Wide tuning laser

Abstract

The embodiment of the invention provides a wide tuning laser. The wide tuning laser comprises a first laser module, an outer cavity module and a second laser module which are connected in sequence, the end face, away from the outer cavity module, of the first laser module is provided with a first reflecting film, and the end face, away from the outer cavity module, of the second laser module is provided with a second reflecting film. The reflectivity of the first reflecting film is greater than that of the second reflecting film; the first laser module or the second laser module is used for generating an optical signal and injecting the optical signal into the outer cavity module; the outer cavity module is used for narrowing the line width of the optical signal, performing mode selection on the optical signal, and transmitting the optical signal meeting a preset mode to the second laser module or the first laser module; the optical signal meeting the preset mode reciprocates among the first reflecting film, the outer cavity module and the second reflecting film for multiple times to form laser oscillation, and the laser oscillation is output through the second reflecting film.

Description

Technical Field

[0001] The present disclosure relates to the field of lasers, and in particular to a wide-tuning laser. Background Art

[0002] A tunable laser is a laser that can continuously change the laser output wavelength within a certain range. This type of laser has a wide range of uses and can be used in spectroscopy, photochemistry, medicine, biology, integrated optics, pollution monitoring, semiconductor material processing, information processing and communications, etc. In particular, wavelength-tunable fiber lasers have great application value in wavelength division multiplexing systems, distributed fiber sensing systems, microwave photonic technology, etc., because of their compact structure, low cost, and good stability. Therefore, it is of great significance to achieve stable and tunable wavelength fiber laser output.

[0003] At present, the tunable range of tunable lasers is relatively small, which makes them unable to meet the needs of various application scenarios; and in order to broaden their tunable range, more devices need to be added, which leads to problems of high system complexity, high cost, and high loss, which has an adverse effect on the efficiency and stability of the laser.

[0004] Therefore, it is necessary to provide an improved technical solution to solve the problems existing in tunable lasers. Summary of the invention

[0005] In view of this, an embodiment of the present disclosure provides a widely tunable laser.

[0006] To achieve the above objectives, the technical solution of the present disclosure is implemented as follows:

[0007] The embodiment of the present disclosure provides a wide tunable laser, comprising a first laser module, an external cavity module, and a second laser module connected in sequence; the end face of the first laser module away from the external cavity module has a first reflective film, and the end face of the second laser module away from the external cavity module has a second reflective film; the reflectivity of the first reflective film is greater than the reflectivity of the second reflective film; the first laser module or the second laser module is used to generate an optical signal and inject it into the external cavity module; the external cavity module is used to narrow the line width of the optical signal and select a mode for the optical signal, and transmit the optical signal that meets the preset mode to the second laser module or the first laser module; the optical signal that meets the preset mode goes back and forth between the first reflective film, the external cavity module, and the second reflective film for multiple times to form laser oscillation, and is output through the second reflective film.

[0008] In some embodiments, the first laser module is used to generate an optical signal having a first tunable wavelength band, and the second laser module is used to generate an optical signal having a second tunable wavelength band, wherein the first tunable wavelength band is different from the second tunable wavelength band.

[0009] In some embodiments, a reflection band of the first reflection film at least covers the first tunable band and the second tunable band, and a reflection band of the second reflection film at least covers the first tunable band and the second tunable band.

[0010] In some embodiments, the external cavity module includes at least three waveguides arranged along a first direction, and an extension direction of the waveguides intersects with the first direction; a micro-ring is arranged between any two adjacent waveguides of the at least three waveguides.

[0011] In some embodiments, the free optical spectrum of each of the microrings is different.

[0012] In some embodiments, a first modulation unit is disposed on the first waveguide and the last waveguide, and the first modulation unit is a phase modulator.

[0013] In some embodiments, a second modulation unit is disposed on at least one of the micro-rings, and the second modulation unit is a thermal modulator or an electro-optical modulator.

[0014] In some embodiments, the microring is a racetrack-type microring, and a straight waveguide portion of the racetrack-type microring is coupled with two adjacent waveguides.

[0015] In some embodiments, the end surface of the first laser module connected to the external cavity module has a first anti-reflection film, and the end surface of the second laser module connected to the external cavity module has a second anti-reflection film.

[0016] In some embodiments, the wide-tunable laser further includes: a first coupling unit connected between the first laser module and the first end of the external cavity module, the first coupling unit being used to couple the optical signal output by the first laser module to the first end of the external cavity module, or to couple the optical signal output by the first end of the external cavity module to the first laser module; a second coupling unit connected between the second laser module and the second end of the external cavity module, the second coupling unit being used to couple the optical signal output by the second laser module to the second end of the external cavity module, or to couple the optical signal output by the second end of the external cavity module to the second laser module; the first end and the second end of the external cavity module are two opposite end faces of the external cavity module.

