Low-cost and low-power wavelength-tunable laser

Abstract

The present invention relates to a wavelength tunable laser with low cost and low power consumption, which comprises a mirror, an optical etalon, a phase controller, an aspheric lens A, a laser chip, an aspheric lens B, an optical isolator, a focusing lens, and an optical fiber arranged in sequence from left to right; the laser chip is an SLD chip, and antireflection optical films and partial reflection optical films are respectively coated on the left and right end faces of the laser chip, and the partial reflection optical film on the end face far from the mirror and the mirror form a resonant cavity of the laser; the aspheric lens A and the aspheric lens B are used for shaping a beam with a large divergence angle into a parallel light with a small divergence angle; the optical etalon is used for wavelength selection, and two optically parallel flat plates are spaced apart, the optically parallel flat plates are perpendicular or at a certain angle to the optical axis of the laser, the thicknesses of the two optically parallel flat plates are different, and high-reflection optical films are coated on the left and right side surfaces of the optically parallel flat plates; a resistor containing an electrode is lithographed on the surface of the optically parallel flat plate.

Description

Technical Field

[0001] The present invention relates to a wavelength tunable laser with low cost and low power consumption. Background Art

[0002] A semiconductor laser, also known as a laser diode, is a laser using semiconductor material as the working substance. It is the most practical and important type of laser. It has a small volume, a long lifespan, and can be pumped by a simple injection current method. Its working voltage and current are compatible with integrated circuits, so it can be monolithically integrated with them. Moreover, it can directly perform current modulation at a frequency up to GHz to obtain a high-speed modulated laser output. Due to these advantages, semiconductor diode lasers have been widely used in laser communication, optical storage, optical gyroscopes, laser printing, ranging, radar, and other fields.

[0003] Existing semiconductor lasers usually have non-tunable wavelengths, while lasers with wavelength tunable functions have problems such as complex structures, difficult assembly, and high costs. At the same time, existing semiconductor lasers have high power consumption. Summary of the Invention

[0004] The object of the present invention is to provide a wavelength tunable laser with low cost and low power consumption for the above deficiencies.

[0005] The solution adopted by the present invention to solve the technical problem is that a wavelength tunable laser with low cost and low power consumption includes a reflecting mirror, an optical etalon, a phase controller, an aspheric lens A, a laser chip, an aspheric lens B, an optical isolator, a converging lens, and an optical fiber arranged in sequence from left to right;

[0006] The laser chip is an SLD chip. Anti-reflection optical films and partial reflection optical films are respectively coated on the left and right end faces of the laser chip. The partial reflection optical film on the end face far from the reflecting mirror and the reflecting mirror form the resonant cavity of the laser;

[0007] The aspheric lens A and the aspheric lens B are used to shape a beam with a large divergence angle into a parallel light with a small divergence angle;

[0008] The optical etalon is used for wavelength selection. Two optically parallel flat plates are placed at intervals. The optically parallel flat plates are perpendicular or non-perpendicular to the optical axis of the laser. The two optically parallel flat plates have different thicknesses. High-reflection optical films are coated on the left and right side surfaces of the optically parallel flat plates, and only light with a specific interval of wavelengths can pass through with a small loss;

[0009] A resistor with an electrode is lithographed on the surface of the optically parallel flat plate;

[0010] Optical anti-reflection films are coated on the light-passing surfaces on both sides of the phase controller. A resistor with an electrode is lithographed on the phase controller;

[0011] The resistors on the optical parallel flat sheet and the phase controller are externally connected to a power supply to load current.

[0012] The converging lens is used to converge the divergent, converging or collimated light beam to a specific position.

[0013] Furthermore, antireflection optical films are coated on both light-transmitting surfaces of the aspherical lens A and the aspherical lens B.

[0014] Furthermore, optical antireflection films are coated on both the left and right end faces of the converging lens.

[0015] Furthermore, the optical fiber is a polarization-maintaining or non-polarization-maintaining single-mode optical fiber line.

[0016] Furthermore, the mirror reflects light by utilizing the characteristic that the medium itself has a high reflectivity to light, or a high-reflection optical film is coated on the surface of the medium.

