TWM400149U - Compact external cavity laser system with wavelength tuning by using a silicon flexure - Google Patents

Abstract

This invention relates to the wavelength tuning mechanism of an external cavity diode laser system. The characteristic of the device is to use a silicon based flexure applied to the laser system. There is an optical grating attach to the front side of the silicon flexure which will diffract the laser beam and feed it back to the laser diode (fixed end). The rest of the laser power will penetrate through the grating and become the output beam. Besides, there are two piezo actuators mount on the backside of the silicon flexure and can be activated by the electrical voltage. The silicon flexure deflects toward the laser diode according to the amount of the voltage input to the piezo actuators. Meanwhile, the optical grating is mounted on the front side of the silicon flexure. Thus, when the silicon flexure is pushed by the piezo actuator, the grating moved toward to the laser diode side simultaneously. Therefore, the distance between the laser diode and grating (laser cavity length) will be changed as well. Then the lasing wavelength is also changing along with the cavity length. The laser wavelength tuning can be achieved by the silicon flexure. The continuous wavelength tuning can be performed by applying different amount of the input voltage to the piezo actuators. The more voltage applied to the piezo actuators, the more displacement silicon flexure can make. Hence, the lasing wavelength can be tuned further. In addition, when the piezo actuator pushes flexure, the spring constant of the silicon flexure substantially influences the displacement of the grating and the wavelength tuning range. Therefore, the appreciate wavelength tuning range can be achieved by designing the proper geometry and dimensions of the silicon flexure.

Description

V. New description: [New technical field] The creation of "small external cavity laser system using 矽 spring element to adjust the wavelength" is used for the design of the general external cavity laser system, mainly for the external cavity laser system. The volume does not need to occupy a large area. [Prior Art] A general external cavity laser system uses a flexible metal structure as a wavelength adjustment mechanism, and the grating is mounted at a 45 degree angle to the metal structure. A metal structure device, usually on the back side of the grating, is used to adjust the length and wavelength of the laser outer cavity. However, this flexible metal structure tends to be too bulky and cumbersome, and requires a piezoelectric actuator with a large thrust (large size) to meet the laser wavelength adjustment range. In addition, the processing accuracy of this metal structure at each production is difficult to control. Furthermore, the flexible structure made of 'metal materials tends to be deformed by changes in the ambient temperature', which causes the wavelength of the laser to drift. Therefore, in combination with the above points, the general external cavity laser cannot shrink the overall system too small, which is often troublesome and inconvenient for users who need many external cavity laser systems at the same time. The "Tunable Laser System Having an Adjustable External Cavity" disclosed in U.S. Patent No. 6,690,690, B. The design is still based on a flexible metal structure to adjust the wavelength. "Compact External Cavity MID-IR Optical Lasers" disclosed in US Pat. No. 20080298406 A1, the grating is mounted on a metal turret for returning the laser beam to the laser diode at a specific angle. . Although the above-mentioned creative design can directly eliminate the M400149's flexible metal structure to adjust the length of the laser outer cavity, it still has to be operated by a metal grating turret, and the volume of the overall laser system cannot be reduced. . U.S. Patent No. 20050105565A1 uses a circular interference film of different thickness to rotate on a rotating member to a specific film thickness position to achieve the purpose of varying the length and wavelength of the laser outer cavity. However, this rotating element is driven by an electric motor, and the noise generated when the motor rotates will affect the stability of the laser wavelength. In addition, the inclusion of an electric motor in the laser system will result in a larger overall volume. US Patent US 20050281298A1 "Analog External Cavity Laser" is designed to directly apply the Bragg grating to the other end of the laser source with only one collimating lens in the middle and no other metal structure. Although this design can reduce the laser volume, it cannot adjust the length of the laser outer cavity. The wavelength is adjusted by changing the temperature of the Bragg grating, but the wavelength adjustment speed is quite slow. In summary, whether the design of the scratched metal structure or the electric motor rotating interference film or the Bragg grating external cavity laser system can achieve the purpose of laser wavelength adjustment, the design is complicated. The overall size of the laser system is too large, which is less than the requirement of light weight and simple cost. [New content] In view of the convenience of reducing the external cavity laser system and avoiding the use of bulky flexible metal structures to simplify the design and reduce the cost, the author conceived to replace the flexible metal structure with a spring element. A grating is placed in front of the 矽 spring element and two small piezoelectric actuators are mounted on the back side to simultaneously achieve the length and wavelength adjustment of the laser outer cavity. The device is characterized in that after driving the piezoelectric actuator, the neon spring element generates a relative displacement to the laser source end according to the magnitude of the voltage input to the piezoelectric actuator to change the length of the laser outer cavity. The grating is mounted on the front of the Shihite 5 M400149 element. Therefore, when the spring element is displaced by the piezoelectric actuation, the grating will also have a relative displacement to the laser source. Therefore, the distance from the laser source to the optical handle, that is, the optical resonance_length change, the wavelength of Leixian will also change the length of the optical cavity of the county to change to achieve the laser wavelength. Therefore, the size of the spring constant of the Nasa sauce component will be expected to affect the size of the laser wavelength adjustment, which can be influenced by the geometry and size of the spring element. Achieve the appropriate adjustment range for the required wavelength. As described above (4), the main purpose of the spring element device is to replace the metal structure in the external cavity laser system with a spring element, thereby reducing the overall volume of the outer cavity laser. Providing users with the need to consider the size and weight of the small external cavity laser system to increase the convenience and portability of use. The other purpose of this creation is that the Shixi spring element is produced in batches using a semiconductor process, and dozens of reed elements can be fabricated simultaneously on the same Shihua wafer, and the dimensional accuracy can be controlled to a certain extent. No additional processing is required to achieve the convenience of mass production. Another purpose of this creation is that the mass production cost and the raw material price of the spring element are much lower than that of the metal structure, so as to save the cost of the external cavity laser system. [Embodiment] In order to explain the principle and design of the present invention, the following specific embodiments are described. Figure 1 shows the overall architecture of the present embodiment. In the left half of the laser system, the laser diode (100) of the laser diode is equipped with a laser diode (4〇1) and a laser diode power connector (402), and the laser diode (401) The front end is fixed by the laser diode holder (2〇1). In the middle part of the laser system 6 M400149 The cymbal consists of a collimating lens holder consisting of a collimating lens holder (3〇1) and a collimating lens (302). (3〇1) can be moved along the laser outer cavity (2G2) in the laser outer cavity (2〇2) until the laser beam is collimated by the collimating lens (3()2). In the right half of the laser system, a spring element (6〇1) is mounted on the heat-dissipating copper block (1〇1) of the spring element, and a grating is arranged on the front side of the spring element (6〇1). 501) The grating mounting portion (502) on the 矽 spring element is shown in FIG. 2, and on the reverse side of the 矽 spring element (6〇1), there are two piezoelectric actuators (7〇la) on the upper and lower sides ( 701b) On the piezoelectric actuator on the 矽 spring element • The lower side mounting (702a) (7〇2b). On the other side of the two piezoelectric actuators (7〇1), the front side of the heat-dissipating copper block (101) of the device is shown in Fig. 1. After the collimating lens holder (301) is positioned, that is, after the laser beam is collimated, the laser beam is then returned to the laser beam using the moving laser outer cavity (202) in the radial direction of the laser outer cavity (2〇2). The laser diode (4〇1) is finally assembled with the left, middle and right halves of the laser system. The feature of this creation is that the design of the spring element (601) is shown in Figure 3. The upper and lower side mounting positions of the two piezoelectric actuators are designed on the reverse side of the stone spring element (6〇1). 2a) Φ (702b), a laser light penetration (6〇3) is designed in the middle of the 矽 spring element (601). The main design capable of deforming the 矽 spring element (601) is its front and back groove design (602a) (602b), wherein the front groove (602a) of the 矽 spring element (601) is partially enlarged, as shown in FIG. Shown. When the voltage is input to the piezoelectric actuator (701a) (701b), the piezoelectric actuator (7〇ia) (701b) will forward correspondingly push and deform according to the magnitude of the input voltage, because The strength of the heat sink copper block (101) of the Shixi spring element is much greater than that of the spring element (601), so that the spring element (601) is deformed by the piezoelectric actuator (701a) (701b). In addition to this, the grating (501) is displaced toward the laser diode (401) end by the 矽 spring element 7 M400149 (601) because it is mounted on the front side of the 矽 spring element (601). In this way, the length of the laser cavity, that is, the distance from the laser diode (401) to the grating (501), will be changed accordingly to achieve the purpose of wavelength adjustment. [Simplified illustration] FIG. Overall architecture diagram Figure 2 Front view of the spring element of the embodiment

