reducing the miniaturization potential of the VTOL laser system. The second issue is that for VTOL lasers fabricated separately and then joined, a slight angle often forms between the VCSEL and the MEMS mirror, preventing the overall optics from achieving coaxiality. This leads to an increased wavelength range at any given time, decreased coherence of the light source, reduced coherence length, further decreasing the system's scanning depth, and a significant reduction in imaging quality.

[0006] Therefore, existing technologies still need improvement. Summary of the Invention

[0007] To address the problems existing in the prior art as described above, this invention provides a tunable vertical-cavity surface-emitting laser (VCSEL) structure that can greatly alleviate the two practical problems mentioned above. Regarding the first problem, this invention can adjust the distance between the VCSEL and the mirror by adjusting the piezoelectric material. The adjustment voltage is often only a few volts, far less than the DC bias voltage. Furthermore, since no preliminary adjustment of the air gap by the MEMS component is required, the mirror can have a wider tuning range. Regarding the second problem, concerning the coaxial effect of the overall optics, by adjusting the voltage values ​​of the four piezoelectric materials at the bonding points, the mirror and the overall optics can achieve a coaxial effect or present a controlled specific angle.

[0008] Specifically, according to one aspect of the present invention, a tunable vertical-cavity surface-emitting laser (VCSEL) structure is provided, comprising: a VCSEL unit; a microelectromechanical system (MEMS) device coupled to the VCSEL unit; an independently controllable piezoelectric material structure disposed between the VCSEL unit and the MEMS device; and a control unit connected to the VCSEL unit and the MEMS device, wherein the control unit adjusts the displacement and angle between the VCSEL unit and the MEMS device by controlling the voltage applied to the piezoelectric material structure.

[0009] In an embodiment of the present invention, the tunable vertical-cavity surface-emitting laser structure further includes a deformable conductive material disposed between the vertical-cavity surface-emitting laser unit and the microelectromechanical system device, wherein the vertical-cavity surface-emitting laser unit and the microelectromechanical system device are bonded together at least through the piezoelectric material structure and the deformable conductive material.

[0010] In an embodiment of the present invention, the microelectromechanical system device includes a dielectric mirror layer, which includes a dielectric mirror and a dielectric passivation / isolation layer.

[0011] In an embodiment of the present invention, the control unit adjusts the distance and / or angle between the vertical cavity surface-emitting laser unit and the dielectric mirror by controlling the voltage applied to the piezoelectric material in the piezoelectric material structure.

[0012] In an embodiment of the present invention, the piezoelectric material structure is grown on the vertical cavity surface-emitting laser unit.

[0013] In an embodiment of the present invention, the piezoelectric material structure includes a first piezoelectric material electrode disposed on the dielectric passivation / isolation layer, a piezoelectric material disposed on the first piezoelectric material electrode, and a second piezoelectric material electrode disposed on the piezoelectric material and the dielectric passivation / isolation layer, wherein the first piezoelectric material electrode and the second piezoelectric material electrode are electrically isolated by the piezoelectric material, and the plurality of second piezoelectric material electrodes are electrically isolated from each other by the dielectric passivation / isolation layer.

[0014] In an embodiment of the present invention, the vertical cavity surface-emitting laser unit includes a first Bragg mirror, a second Bragg mirror, and an active region disposed between the first Bragg mirror and the second Bragg mirror adjacent to the dielectric mirror. The first Bragg mirror, the dielectric mirror, and the air gap between the first Bragg mirror and the dielectric mirror form a Fabry-Perot resonator.

[0015] In an embodiment of the present invention, the second Bragg reflector, the active region, and a portion of the first Bragg reflector form a first resonant cavity, and another portion of the first Bragg reflector, the air gap, and the dielectric reflector form a second resonant cavity.

[0016] In embodiments of the present invention, the piezoelectric material structure is grown on the microelectromechanical system device, or the piezoelectric material structure is disposed as an independent structure between the vertical cavity surface-emitting laser unit and the microelectromechanical system device.

[0017] In an embodiment of the present invention, the dielectric reflector layer further includes a mask layer disposed on the dielectric reflector, the mask layer including photoresist.

[0018] In embodiments of the present invention, the photoresist comprises polyimide.

[0019] In an embodiment of the present invention, the mask layer is generated through the following method steps:

[0020] S1. Before spin coating, the photoresist is preheated to a first predetermined temperature to increase its fluidity;

[0021] S2. Before spin coating, the substrate including the dielectric mirror is dried at a second predetermined temperature for a first predetermined time;

[0022] S3. Apply photoresist onto the substrate and perform homogenization for a second predetermined time;

[0023] S4. The substrate is pre-baked at a third predetermined temperature for a third predetermined time;

[0024] S5. Fully expose the substrate at the predetermined exposure intensity;

[0025] S6. The substrate is subjected to intermediate baking at a fourth predetermined temperature for a fourth predetermined time;

[0026] S7. Develop the substrate for a fifth predetermined time;

[0027] S8. The substrate is subjected to multiple post-baking processes at gradually increasing temperatures to remove moisture and organic solvents;

[0028] S9. The substrate is further baked at a fifth predetermined temperature for a sixth predetermined time to reduce the adhesion and stress of the photoresist.

[0029] In an embodiment of the present invention, the first predetermined temperature is 20–40°C, the second predetermined temperature is 90–110°C, the third predetermined temperature is 90–110°C, the fourth predetermined temperature is 90–110°C, and the fifth predetermined temperature is 100–180°C; the first predetermined time is 3–8 minutes, the second predetermined time is 20–40 seconds, the third predetermined time is 80–100 seconds, the fourth predetermined time is 100–120 seconds, the fifth predetermined time is 15–35 seconds, and the sixth predetermined time is 60–80 minutes; the gradually increasing temperatures are 80°C, 90°C, and 100°C, and are sustained for 2.5 minutes, 2.5 minutes, and 5 minutes, respectively.

[0030] In an embodiment of the present invention, in step S3, the spin coating is performed at a rotation speed of 2000 rpm to 5000 rpm.

[0031] In an embodiment of the present invention, in step S5, the predetermined exposure intensity is from 250 mJ / cm2 to 650 mJ / cm2.

[0032] In an embodiment of the present invention, in step S7, development is performed using Std 2.38% TMAH.

[0033] In embodiments of the present invention, the piezoelectric material in the piezoelectric material structure includes one or more of polyvinylidene fluoride, polyvinylidene fluoride trifluoroethylene copolymer, polyvinyl alcohol, and lead zirconate titanate, and the deformable conductive material includes one or more of conductive polymer film, metal / polymer composite film, conductive polymer composite film, and conductive oxide composite film.