[0017] Furthermore, the laser chip is arranged on the cold surface of the semiconductor thermoelectric cooler. A high-thermal-conductivity bracket is arranged on the hot surface of the semiconductor thermoelectric cooler. The high-thermal-conductivity bracket is installed on the heat-conducting base. The optical etalon is assembled inside the heat-conducting base. Circuits connecting the laser chip, the semiconductor thermoelectric cooler, and the optical etalon are respectively arranged on the heat-conducting base. The circuits are connected to the external circuit through metal pins arranged on the heat-conducting base.

[0018] Furthermore, the heat-conducting base is installed inside the outer housing.

[0019] Compared with the prior art, the present invention has the following beneficial effects: adjustable wavelength, low loss of the laser, high output optical power, stable wavelength, low noise, and compact structure, easy production and processing of materials, simple assembly, low cost, and easy mass production. Description of the Drawings

[0020] The following further describes the present invention in combination with the drawings.

[0021] Figure 1 It is a structural schematic diagram of the present laser.

[0022] Figure 2 It is a heat dissipation structure diagram of the present laser.

[0023] Figure 3 It is a structural schematic diagram of the outer housing.

[0024] In the figure: 1 - mirror, 2 - optical etalon, 3 - phase controller, 4 - aspherical lens A, 5 - laser, 6 - chip, 6 - aspherical lens B, 7 - optical isolator, 8 - focusing lens, 9 - optical fiber; 10 - semiconductor thermoelectric cooler; 11 - high thermal conductivity bracket; 12 - heat conducting base; 13 - metal pin; 14 - outer housing; 15 - base; 16 - light transmissive sheet; 17 - structural member. Detailed implementation mode

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0026] As Figures 1-3 shown, a wavelength tunable laser with low cost and low power consumption includes a mirror 1, an optical etalon 2, a phase controller 3, an aspherical lens A 4, a laser chip 5, an aspherical lens B 6, an optical isolator 7, a focusing lens 8, and an optical fiber 9 arranged in sequence from left to right;

[0027] The laser chip is an SLD chip. Anti-reflection optical films and partial reflection optical films are respectively coated on the left and right end faces of the laser chip. The partial reflection optical film on the end face far from the mirror and the mirror form the resonant cavity of the laser;

[0028] The aspherical lens A and the aspherical lens B are made of a light transmissive material as the base material, and are used to shape the light beam with a large divergence angle into a parallel light with a small divergence angle. Utilizing the reversibility of light and combining with the mirror can ensure that the light beam has a small intracavity loss in the resonant cavity;

[0029] The optical etalon is used for wavelength selection. Two optically parallel flat plates are placed at a certain interval. The optically parallel flat plates are perpendicular to the optical axis of the laser or form a certain angle with the optical axis. The two optically parallel flat plates have different thicknesses. High reflection optical films are coated on both the left and right sides of the optically parallel flat plates. Only light with a wavelength within a specific interval can pass through with a small loss, and the loss of the remaining wavelengths is large. When two optically parallel flat plates with different thicknesses are stacked and used, due to the vernier effect, only light with one wavelength within a specific wavelength range can pass through with a small loss, and the loss of all other wavelengths is large. They achieve the function of selecting a single wavelength within the required working range;

[0030] Only light with a wavelength within a specific interval can pass through with a small loss;

[0031] The surface of the optically parallel flat plate is lithographed with a resistor containing an electrode. By changing the current applied to the electrode, the temperature of the etalon can be changed, and then the equivalent optical length of the etalon can be changed to achieve the function of wavelength tunability;

[0032] The phase controller uses a high-transmittance optical material with a relatively large refractive index as the substrate. Optical antireflection films are coated on the light-transmitting surfaces on both the left and right sides thereof. A resistor containing an electrode is lithographed on the phase controller. By changing the current of the resistor, its optical length can be changed, and thus the external cavity length of the laser can be accurately controlled.

[0033] The resistor on the optical parallel flat plate and the phase controller are both externally connected to a power supply to load current.

[0034] The converging lens uses an optical material with a relatively high transmittance as the substrate. Its surface is processed into a spherical surface or an aspherical surface to converge a divergent, converging or collimated light beam to a specific position.

[0035] The optical isolator has a direction-selective effect on the passage of light. It only allows light to pass through in a specific direction, and cuts off the light propagating in the reverse direction. It is placed in the light output optical path of the laser, and the placement direction is consistent with the light output direction of the laser to avoid external light from returning and injecting into the resonant cavity of the laser, disturbing the resonance stability of the laser. The optical isolator can optimize the line width and relative intensity noise of the laser.