[0017] The embodiment of the present disclosure provides a wide tunable laser, comprising a first laser module, an external cavity module, and a second laser module connected in sequence; the end face of the first laser module away from the external cavity module has a first reflective film, and the end face of the second laser module away from the external cavity module has a second reflective film; the reflectivity of the first reflective film is greater than the reflectivity of the second reflective film; the first laser module or the second laser module is used to generate an optical signal and inject it into the external cavity module; the external cavity module is used to narrow the line width of the optical signal and select a mode for the optical signal, and transmit the optical signal that meets the preset mode to the second laser module or the first laser module; the optical signal that meets the preset mode goes back and forth between the first reflective film, the external cavity module, and the second reflective film for multiple times to form laser oscillation, and is output through the second reflective film. The embodiment of the present disclosure integrates the first laser module, the external cavity module, and the second laser module, and uses the first laser module or the second laser module to generate different optical signals and tune the optical signals in different scenarios, so that the tunable range of the laser provided by the embodiment of the present disclosure can fully cover the tuning range of the first laser module and the tuning range of the second laser module, thereby achieving the expansion of the laser tuning range; and the optical signal generated by the first laser module or the optical signal generated by the second laser module can be tuned in different scenarios, so the laser will not be affected by the expansion of the tuning range. The laser provided by the embodiment of the present disclosure can also form a single-mode laser oscillation between the first reflective film, the external cavity module, and the second reflective film through the optical signal, and is enhanced by the first laser module or the second laser module during the oscillation process, so that a high-power, narrow-linewidth single-mode laser can be output. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of a wide tunable laser provided in an embodiment of the present disclosure Figure 1 ;

[0019] Figure 2 for Figure 1 Schematic diagram of the resonance spectrum of the external cavity module shown;

[0020] Figure 3 A schematic diagram of the structure of a wide tunable laser provided in an embodiment of the present disclosure Figure 2 ;

[0021] Figure 4 A schematic diagram of the structure of a micro-ring provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present disclosure and the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0023] In the following description, a large number of specific details are given to provide a more thorough understanding of the present disclosure. However, it is obvious to those skilled in the art that the present disclosure can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present disclosure, some technical features known in the art are not described; that is, all features of actual embodiments are not described here, and well-known functions and structures are not described in detail.

[0024] In the drawings, the sizes of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0025] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not indicate that the present disclosure necessarily has the first element, component, region, layer or part.

[0026] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be a limitation of the present disclosure. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0027] In order to thoroughly understand the present disclosure, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present disclosure. The preferred embodiments of the present disclosure are described in detail below, but in addition to these detailed descriptions, the present disclosure may also have other implementations.

[0028] It should be noted that, for the convenience of description, various directions that may be used in the following description are first defined. The extension direction of the waveguide in the external cavity module is defined as the X direction, and the arrangement direction of the waveguide in the external cavity module is defined as the Y direction (first direction), wherein the X direction and the Y direction may be perpendicular to each other.

[0029] Figure 1 A schematic diagram of the structure of a wide tunable laser provided in an embodiment of the present disclosure Figure 1 . See Figure 1 The wide-tunable laser comprises a first laser module 10, an external cavity module 20 and a second laser module 30 connected in sequence; the end face of the first laser module 10 away from the external cavity module 20 has a first reflection film 11, and the end face of the second laser module 30 away from the external cavity module 20 has a second reflection film 31; the reflectivity of the first reflection film 11 is greater than the reflectivity of the second reflection film 31; the first laser module 10 or the second laser module 30 is used to generate an optical signal and inject it into the external cavity module 20; the external cavity module 20 is used to narrow the line width of the optical signal and select the mode of the optical signal, and transmit the optical signal that meets the preset mode to the second laser module 30 or the first laser module 10; the optical signal that meets the preset mode goes back and forth between the first reflection film 11, the external cavity module 20 and the second reflection film 31 for multiple times to form laser oscillation, and is output through the second reflection film 31.

[0030] In some embodiments, the end face of the first laser module 10 having the first reflective film 11 is the first end face, and the end face where the first laser module 10 is connected to the external cavity module 20 is the second end face; the end face of the second laser module 30 having the second reflective film 31 is the third end face, and the end face where the second laser module 30 is connected to the external cavity module 20 is the fourth end face.