[0034] In an embodiment of the present invention, the vertical cavity surface-emitting laser unit is one of the following: air column type, buried heterojunction type, oxide confinement type, and proton injection type.

[0035] In embodiments of the present invention, the vertical cavity surface-emitting laser unit is electrically pumped or optically pumped.

[0036] In embodiments of the present invention, the material of the dielectric reflector includes one or more of tantalum oxide, niobium oxide, hafnium oxide, titanium oxide, silicon oxide, and silicon nitride.

[0037] According to another aspect of the present invention, a tunable vertical-cavity surface-emitting laser structure is provided, comprising: a light source unit; a microelectromechanical system (MEMS) device coupled to the light source unit; an independently controllable piezoelectric material structure disposed between the light source unit and the MEMS device; and a control unit connected to the light source unit and the MEMS device, wherein the control unit adjusts the displacement and angle between the light source unit and the MEMS device by controlling the voltage applied to the piezoelectric material structure, wherein the light source unit includes a DFB laser, an ECL laser, an SOA laser, or an LED light source.

[0038] The tunable vertical-cavity surface-emitting laser (VCSEL) structure provided by this invention allows for the coaxial arrangement or controlled presentation of a specific angle of the wavelength-tunable VCSEL by controlling multiple piezoelectric materials. Furthermore, the structure of the resonant cavity combined with the Fabry-Perot resonant cavity provided by this invention reduces the power loss of the device. This invention also proposes a method for protecting silicon-containing dielectric mirrors on a silicon substrate, and this method can protect the dielectric mirrors for up to 7 hours, thereby improving the overall chemical compatibility of the process. Attached Figure Description

[0039] Figure 1This is an exploded perspective view of a tunable vertical-cavity surface-emitting laser structure according to an embodiment of the present invention;

[0040] Figure 2 This is a schematic cross-sectional view of a VCSEL (Void Gap Dielectric Mirror) structure with a partial upper Bragg mirror.

[0041] Figure 3 This is a side view of a tunable vertical-cavity surface-emitting laser structure according to an embodiment of the present invention, wherein the optical ports of the MEMS mirror device are indicated by dashed lines;

[0042] Figure 4 This is a front view of a tunable vertical cavity surface-emitting laser structure with dashed lines according to an embodiment of the present invention, including AA sectional view dividing lines, BB sectional view dividing lines, CC sectional view dividing lines and DD sectional view dividing lines.

[0043] Figure 5 yes Figure 4 AA section view;

[0044] Figure 6 yes Figure 4 BB cross-sectional view;

[0045] Figure 7 yes Figure 4 CC section view;

[0046] Figure 8 yes Figure 4 DD sectional view;

[0047] Figure 9 This is a plan view of a VCSEL according to an embodiment of the present invention;

[0048] Figure 10 This is a plan view of a MEMS according to an embodiment of the present invention;

[0049] Figure 11 This is a front view showing the structure of a tunable vertical-cavity surface-emitting laser with a VCSEL shown by dashed lines; and

[0050] Figure 12 This is a flowchart illustrating a method for protecting a dielectric mirror containing metal oxides or silicon components on a silicon substrate, according to an embodiment of the present invention. Detailed Implementation

[0051] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0052] In the description of the invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "joining," and "connection" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection of two components. The terms "first," "second," "third," and "fourth" do not represent any sequential relationship but are merely distinctions for the convenience of description. Those skilled in the art can understand the specific meaning of the above terms in the invention based on the specific circumstances.

[0053] In applications such as swept-source OCT, which require wavelength tunability, it is necessary to meet requirements such as single-mode operation, wide wavelength tuning range, high-speed wavelength scan rate, and simple monotonic function control signals. Therefore, achieving these requirements is one of the bottlenecks in current swept-source OCT technology. To address this, the present invention provides the following technical solution.

[0054] According to the present invention, a tunable vertical cavity surface-emitting laser structure (also known as a MEMS wavelength-tunable VCSEL structure) is provided, wherein the VCSEL is suitable for laser light sources based on materials such as GaAs or InP. Its functional difference from the prior art lies in that it has coaxial parallel control and bidirectional drive. Its structural difference from general wavelength-tunable vertical cavity surface-emitting lasers is that multiple independently controlled piezoelectric material structures are introduced in the bonding region, thereby achieving preliminary adjustment of the air gap and the coaxial effect of the overall light source device.

[0055] Previous designs could only change the air gap by applying a high voltage to the thin film. However, for applications requiring wavelength changes over a single cycle, the required voltage often reaches tens or hundreds of volts, posing a significant challenge to the integration of MEMS wavelength-tunable VCSEL structures. This invention introduces a piezoelectric material structure (including but not limited to barium lead magnesium oxide piezoelectric ceramics (PZT)). Because it uses a thin film material, only a few volts are needed to change its shape, thus serving as a primary means of air gap adjustment. Subsequently, harmonic tuning is applied to the thin film to complete secondary air gap adjustment. The overall required voltage is far lower than that required for individually adjusting the thin film. Unlike other similar MEMS wavelength-tunable VCSELs that rely on hard connections through gold-to-gold bonding or other spacers, this invention requires the use of a deformable conductive material of appropriate thickness (including but not limited to conductive polymer films). This invention provides a novel technical solution for air gap adjustment using piezoelectric materials for bonding, significantly promoting the efficient integration of VCSELs and MEMS.

[0056] In embodiments of the present invention, the MEMS portion comprises a silicon substrate, a silicon dioxide sacrificial layer serving as a capacitor cavity, a thin-film structure integrated with the cantilever beam, and a dielectric mirror. However, the dielectric mirror portion is processed integrally with respect to the other parts of the MEMS, which poses a challenge to the compatibility of chemical compositions. To protect the integrity of the dielectric mirror during MEMS etching operations, the present invention proposes an inventive process operation. By using patterning of photoresist (e.g., polyimide (PI)) and utilizing special process steps to balance the mechanical strength and viscosity of PI, protection of the silicon-containing dielectric mirror is achieved on the silicon substrate, as described in other parts of the present invention. In testing, this method can protect the dielectric mirror for up to 7 hours.

[0057] This invention relates to a MEMS wavelength-tunable VCSEL structure, but unlike existing tunable VCSELs, its mirror employs a special design. This design utilizes a carefully designed and simulated gallium arsenide (GaAs)-based reflector (DBR) – air gap – dielectric reflector (DBR) structure, instead of a conventional air gap – dielectric reflector. Its advantage lies in forming an additional resonant cavity outside the VCSEL resonant cavity, located at the air gap. This resonant cavity can serve as the primary resonant cavity in the embodiment and / or operating mode, with effective wavelength variations controlled by an electrostatically driven mirror. This design achieves a wider wavelength tuning range with the same displacement variation. Due to the lower voltage requirement, it is more conducive to integration into OCT systems and safer for high-resolution, in-depth analysis of human tissues and organs.