[0036] During use:

[0037] When a current is injected into the wide emission spectrum chip SLD, that is, carriers are injected, the population inversion of atoms in the active layer occurs, and electrons are excited from the valence band with lower energy to the conduction band with higher energy. When the applied current is greater than the threshold current, the number of electrons in the high-energy state is much larger than the number of holes in the low-energy state. A large number of electrons and holes in the population inversion state randomly recombine, and the laser chip is in the spontaneous emission state, emitting photons. The emitted photons move along the waveguide, and will re-excite the recombination of electrons and holes to form stimulated photons. The self-emitted photons and the stimulated photons are both amplified along the waveguide to form amplified spontaneous emission, and the light exits from the two end faces of the chip.

[0038] After the light with a wide radiation spectrum passes through the optical etalon, the light with a single wavelength having the smallest loss is most likely to reach the state of gain and loss balance. Due to the mode competition of the laser, the gain of light with other wavelengths will be less than the loss, and the light emission is suppressed. The light with the wavelength having the smallest loss resonates and amplifies back and forth in the resonant cavity, forming the laser of a specific single longitudinal mode lasing by the laser; a part of the light passes through the partial reflection film of the SLD chip and exits the laser resonant cavity, and thus the narrow line width laser radiated outside the cavity is obtained.

[0039] The light of the above laser passes through the aspherical lens and is shaped into parallel light with a relatively large Rayleigh range. After passing through the isolator for optical reverse isolation, it can be used as an independent spatial light source, or this spatially collimated light can be converged into an optical fiber line through a converging lens, which is convenient for directly accessing the optical fiber network.

[0040] In this embodiment, antireflection optical films are coated on both light-transmitting surfaces of the aspherical lens A and the aspherical lens B.

[0041] In this embodiment, optical antireflection films are coated on both the left and right end faces of the converging lens.

[0042] In this embodiment, the optical fiber is a polarization-maintaining or non-polarization-maintaining single-mode optical fiber line, which generally consists of a core, a cladding, a coating layer or a sheath. Accessories can also be added outside it to make the assembly more convenient. For example, a capillary is added to form an optical fiber head.

[0043] In this embodiment, the mirror reflects light by utilizing the characteristic that the medium itself has a high reflectivity to light, or a high-reflection optical film is coated on the surface of the medium, so that the light reaching it is reflected back according to the law of reflection, and the loss is minimized as much as possible.

[0044] In this embodiment, the SLD is used as an electro-optic chip. Most of its energy is converted into heat, and a semiconductor thermoelectric cooler (TEC) is required to conduct the heat away. The laser chip is arranged on the cold surface of the semiconductor thermoelectric cooler 10. A high thermal conductivity bracket 11 is arranged on the hot surface of the semiconductor thermoelectric cooler, and the high thermal conductivity bracket is installed on the heat-conducting base 12. Most of the heat generated by the SLD is conducted through the TEC, the bracket and the base. The EC also generates heat while transferring the heat energy of the SLD, and the heat is conducted through the bracket and the base. The optical etalon is assembled inside the heat-conducting base. The heat generated by the SLD and the TEC will directly affect the etalon. Even if no current is applied to the etalon, its reference temperature will be higher than the ambient temperature under steady state. The greater the temperature difference between the etalon and the external environment, the more stable the thermal control of the etalon. Such a mechanical design can ensure that when the laser is at the same temperature stability, the energy consumed by the etalon is the least. That is, the design of the TEC for controlling the temperature of the SLD, combined with the unique mechanical design, makes the reference temperature provided by the hot surface temperature of the TEC to the etalon, so that the total energy consumption of the laser is much less than that of the external cavity lasers on the market; Circuits connecting the laser chip, the semiconductor thermoelectric cooler and the optical etalon are respectively arranged on the heat-conducting base. The circuit is connected to the external circuit through a metal Pin 13 arranged on the heat-conducting base to realize the electrical control of the laser.