[0031] In some embodiments, current can be injected into the first laser module 10 to excite the gain medium in the first laser module 10 to generate an optical signal, and the optical signal is transmitted along the first optical path. The optical signal is injected into the first end 201 of the external cavity module 20 through the second end face of the first laser module 10, and the external cavity module 20 can resonate the part of the optical signal that meets the preset mode to enhance the optical signal that meets the preset mode, thereby achieving mode selection. It should be noted that the first end and the second end of the external cavity module are two opposite end faces of the external cavity module.

[0032] The external cavity module 20 also transmits the optical signal that meets the preset mode to the second laser module 30 through the second end 202. After that, the optical signal is reflected by the second reflective film 31 and then transmitted to the first laser module 10 along the second optical path, and is reflected by the first reflective film 11 and then transmitted to the second laser module 30 along the first optical path, so that the optical signal can go back and forth between the first reflective film 11, the external cavity module 20 and the second reflective film 31 for many times to form a single-mode laser oscillation, and the optical signal can be repeatedly enhanced by the gain medium in the first laser module 10 during the oscillation process, so that the laser can output a single-mode laser with high power and narrow line width from the end with lower reflectivity (the second reflective film 31). It should be noted that the first optical path is from the first reflective film to the first end of the external cavity module to the second end of the external cavity module to the second reflective film, and the second optical path is from the second reflective film to the second end of the external cavity module to the first end of the external cavity module to the first reflective film.

[0033] In other embodiments, current may be injected into the second laser module 30 to excite the gain medium in the second laser module 30 to generate an optical signal, and the optical signal is transmitted along the second optical path. The optical signal is injected into the second end 202 of the external cavity module 20 through the fourth end face of the second laser module 30, and the external cavity module 20 may resonate the part of the optical signal that meets the preset mode to enhance the optical signal that meets the preset mode, thereby achieving mode selection.

[0034] The external cavity module 20 also transmits the optical signal that meets the preset mode to the first laser module 10 through the first end 201. After that, the optical signal is reflected by the first reflective film 11 and transmitted to the second laser module 30 along the first optical path, and is reflected by the second reflective film 31 and transmitted to the first laser module 10 along the second optical path, so that the optical signal can go back and forth between the first reflective film 11, the external cavity module 20 and the second reflective film 31 for many times to form a single-mode laser oscillation, and the optical signal can be repeatedly enhanced by the gain medium in the second laser module 30 during the oscillation process, so that the laser can output a single-mode laser with high power and narrow line width from the end with lower reflectivity (the second reflective film 31).

[0035] In some embodiments, the reflectivity of the first reflective film 11 may be greater than or equal to 90%, and the reflectivity of the second reflective film 31 may be less than or equal to 10%.

[0036] In some embodiments, by integrating the first laser module, the external cavity module, and the second laser module, current is injected into the first laser module or the second laser module in different scenarios to generate different optical signals and tune the optical signals, so that the tunable range of the laser provided in the embodiment of the present disclosure can fully cover the tuning range of the first laser module and the tuning range of the second laser module, thereby widening the tuning range of the laser; and the optical signal generated by the first laser module or the optical signal generated by the second laser module can be tuned in different scenarios, so the laser will not be affected by the widening of the tuning range. Single-mode laser oscillation is formed between the first reflective film, the external cavity module, and the second reflective film by the optical signal, and is enhanced by the first laser module or the second laser module during the oscillation process, so that a high-power, narrow-linewidth single-mode laser can be output.

[0037] In some embodiments, the first laser module is used to generate an optical signal having a first tunable wavelength band, and the second laser module is used to generate an optical signal having a second tunable wavelength band, and the first tunable wavelength band is different from the second tunable wavelength band.

[0038] In some embodiments, the first laser module and the second laser module can generate an optical signal having a first tunable band and an optical signal having a second tunable band, respectively, so that the tunable range of the laser can be widened to the union of the first tunable band and the second tunable band, and during the tuning process, the optical signal generated by the first laser module or the optical signal generated by the second laser module can be tuned respectively, and the problems of low tuning accuracy, high tuning difficulty, and long tuning time will not be generated due to the widening of the tuning range. Therefore, the laser provided in the embodiment of the present disclosure has the characteristics of wide tuning, high accuracy, simple tuning, and short time consumption.

[0039] In a specific embodiment, the first laser module 10 is an S-band laser gain chip, so that the first laser module can generate an S-band optical signal; the second laser module 30 is a C+L-band laser gain chip, so that the second laser module 30 can generate a C+L-band optical signal. In this case, the tunable range of the laser provided in the embodiment of the present disclosure is the S+C+L band. It should be noted that the wavelength range of the S band is 1460nm to 1530nm, the wavelength range of the C band is 1530nm to 1565nm, and the wavelength range of the L band is 1565nm to 1625nm.