[0058] Furthermore, since the structure of the gallium arsenide (GaAs)-based reflector (DBR)-air gap-medium reflector (DBR) can provide high reflectivity of up to 95%, there is no need to deposit an anti-reflection (AR) coating on the other side of the thin film where the dielectric reflector is located, which reduces the complexity and manufacturing cost of MEMS manufacturing.

[0059] Traditional MEMS mirrors bonded to the active region typically only form a standing wave peak at the active region and the air gap, effectively fusing them into a single resonant cavity. This limits the wavelength tuning effect achieved by adjusting the air gap to the active region. Furthermore, since the active region is in direct contact with the air gap, effective wavelength confinement cannot be achieved there. Consequently, the threshold voltage of MEMS wavelength-tunable VCSELs is higher, resulting in lower output power and more severe heat generation issues for the same injection current. This reduces device lifespan and reliability. To address this, one embodiment of the present invention provides a gallium arsenide (GaAs)-based mirror (DBR) – air gap – dielectric mirror (DBR) structural design that successfully separates the active region and the air gap. The lower DBR – active region – upper DBR (incomplete) form the first resonant cavity, while the upper DBR (incomplete) – air gap – dielectric mirror constitute the second resonant cavity. As an electrically pumped VCSEL, the active region resonant cavity is first limited by the upper and lower DBRs. Therefore, the threshold of MEMS wavelength tunable VCSEL is lower, the output power is greater under the same injection current, and the heat dissipation problem of the device is also improved, which will optimize the device's lifespan and reliability.

[0060] Because of the presence of the second resonant cavity, the influence of the first resonant cavity is reduced during the process of adjusting the air gap by electrostatic drive to achieve wavelength tunability. This improves the control capability of the electrostatically driven mirror to control the effective wavelength, thereby achieving better control results.

[0061] In embodiments of the present invention, the MEMS wavelength-tunable VCSEL structure comprises a MEMS portion and a VCSEL portion, which are bonded together. The MEMS portion includes a silicon substrate, a silicon dioxide sacrificial layer serving as a capacitor cavity, a thin-film structure integrated with the cantilever beam, and a dielectric mirror. The VCSEL portion includes a gallium arsenide substrate, a linearly varying aluminum composition AlGaAs-based lower Bragg mirror (DBR), an InGaAs / GaAsP active region, and a linearly varying aluminum composition AlGaAs-based upper Bragg mirror (DBR). Compared to the AlGaAs-based upper Bragg mirror in a standalone VCSEL device, the upper Bragg mirror portion here is incomplete; this is a specially designed feature. This VCSEL portion initially limits the allowed output wavelength to between 1010-1110 nm, and then, through the MEMS portion, further limits the output wavelength to between 1020-1100 nm, ensuring that only one wavelength of laser light appears at a time. By changing the voltage applied to the capacitor cavity, the size of the air gap can be altered, thereby changing the output wavelength. Furthermore, by adding a high-frequency AC signal to the DC bias, high-speed continuous change of the output wavelength can be achieved.

[0062] In embodiments of the present invention, the MEMS wavelength-tunable VCSEL structure is electrically pumped, which means it can increase integration density while reducing interference from external devices. This will facilitate the integration and optimization of the overall device.

[0063] According to the VCSEL portion provided by the present invention, its body comprises, from bottom to top: a substrate, a lower DBR, an active region, an oxide confinement layer, an upper DBR, a passivation layer, and a coplanar electrode. The coplanar electrode can be made of AuGeNi / Au. The substrate can be, but is not limited to, a GaAs / AlGaAs material system. The passivation layer can be a SiO2 layer.

[0064] The following is for reference. Figures 1-11 This further illustrates the tunable vertical-cavity surface-emitting laser structure provided by the present invention. Specifically, according to an embodiment of the present invention, a tunable vertical-cavity surface-emitting laser structure 100 is provided, such as... Figure 1 and Figure 11As shown, it may include: a vertical-cavity surface-emitting laser (VCSEL) unit 130, which may also be referred to as a VCSEL chip or device 130; a microelectromechanical system (MEMS) device 110 coupled to the VCSEL chip or device 130; an independently controllable piezoelectric material structure disposed between the VCSEL chip or device 130 and the MEMS device 110; and a control unit 120 connected to the VCSEL chip or device 130 and the MEMS device 110, the control unit 120 adjusting the displacement and angle between the VCSEL chip or device 130 and the MEMS device 110 by controlling the voltage applied to the piezoelectric material structure.

[0065] In an embodiment of the present invention, the tunable vertical cavity surface emission laser structure 100 may further include a deformable conductive material disposed between the VCSEL chip or device 130 and the MEMS device 110, wherein the VCSEL chip or device 130 and the MEMS device 110 are bonded together at least through a piezoelectric material structure and a deformable conductive material, as described in other parts of the present invention.

[0066] In embodiments of the present invention, the VCSEL chip or device 130 and the MEMS device 110 are designed and manufactured separately before being combined. Figure 1 In the separated structure shown, the VCSEL chip or device 130 is located above the center of the surface of the MEMS device 110. In the actual manufacturing process, the VCSEL chip or device 130 and the MEMS device 110 are fabricated first, then adjusted to their respective positions, and finally physically connected to complete the overall structure. This separated design improves the flexibility and accuracy of the manufacturing process, thereby ensuring the reliability and stability of the MEMS wavelength-tunable VCSEL structure 100. This invention connects the VCSEL chip or device 130 and the MEMS device 110 at least through a piezoelectric material structure and a deformable conductive material, as described in other parts of this invention.