FIG. 3 is a reverse view of the spring element of the embodiment. FIG. 4 is a partial enlarged view of the front surface of the spring element. FIG. 5 is a schematic cross-sectional view of the right half of the laser system. [Main component symbol description] (100) Laser diode heat dissipation Copper block (201) laser diode holder (301) collimator lens holder (401) laser diode (501) grating (6〇1) 矽 spring element (101) 矽 spring element heat sink copper block ( 202) Laser external cavity (302) collimating lens (402) laser diode power connector (502) 矽 spring element on grating mounting (6〇2a) 矽 spring element front groove (603) 矽 spring element Upper laser light penetration (602b) concave groove of the elastic element (701a) upper piezoelectric actuator (7〇1b) lower piezoelectric actuator (702a), spring element upper piezoelectric actuator Upper side mounting (702b) 矽 Spring element on the lower side of the piezoelectric actuator 8

Claims (1)

Patent application scope: A small external cavity laser system that uses a spring element to adjust the wavelength. The device is a laser diode with a left half and a laser diode with a laser diode. Wrapped, and then with the right half of the grating, the spring element and the heat-dissipating metal block of the device, the middle laser tube and the internal collimator lens are clamped to form a tight and stable external cavity. The radiation system is characterized in that the neon spring element generates a relative shape variable due to the pushing of the piezoelectric actuator, thereby changing the wavelength of the laser light. 2. A small external cavity laser system for adjusting the wavelength by using a 矽 spring element as described in the scope of the patent application, wherein a 矽 spring element having a wavelength adjustment function is disposed at one end of the laser outer cavity and connected to the heat dissipation thereof On the metal block, the device comprises a laser beam penetrating window, two sets of piezoelectric actuator mounting positions and two grooves on each of the front and back surfaces, wherein the input voltage is after the piezoelectric actuator, The piezoelectric actuator generates a relative pushing force according to the magnitude of the input voltage to drive the 矽 spring element to produce a forward deformation. 3. For the small external cavity laser system using the 矽 spring element to adjust the wavelength as described in the first paragraph of the patent application, the optical feedback mechanism is sought, and the collimator lens holder is positioned in the axial direction of the laser outer cavity. Thereafter, after the laser beam is collimated, the diffracted laser beam generated on the grating can be returned to the laser diode by adjusting the movement of the outer tube of the laser in its radial direction.