[0045] In this embodiment, the heat-conducting base is installed inside the outer housing 14. A light-transmitting hole is provided at the right end of the outer housing, and the light-transmitting hole is sealed with a light-transmitting sheet 16 having a high transmittance. The outer housing is welded to the base 15 to form a sealed cavity required for the laser chip. The spatially collimated light of the laser will come out from the light-transmitting sheet. A reflecting mirror, an optical etalon, a phase controller, an aspherical lens A, a laser chip, an aspherical lens B, and an optical isolator are all arranged inside the outer housing. The focusing lens and the optical fiber are installed on the right side of the outer housing alone or through a structural member 17 by bonding or welding. The materials required for this structure are simple, the processing difficulty is low, the cost is low, the assembly is simple, the yield is high, and the total cost is much lower than that of other designs.

[0046] This laser is an external cavity semiconductor laser. The vernier effect of two etalons in the external cavity is used to achieve wavelength tunability. The external cavity structure can achieve a narrow linewidth of the laser <100KHz. In the optical path, the beam shaping of the aspherical lens is used to make the laser have low loss and high output power. The TEC independently dissipates heat for the SLD, and its heat can improve the reference temperature of the etalon through medium conduction. The laser not only has low energy consumption, but also has stable wavelength and low noise. This laser has outstanding advantages in terms of output power, wavelength stability, linewidth, and power consumption, and has a compact structure, easy production and processing of materials, simple assembly, low cost, and is easy to mass-produce.

[0047] If this patent discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (such as using bolts or screws), or it can also be understood as: a non-detachable fixed connection (such as riveting, welding). Of course, the mutual fixed connection can also be replaced by an integral structure (such as manufactured by integral forming using a casting process) (except where it is obviously impossible to use the integral forming process).

[0048] In the description of this patent, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this patent, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to this patent.

[0049] The above-mentioned preferred embodiments have further detailed the purpose, technical solution, and advantages of the present invention. It should be understood that the above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A wavelength tunable laser with low cost and low power consumption, characterized in that: It includes a reflector, an optical etalon, a phase controller, an aspherical lens A, a laser chip, an aspherical lens B, an optical isolator, a focusing lens, and an optical fiber, which are arranged in sequence from left to right. The laser chip is an SLD chip. Anti-reflection optical films and partial reflection optical films are respectively coated on the left and right end faces of the laser chip. The partial reflection optical film on the end face far from the reflector and the reflector form the resonant cavity of the laser. The aspherical lens A and the aspherical lens B are used to shape the beam with a large divergence angle into a parallel light with a small divergence angle. Anti-reflection optical films are coated on both light-passing surfaces of the aspherical lens A and the aspherical lens B. The optical etalon is used for wavelength selection. Two optical parallel flats are placed at intervals. The optical parallel flats are perpendicular or non-perpendicular to the optical axis of the laser. The two optical parallel flats have different thicknesses. High-reflection optical films are coated on the left and right side surfaces of the optical parallel flats, and only the light with a specific interval wavelength can pass through with a small loss. Resistors containing electrodes are lithographed on the surface of the optical parallel flat. The focusing lens is used to focus the divergent, convergent or collimated beam to a specific position. The laser chip is arranged on the cold surface of a semiconductor thermoelectric cooler. A high thermal conductivity bracket is arranged on the hot surface of the semiconductor thermoelectric cooler. The high thermal conductivity bracket is installed on a heat conduction base. The optical etalon is assembled inside the heat conduction base. Circuits connecting the laser chip, the semiconductor thermoelectric cooler, and the optical etalon are respectively arranged on the heat conduction base. The circuits are connected to the external circuit through metal pins arranged on the heat conduction base. The heat conduction base is installed inside the outer housing. Optical anti-reflection films are coated on the light-passing surfaces on both sides of the phase controller. Resistors containing electrodes are lithographed on the phase controller.

2. The wavelength tunable laser with low cost and low power consumption according to claim 1, wherein: Optical anti-reflection films are coated on both the left and right end faces of the focusing lens.

3. The wavelength tunable laser with low cost and low power consumption according to claim 1, wherein: The optical fiber is a polarization-maintaining or non-polarization-maintaining single-mode optical fiber line.

4. The wavelength tunable laser with low cost and low power consumption according to claim 1, wherein: The reflector uses the characteristic that the medium itself has a high reflectivity to light for reflection, or a high-reflection optical film is coated on the surface of the medium.

5. The wavelength tunable laser with low cost and low power consumption according to claim 1, characterized in that: The resistors on the optical parallel flat and the phase controller are externally connected to a power supply to load current.

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