[0067] In embodiments of the present invention, such as Figure 1 , Figure 3 and Figure 5As shown, the MEMS device 110 may include a substrate wafer material 114, an insulating layer 113 (also referred to as an insulating oxide layer 113), a top silicon layer 112A, a cantilever beam structure layer 112B, a disk layer 112C, and a dielectric mirror layer. The dielectric mirror layer includes a centrally located dielectric mirror 111B and a dielectric passivation / isolation layer 111A. The substrate wafer material 114 is located at the bottom of the MEMS device 110. The insulating layer 113 is disposed on the substrate wafer material 114, and the top silicon layer 112A, cantilever beam structure layer 112B, and disk layer 112C are disposed on the insulating layer 113. The top silicon layer 112A, cantilever beam structure layer 112B, and disk layer 112C are on the same layer, but are separated into the top silicon layer 112A, cantilever beam structure layer 112B, and disk layer 112C after surface patterning to distinguish different functions. The top silicon layer 112A is located above the substrate wafer material 114 and is added thereon. The dielectric mirror 111B is located above the disk layer 112C and, together with other layers, forms part of the optical feedback loop in the MEMS wavelength-tunable VCSEL structure 100. By forming the dielectric mirror 111B on the disk layer 112C, light reflection and amplification can be achieved, thereby realizing the stable output of the wavelength-tunable VCSEL. The cantilever beam structure layer 112B consists of a series of cantilever beams, which are not directly connected to other layers and can be bent downwards to increase the vibration amplitude. The design of the cantilever beam structure layer 112B enables the wavelength tuning function of the MEMS wavelength-tunable VCSEL structure 100, which can be controlled by electrical or mechanical means. Therefore, this layered structural design can better realize the function of the MEMS wavelength-tunable VCSEL structure, thus meeting the application requirements of different occasions and needs.

[0068] The top silicon layer 112A is made of lightly doped silicon with a resistivity greater than 1 ohm-cm. This minimizes the absorption of transmitted light by free carriers, maximizing the film's light transmittance and internal reflectivity. Simultaneously, to achieve electrical contact, a highly doped surface layer is created on the film surface using methods such as ion implantation. This method allows for highly localized doping, reducing overall light absorption and thus improving the performance and stability of the MEMS wavelength-tunable VCSEL structure 100. In summary, the design of the top silicon layer 112A requires a balance between light transmittance and electrical contact performance. Using lightly doped silicon maximizes its light transmittance, while achieving electrical contact through locally highly doped areas.

[0069] An insulating layer 113 is used to separate the top silicon layer 112A from the substrate wafer material 114. This insulating layer is typically fabricated using a buried silicon dioxide method, which offers excellent insulation properties and dimensional controllability, significantly reducing the interaction between the top silicon layer 112A and the substrate wafer material 114. The insulating layer 113 is usually formed using techniques such as chemical vapor deposition, physical vapor deposition, and ion implantation, enabling high-quality fabrication. By separating the top silicon layer 112A from the substrate wafer material 114, electrical and optical interactions between them are avoided, thereby ensuring the performance and stability of the MEMS wavelength-tunable VCSEL structure 100.

[0070] Typically, silicon-on-insulator (SOI) wafers are used to provide a combination of substrate wafer material 114, insulating oxide layer 113, and top silicon layer 112A. An SOI wafer is actually a three-layer structure consisting of two silicon layers separated by an insulating layer. Typically, the upper layer of the SOI wafer is a silicon layer, serving as the basis for device fabrication and integration, while the lower layer is the substrate wafer material 114. The insulating layer isolates the upper and lower silicon layers, preventing interference and interaction between either layer and the external environment. This structure not only improves the performance and reliability of switching devices but also reduces the space occupied by the devices. Therefore, SOI wafers are commonly used as the base material in micro / nano-scale devices such as MEMS wavelength-tunable VCSEL structures 100.

[0071] When fabricating the MEMS wavelength-tunable VCSEL structure 100, the insulating layer 113 is typically used as a sacrificial / release layer, partially removed to release the cantilever beam structure layer 112B and the disk layer 112C. In this process, the bare substrate wafer material 114 is exposed, and these layers are then surrounded by the remaining insulating layer 113 and the top silicon layer 112A. During operation of the MEMS wavelength-tunable VCSEL structure 100, the remaining portion of the insulating layer 113 provides electrical isolation between the top silicon layer 112A and the substrate material 114. This is crucial for avoiding mutual interference and influence between devices on the wafer, thereby ensuring the performance and stability of the entire device. Therefore, the insulating layer 113 plays a vital role in the MEMS wavelength-tunable VCSEL structure 100. Its formation is typically achieved using buried silicon dioxide (SOI) methods, which provide good insulation properties and dimensional controllability. SOI wafers are commonly used to provide the combination of substrate wafer material 114, insulating oxide layer 113, and top silicon layer 112A, and are widely used in micro / nano-scale devices.

[0072] The capacitive cavity between the top silicon layer 112A and the substrate material 114 is controlled by the positive cathode of the MEMS device 110, including an anode 115R on the top silicon layer 112A and a cathode 115L on the substrate material 114, such as... Figure 1 , Figure 6 , Figure 7 and Figure 10 As shown. In Figure 6 In the illustrated embodiment, the cathode 115L of the substrate wafer material 114 is fabricated by forming a permeable dielectric passivation / isolation layer 111A, a top silicon layer 112A, and an insulating layer 113. The cathode 115L is deposited where the substrate wafer material 114 is exposed. Figure 7 In the illustrated embodiment, the anode 115R of the disk surface layer 112C is fabricated via a dielectric passivation / isolation layer 111A, and the anode 115R is deposited at the exposed surface of the disk surface layer 112C. Further reference... Figure 10 The cathode 115L is on the substrate material 114, and the anode 115R is on the top silicon layer 112A. They are electrically isolated by an insulating layer 113 (buried silicon dioxide) and provide a driving voltage for the capacitor cavity 149 of the MEMS device 110. The left bonding electrode 138L and the right bonding electrode 138R are both formed by sputtering onto the dielectric passivation / isolation layer 111A. The left bonding electrode 138L and the right bonding electrode 138R are electrically isolated by the dielectric passivation / isolation layer 111A and provide a driving current for the VCSEL chip or device 130. The dielectric mirror 111B is grown on the disk layer 112C, and the substrate wafer material 114 can be seen in the gaps of the cantilever beam structure layer 112B because the insulating layer 113 has been released. The insulating layer 113 under the disk layer 112C and the cantilever beam structure layer 112B has been completely released, forming the capacitor cavity 149.

[0073] The dielectric mirror layer, after being patterned to create different functional regions, has a repeating, stacked structure. Its composition is an insulator, and it is therefore divided into a central dielectric mirror 111B and a dielectric passivation / isolation layer 111A. The dielectric mirror 111B has a different structure and is closely related to the VCSEL chip or device 130. The dielectric mirror 111B can be composed of various materials arranged in combination, including but not limited to various optical thin film materials, such as tantalum oxide, niobium oxide, hafnium oxide, titanium oxide, silicon oxide, and silicon nitride. The dielectric mirror 111B uses titanium oxide and tantalum oxide with a high refractive index difference, consisting of six pairs of titanium oxide / tantalum oxide with thicknesses of 172.75 nm and 96.49 nm, respectively. For a target wavelength of 1060 nm, the dielectric mirror 111B can provide a reflectivity of up to 95%.

[0074] Since dielectric mirrors 111B are mostly metal oxides or silicon-containing compounds, compatibility with chemical compositions presents certain challenges. To protect the dielectric mirror 111B without affecting the overall process, this invention innovatively employs photoresist as a mask layer. This mask layer can be used for photolithography, adheres to the silicon surface, and possesses the mechanical strength required for the process. In this embodiment, the dielectric mirror layer further includes a mask layer (not shown) disposed on the dielectric mirror 111B. This mask layer may include photoresist and can be formed using the method described in this invention 500, thereby providing protection for the dielectric mirror 111B. In one embodiment, the photoresist may include polyimide (PI). Through a special process step balancing the mechanical strength and viscosity of PI, silicon-containing dielectric mirrors can be protected on a silicon substrate. In testing, this method can protect the dielectric mirror for up to 7 hours.

[0075] The method 500 of the present invention is specifically a method for protecting a dielectric mirror containing metal oxides or silicon components on a silicon substrate, which may include the following steps:

[0076] S1. Before spin coating, the photoresist is preheated to a first predetermined temperature to increase its fluidity;

[0077] S2. Before spin coating, the substrate including the dielectric mirror is dried at a second predetermined temperature for a first predetermined time;

[0078] S3. Apply photoresist onto the substrate and perform homogenization for a second predetermined time;

[0079] S4. The substrate is pre-baked at a third predetermined temperature for a third predetermined time;

[0080] S5. Fully expose the substrate at the predetermined exposure intensity;

[0081] S6. The substrate is subjected to intermediate baking at a fourth predetermined temperature for a fourth predetermined time;

[0082] S7. Develop the substrate for a fifth predetermined time;

[0083] S8. The substrate is subjected to multiple post-baking processes at gradually increasing temperatures to remove moisture and organic solvents;

[0084] S9. The substrate is further baked at a fifth predetermined temperature for a sixth predetermined time to reduce the adhesion and stress of the photoresist.

[0085] In an embodiment of the present invention, the substrate is a patterned metal oxide mirror film on an SOI silicon wafer.

[0086] In an embodiment of the present invention, the first predetermined temperature is 20–40°C, the second predetermined temperature is 90–110°C, the third predetermined temperature is 90–110°C, the fourth predetermined temperature is 90–110°C, and the fifth predetermined temperature is 100–180°C; the first predetermined time is 3–8 minutes, the second predetermined time is 20–40 seconds, the third predetermined time is 80–100 seconds, the fourth predetermined time is 100–120 seconds, the fifth predetermined time is 15–35 seconds, and the sixth predetermined time is 60–80 minutes; the gradually increasing temperatures are 80°C, 90°C, and 100°C, and are sustained for 2.5 minutes, 2.5 minutes, and 5 minutes, respectively.

[0087] In an embodiment of the present invention, in step S3, the spin coating is performed at a rotation speed of 2000 rpm to 5000 rpm.

[0088] In an embodiment of the present invention, in step S5, the predetermined exposure intensity is from 250 mJ / cm2 to 650 mJ / cm2.

[0089] In an embodiment of the present invention, in step S7, development is performed using Std 2.38% TMAH.

[0090] An embodiment of method 500 is further described below, which may include the following steps:

[0091] 1. In a container such as a dropper bottle, the PI is first heated to 30 degrees Celsius before homogenization to increase its fluidity.

[0092] 2. Before homogenization, dry the substrate at 100℃ for 5 minutes.

[0093] 3. Drop PI onto the substrate and perform homogenization at 4000 rpm for 30 seconds. After homogenization, the PI will automatically level itself on the substrate.

[0094] 4. Pre-bake the substrate at 100℃ for 90 seconds.

[0095] 5. Exposure intensity 350mJ / cm2, full exposure.

[0096] 6. Dry the substrate at 100℃ for 110 seconds.

[0097] 7. Develop the substrate using Std 2.38% TMAH for 25 seconds.

[0098] 8. Post-drying: First step at 80℃ for 2.5 min, then at 90℃ for 2.5 min, then at 100℃ for 5 min. This step mainly removes moisture and organic solvents.

[0099] 9. The second post-baking step is at 130℃ for 65 minutes. This step mainly reduces the viscosity of PI, improves its mechanical strength, and strictly controls the temperature to reduce PI stress.

[0100] The above method enables the protection of silicon-containing dielectric mirrors on silicon substrates, and this method can protect the dielectric mirrors for up to 7 hours, thereby improving the chemical composition compatibility of the overall process.

[0101] In embodiments of the present invention, the portion used as the metal bonding electrode includes a left bonding electrode 138L and a right bonding electrode 138R, such as Figure 1 , Figure 3 , Figure 5 and Figure 10 The portion near the center is used for bonding to the VCSEL chip or device 130, while the portion away from the center is bonded with gold wire to introduce the drive current. The metal is formed by sputtering AuGeNi / Au and deposited on its surface. to thickness.

[0102] In embodiments of the present invention, the VCSEL chip or device 130 may be one of the following: air-column type, buried heterojunction type, oxide-confined type, and proton-implanted type. The VCSEL chip or device 130 may be electrically pumped or optically pumped.

[0103] In embodiments of the present invention, the VCSEL chip or device 130 includes a first Bragg reflector adjacent to a dielectric reflector, a second Bragg reflector, and an active region disposed between the first and second Bragg reflectors. Figure 2In the illustrated embodiment, the first Bragg reflector can be an upper Bragg reflector (DBR) 134, and the second Bragg reflector can be an n-type lower Bragg reflector (DBR) 132. The VCSEL chip or device 130 also includes a substrate 131, which can be a GaAs substrate. The VCSEL chip or device 130 is epitaxially grown on the substrate 131 using metal-organic chemical vapor deposition (MOCVD), and the growth sequence from bottom to top on the GaAs substrate 131 is the n-type lower Bragg reflector (DBR) 132, the active region 133, the oxide confinement layer (not shown), the upper Bragg reflector (DBR) 134, and the passivation layer (not shown). The lower Bragg reflector (DBR) 132 consists of 42 pairs of n-type (Si-doped) Al0.90Ga0.10As / Al0.12Ga0.88As. The active region 133 consists of 5 pairs of 6nm-thick GaAs quantum wells and 8nm-thick Al0.30Ga0.70As, with a center wavelength of 1060nm. The upper Bragg reflector (DBR) 134 consists of 17 pairs of p-type (C-doped) Al0.90Ga0.10As / Al0.12Ga0.88As. The oxide confinement layer 186, located between the active region 133 and the upper Bragg reflector (DBR) 134, is 30nm-thick Al0.98Ga0.02As.

[0104] Further reference Figure 2 A distributed reflection laser is constructed by a lower Bragg reflector (DBR) 132, a partial upper Bragg reflector (DBR) 134, and an active region 133 between them, with the active region 133 serving as the first resonant cavity. The partial upper Bragg reflector (DBR) 134, a dielectric reflector 111B, and an air gap 143 between them constitute a Fabry-Perot resonant cavity. The Fabry-Perot resonant cavity is composed of two reflectors, the distance between which is called the cavity length. When a light beam enters the resonant cavity through the outer surface reflector, the light undergoes multiple reflections within the cavity, and its frequency is related to the cavity length. If the wavelength of the light source matches the cavity length under certain conditions, such as the wavelength being an integer multiple of the cavity length, the steady state of the light accumulates in the cavity and reaches the wavelength required for resonance. When the resonance reaches its peak, energy accumulates in the cavity and is reflected back out. When the light within the cavity is amplified to a sufficient intensity, the conditions for a laser are met.

[0105] Since the MEMS wavelength-tunable VCSEL structure 100 primarily achieves wavelength tuning by changing the size of the air gap 143, forming the air gap 143 into a separate Fabry-Perot resonator is more advantageous for the accumulation and emission of the target wavelength. In other patents, the air gap 143 is placed together with the active region 133, and their standing wave field distributions show that the air gap 143 and the active region 133 have the same intensity. However, the standing wave field distribution of forming the air gap 143 into a separate Fabry-Perot resonator shows that the Fabry-Perot resonator at the air gap 143 is the dominant resonator, and its intensity is more prominent than that at the active region 133.

[0106] The first resonant cavity, in its active region 133, allows an output wavelength limited to the range of 1010-1110 nm, while the Fabry-Perot resonant cavity at the air gap 143 further restricts the output wavelength to the range of 1020-1100 nm, ensuring that only one wavelength of laser light appears at a time. Standing wave field distribution shows that the loss of the standalone Fabry-Perot resonant cavity is less than that of the resonant cavity formed by combining the air gap 143 and the active region 133. By changing the voltage applied to the capacitor cavity, the size of the air gap can be altered, thereby changing the output wavelength. Adding a high-frequency AC signal to a DC bias allows for high-speed, continuous changes in the output wavelength.

[0107] refer to Figure 9 The VCSEL chip or device 130 has a specially patterned first electrode 136L and a second electrode 136R on its surface. The light exit aperture is located at the center of the upper Bragg mirror (DBR) 134. During assembly, the rectangular region to the left of the first electrode 136L of the VCSEL chip or device 130 is bonded to the left bonding electrode 138L of the MEMS device 110 via a deformable conductive material 137L. The rectangular region to the right of the second electrode 136R of the VCSEL chip or device 130 is bonded to the right bonding electrode 138R of the MEMS device 110 via a deformable conductive material 137R. Through the left bonding electrode 138L and the right bonding electrode 138R, they are connected to external circuitry to provide drive current to the VCSEL chip or device 130.

[0108] In embodiments of the present invention, the VCSEL chip or device 130 and the MEMS device 110 are connected via a deformable conductive material and a piezoelectric material structure (including a first piezoelectric electrode, a piezoelectric material, and a second piezoelectric electrode). That is, the VCSEL chip or device 130 is located above the center of the surface of the MEMS device 110 and is connected via the deformable conductive material and the piezoelectric material structure. Figure 1 , Figure 3 , Figure 5 , Figure 8 , Figure 10 and Figure 11 In the illustrated embodiment, the first electrode of the piezoelectric material can be the upper electrode 170A / B / C / D of the piezoelectric material, the piezoelectric material can be piezoelectric material 173A / B / C / D, and the second electrode of the piezoelectric material can be the lower electrode 171 of the piezoelectric material. Figure 10 As shown, piezoelectric materials 173A / B / C / D can be located at the four corners surrounding the center of the MEMS device 110, thus forming four bonding regions. The control unit 120 adjusts the distance and / or angle between the VCSEL chip or device 130 and the dielectric mirror 111B by controlling the voltage applied to the piezoelectric materials 173A / B / C / D. The upper electrode 170A / B / C / D and the lower electrode 171 of the piezoelectric material are formed by sputtering AuGeNi / Au, with a surface deposition thickness of [missing information]. to Piezoelectric materials 173A / B / C / D include, but are not limited to, polyvinylidene fluoride (PVDF), polyvinylidene fluoride trifluoroethylene copolymer (P(VDF-TrFE)), polyvinyl alcohol (PVA), lead zirconate titanate (PZT), etc.

[0109] In one embodiment of the present invention, the piezoelectric material structure may be grown on the VCSEL chip or device 130. In other embodiments of the present invention, the piezoelectric material structure may be grown on the MEMS device 110, or the piezoelectric material structure may be disposed as an independent structure between the VCSEL chip or device 130 and the MEMS device 110.

[0110] The following example uses the growth of piezoelectric material structures on VCSEL chips or devices 130 as an example, combined with... Figure 8 The process is as follows: First, the piezoelectric material lower electrode 171 is sputtered onto the dielectric passivation / isolation layer 111A and patterned, leaving metal electrode leads. Then, piezoelectric materials 173A / B / C / D are grown by magnetron sputtering at the locations where the piezoelectric material lower electrode 171 and the piezoelectric material upper electrodes 170A / B / G / D overlap, and patterned. The sputtered material completely encapsulates a portion of the piezoelectric material lower electrode 171, achieving electrical isolation between the piezoelectric material lower electrode 171 and the piezoelectric material upper electrodes 170A / B / G / D. The piezoelectric materials 173A / B / C / D are independent of each other and completely cover the corresponding piezoelectric material lower electrode 171. The piezoelectric material upper electrode 170A / B / C / D is grown on the piezoelectric material 173A / B / C / D and the dielectric passivation / isolation layer 111A. The piezoelectric material upper electrode 170A / B / C / D and the piezoelectric material lower electrode 171 are electrically isolated through the piezoelectric material 173A / B / C / D. The piezoelectric material upper electrode 170A / B / C / D is electrically isolated from each other through the dielectric passivation / isolation layer 111A.

[0111] refer to Figure 8 This illustrates the bonding of one of the piezoelectric material structures to a VCSEL chip or device 130. The VCSEL chip or device 130 also includes pads corresponding to the piezoelectric material structure. Figure 8 In the illustrated embodiment, a pad 172D is shown that corresponds to the upper piezoelectric electrode 170D, the piezoelectric material 173D, and the lower piezoelectric material electrode 171D, and is bonded to the upper piezoelectric material electrode 170D, thereby achieving bonding between the VCSEL chip or device 130 and the MEMS device 110 through the piezoelectric material structure. Figure 9 In the illustrated embodiment, four pads 172A / B / C / D are shown at the four corners of the surface of the VCSEL chip or device 130.

[0112] In embodiments of the present invention, the piezoelectric material may include one or more of polyvinylidene fluoride, polyvinylidene fluoride trifluoroethylene copolymer, polyvinyl alcohol, and lead zirconate titanate, and the deformable conductive material may include one or more of conductive polymer film, metal / polymer composite film, conductive polymer composite film, and conductive oxide composite film.

[0113] refer to Figure 3 The image shows the optical port 150 of the mirror device of the MEMS device 110, indicated by dashed lines. The optical port 150 can be used when the dielectric mirror 111B is used as an output reflector or for monitoring, and can extend from the distal side of the substrate wafer material 114 to the film structure. In some cases, if the dielectric mirror 111B is used as a back reflector, the optical port 150 is not necessary.

[0114] Further reference Figure 5 The optical port 150 has a generally inwardly sloping sidewall 152 that terminates at the port opening 151. Therefore, the disk layer 112C can be observed through the distal side of the substrate wafer material 114.

[0115] like Figure 5 As shown, the thickness of the insulating layer 113 defines the length of the capacitor cavity 149. Currently, the thickness of the insulating layer 113 is between 1 and 10 micrometers. A general rule of thumb is that, to prevent electrostatic attraction, electrostatic components can be tuned within a range not exceeding one-third of the distance between the capacitor cavities.

[0116] A capacitor cavity 149 is located between the disk layer 112C and the substrate wafer material 114. The disk layer 112C is a floating portion and can be displaced and tuned by an applied voltage. The disk layer 112C is connected via an anode 115R, and the substrate wafer material 114 is connected via a cathode 115L. The potential between the substrate wafer material 114 and the disk layer 112C will generate an electrostatic attraction that pulls the disk layer 112C toward the substrate wafer material 114.

[0117] Details regarding how the VCSEL chip or device 130 is coupled to the MEMS device 110, such as Figure 5 As shown, the left bonding electrode 138L and right bonding electrode 138R of the MEMS device 110 are bonded to the first electrode 136L and second electrode 136R of the VCSEL chip or device 130 via a deformable conductive material 137R and 137L. These metal layers are electrically isolated. Specifically, the left bonding electrode 138L and right bonding electrode 138R of the MEMS device 110 are separated by a dielectric passivation / isolation layer 111A; the first electrode 136L and second electrode 136R of the VCSEL chip or device 130 are isolated from the rest of the VCSEL chip or device 130 via a passivation layer of the VCSEL chip or device 130. The first electrode 136L and second electrode 136R of the VCSEL chip or device 130 and the passivation layer do not interfere with optical operation because they do not extend into the free space portion of the laser optical cavity, i.e., in the region of the air gap 143. All of the above metal electrodes are sputtered AuGeNi / Au form.

[0118] In embodiments of the present invention, the minimum oxide thickness is determined by the required voltage isolation, with a nominal oxide decomposition pressure of 1000V / µm. Therefore, for 200V isolation, the required oxide thickness is 200nm, and it is recommended to double this thickness to obtain a margin. Consequently, the passivation layer of the VCSEL chip or device 130 and the dielectric passivation / isolation layer 111A of the MEMS device 110 should have a thickness greater than 400nm.

[0119] In an embodiment of the present invention, the thickness of the metal bonding is per layer The thickness of deformable conductive materials 137R and 137L is approximately... The passivation layer 135 has a thickness of approximately 400 nm. Based on this, the size of the air gap 143 is 2120 nm.

[0120] In an embodiment of the present invention, the control unit 120 may be a control unit commonly used in the art, which may be electrically connected to the VCSEL chip or device 130 and the MEMS device 110 respectively, and provide corresponding electrical control for each component of the MEMS wavelength tunable VCSEL structure 100 as needed.

[0121] The tunable vertical-cavity surface-emitting laser structure 100 provided by this invention allows for the coaxial arrangement or controlled presentation of a specific angle of the wavelength-tunable vertical-cavity surface-emitting laser by controlling multiple piezoelectric materials. Furthermore, the structure of the resonant cavity combined with the Fabry-Perot resonant cavity provided by this invention reduces the power loss of the device.

[0122] Furthermore, it should be understood that the above embodiments are illustrated using a vertical cavity surface-emitting laser unit as the light source; however, the concept of the present invention is equally applicable to DFB lasers, ECL lasers, SOA lasers, or LED light sources.

[0123] Specifically, according to another embodiment of the present invention, a tunable vertical-cavity surface-emitting laser structure is also provided, comprising: a light source unit; a microelectromechanical system (MEMS) device coupled to the light source unit; an independently controllable piezoelectric material structure disposed between the light source unit and the MEMS device; and a control unit connected to the light source unit and the MEMS device, wherein the control unit adjusts the displacement and angle between the light source unit and the MEMS device by controlling the voltage applied to the piezoelectric material structure, wherein the light source unit includes a DFB laser, an ECL laser, an SOA laser, or an LED light source.

[0124] It should be understood that, without conflict, all embodiments, features, and advantages of the vertical-cavity surface-emitting laser unit described above according to this application are equally applicable to DFB lasers, ECL lasers, SOA lasers, or LED light sources. That is, all embodiments and variations of the vertical-cavity surface-emitting laser unit described above can be directly transferred to DFB lasers, ECL lasers, SOA lasers, or LED light sources and are directly incorporated herein. For the sake of brevity, they will not be repeated here.

[0125] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications or equivalent substitutions made to the present invention without departing from the spirit and scope thereof should be covered within the protection scope of the claims of the present invention.

Claims

1. A tunable vertical-cavity surface-emitting laser structure, characterized in that, include: Vertical-cavity surface-emitting laser unit; Microelectromechanical systems (MEMS) devices coupled to the vertical-cavity surface-emitting laser unit; An independently controllable piezoelectric material structure disposed between the vertical cavity surface-emitting laser unit and the microelectromechanical system device; and A control unit connected to the vertical-cavity surface-emitting laser unit and the microelectromechanical system (MEMS) device, wherein the control unit adjusts the displacement and angle between the vertical-cavity surface-emitting laser unit and the MEMS device by controlling the voltage applied to the piezoelectric material structure.

2. The tunable vertical-cavity surface-emitting laser structure according to claim 1, characterized in that, The device further includes a deformable conductive material disposed between the vertical cavity surface-emitting laser unit and the microelectromechanical system (MEMS) device, wherein the vertical cavity surface-emitting laser unit and the MEMS device are bonded together at least through the piezoelectric material structure and the deformable conductive material.

3. The tunable vertical-cavity surface-emitting laser structure according to claim 2, characterized in that, The microelectromechanical system device includes a dielectric mirror layer, which includes a dielectric mirror and a dielectric passivation / isolation layer.

4. The tunable vertical-cavity surface-emitting laser structure according to claim 3, characterized in that, The control unit adjusts the distance and / or angle between the vertical cavity surface-emitting laser unit and the dielectric mirror by controlling the voltage applied to the piezoelectric material in the piezoelectric material structure.

5. The tunable vertical-cavity surface-emitting laser structure according to claim 3, characterized in that, The piezoelectric material structure is grown on the vertical cavity surface-emitting laser unit.

6. The tunable vertical-cavity surface-emitting laser structure according to claim 5, characterized in that, The piezoelectric material structure includes a first piezoelectric material electrode disposed on the dielectric passivation / isolation layer, a piezoelectric material disposed on the first piezoelectric material electrode, and a second piezoelectric material electrode disposed on the piezoelectric material and the dielectric passivation / isolation layer, wherein the first piezoelectric material electrode and the second piezoelectric material electrode are electrically isolated by the piezoelectric material, and the plurality of second piezoelectric material electrodes are electrically isolated from each other by the dielectric passivation / isolation layer.

7. The tunable vertical-cavity surface-emitting laser structure according to claim 4, characterized in that, The vertical cavity surface-emitting laser unit includes a first Bragg mirror, a second Bragg mirror, and an active region disposed between the first Bragg mirror and the second Bragg mirror, adjacent to the dielectric mirror. The first Bragg mirror, the dielectric mirror, and the air gap between the first Bragg mirror and the dielectric mirror form a Fabry-Perot resonator.

8. The tunable vertical-cavity surface-emitting laser structure according to claim 7, characterized in that, The second Bragg reflector, the active region, and a portion of the first Bragg reflector form a first resonant cavity, and another portion of the first Bragg reflector, the air gap, and the dielectric reflector form a second resonant cavity.

9. The tunable vertical-cavity surface-emitting laser structure according to claim 3, characterized in that, The piezoelectric material structure is grown on the microelectromechanical system device, or the piezoelectric material structure is disposed as an independent structure between the vertical cavity surface-emitting laser unit and the microelectromechanical system device.

10. The tunable vertical-cavity surface-emitting laser structure according to claim 3, characterized in that, The dielectric mirror layer further includes a mask layer disposed on the dielectric mirror, the mask layer comprising photoresist.

11. The tunable vertical-cavity surface-emitting laser structure according to claim 10, characterized in that, The photoresist includes polyimide.

12. The tunable vertical-cavity surface-emitting laser structure according to claim 10, characterized in that, The mask layer is generated through the following steps: S1. Before spin coating, the photoresist is preheated to a first predetermined temperature to increase its fluidity; S2. Before spin coating, the substrate including the dielectric mirror is dried at a second predetermined temperature for a first predetermined time; S3. Apply photoresist onto the substrate and perform homogenization for a second predetermined time; S4. The substrate is pre-baked at a third predetermined temperature for a third predetermined time; S5. Fully expose the substrate at the predetermined exposure intensity; S6. The substrate is subjected to intermediate baking at a fourth predetermined temperature for a fourth predetermined time; S7. Develop the substrate for a fifth predetermined time; S8. The substrate is subjected to multiple post-baking processes at gradually increasing temperatures to remove moisture and organic solvents; S9. The substrate is further baked at a fifth predetermined temperature for a sixth predetermined time to reduce the adhesion and stress of the photoresist.

13. The tunable vertical-cavity surface-emitting laser structure according to claim 12, characterized in that, The first predetermined temperature is 20–40°C, the second predetermined temperature is 90–110°C, the third predetermined temperature is 90–110°C, the fourth predetermined temperature is 90–110°C, and the fifth predetermined temperature is 100–180°C; the first predetermined time is 3–8 minutes, the second predetermined time is 20–40 seconds, the third predetermined time is 80–100 seconds, the fourth predetermined time is 100–120 seconds, the fifth predetermined time is 15–35 seconds, and the sixth predetermined time is 60–80 minutes; the gradually increasing temperatures are 80°C, 90°C, and 100°C, and are sustained for 2.5 minutes, 2.5 minutes, and 5 minutes, respectively.

14. The tunable vertical-cavity surface-emitting laser structure according to claim 12, characterized in that, In step S3, the spin coater is rotated at a speed of 2000 rpm to 5000 rpm.

15. The tunable vertical-cavity surface-emitting laser structure according to claim 14, characterized in that, In step S5, the predetermined exposure intensity is from 250 mJ / cm2 to 650 mJ / cm2.

16. The tunable vertical-cavity surface-emitting laser structure according to claim 14, characterized in that, In step S7, development is performed using Std 2.38% TMAH.

17. The tunable vertical-cavity surface-emitting laser structure according to claim 2, characterized in that, The piezoelectric material in the piezoelectric material structure includes one or more of polyvinylidene fluoride, polyvinylidene fluoride trifluoroethylene copolymer, polyvinyl alcohol, and lead zirconate titanate, and the deformable conductive material includes one or more of conductive polymer film, metal / polymer composite film, conductive polymer composite film, and conductive oxide composite film.

18. The tunable vertical-cavity surface-emitting laser structure according to claim 1, characterized in that, The vertical cavity surface-emitting laser unit is one of the following: air column type, buried heterojunction type, oxide confinement type, and proton injection type.

19. The tunable vertical-cavity surface-emitting laser structure according to claim 1, characterized in that, The vertical cavity surface-emitting laser unit is electrically pumped or optically pumped.

20. The tunable vertical-cavity surface-emitting laser structure according to claim 3, characterized in that, The medium reflector is made of one or more of the following materials: tantalum oxide, niobium oxide, hafnium oxide, titanium oxide, silicon oxide, and silicon nitride.

21. A tunable vertical-cavity surface-emitting laser structure, characterized in that, include: Light source unit; Microelectromechanical systems (MEMS) devices coupled to the light source unit; An independently controllable piezoelectric material structure disposed between the light source unit and the microelectromechanical system device; as well as A control unit connected to the light source unit and the microelectromechanical system (MEMS) device adjusts the displacement and angle between the light source unit and the MEMS device by controlling the voltage applied to the piezoelectric material structure. The light source unit includes a DFB laser, an ECL laser, an SOA laser, or an LED light source.

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