[0040] In some embodiments, the external cavity module includes at least three waveguides arranged along a first direction, and an extension direction of the waveguides intersects with the first direction; a micro-ring is arranged between any two adjacent waveguides among the at least three waveguides.

[0041] Figure 1 In the example, the outer cavity module 20 includes four waveguides arranged along the first direction. Figure 1 The external cavity module 20 includes four waveguides arranged along the Y direction, namely waveguide 211, waveguide 212, waveguide 213 and waveguide 214. A micro-ring 221 is arranged between waveguide 211 and waveguide 212, a micro-ring 222 is arranged between waveguide 212 and waveguide 213, and a micro-ring 223 is arranged between waveguide 213 and waveguide 214. It should be noted that the micro-ring in the present disclosure may be circular, racetrack-shaped or elliptical, and the present disclosure does not impose any limitation on this.

[0042] In some embodiments, the coupling coefficient between the microring and the waveguide can be around 0.15 to ensure the transmission efficiency of the optical signal in the external cavity module, and the Q value (quality factor) of the microring can reach the order of 1E5 or above to improve the sensitivity of the external cavity module.

[0043] In some embodiments, the optical signal can be transmitted along the first optical path in the external cavity module 20: coupled from the waveguide 211 to the microring 221 and resonated in the microring 221, coupled from the microring 221 to the waveguide 212, coupled from the waveguide 212 to the microring 222 and resonated in the microring 222, coupled from the microring 222 to the waveguide 213, coupled from the waveguide 213 to the microring 223 and resonated in the microring 223, and coupled from the microring 223 to the waveguide 214.

[0044] In some embodiments, the optical signal can be transmitted along the second optical path in the external cavity module 20: coupled from the waveguide 214 to the microring 223 and resonated in the microring 223, coupled from the microring 223 to the waveguide 213, coupled from the waveguide 213 to the microring 222 and resonated in the microring 222, coupled from the microring 222 to the waveguide 212, coupled from the waveguide 212 to the microring 221 and resonated in the microring 221, and coupled from the microring 221 to the waveguide 211.

[0045] In some embodiments, the mode selection wavelength of the external cavity module can be adjusted to a preset mode by adjusting the resonant wavelength of each micro-ring in the external cavity module.

[0046] It should be noted that the number of waveguides in the external cavity module is one more than the number of microrings, and the embodiment of the present disclosure does not impose any other restrictions on the number of waveguides and the number of microrings in the external cavity module.

[0047] In some embodiments, the free optical spectrum of each micro-ring is different.

[0048] In some embodiments, the circumference of the micro-rings can be designed so that each micro-ring has a different free spectral range (FSR).

[0049] In some embodiments, when the difference between the free optical spectrum of at least two micro-rings in the external cavity module is small, the external cavity module can have a larger range of equivalent free optical spectrum. By increasing the number of micro-rings in the external cavity module, not only the free optical spectrum of the external cavity module can be increased, but also the side mode suppression ratio (Side Mode Suppression Ratio, SMSR) of the external cavity module 20 can be effectively improved, which helps to improve the stability of the single-mode laser output by the laser.

[0050] In some embodiments, the external cavity module includes at least four waveguides arranged along the Y direction, and the external cavity module may include at least three microrings. By designing the parameters of at least three microrings, the free spectrum path difference of at least two microrings is less than or equal to a first preset value and greater than zero. The value range of the first preset value can be set according to demand, for example, 0.4nm, 0.6nm, 0.8nm or 1.0nm. In this way, the external cavity module can have the characteristics of a large tuning range, a high side mode suppression ratio and good stability.

[0051] Figure 2 for Figure 1 Schematic diagram of the resonance spectrum of the external cavity module shown. Figure 2 , in a specific example, Figure 1 The free spectral ranges of microring 221, microring 222 and microring 223 are 1.567 nm, 1.912 nm and 1.554 nm respectively. In this case, the free spectral ranges of the three microrings are slightly different (the difference is less than 0.4 nm). At this time, the free spectral range of the external cavity module 20 can reach Figure 2 The 225 nm shown enables the external cavity module 20 to have a large free tuning range, while having good tuning accuracy and side mode suppression ratio and good stability.

[0052] In some embodiments, a first modulation unit is disposed on the first waveguide and the last waveguide, and the first modulation unit is a phase modulator.

[0053] Figure 3 A schematic diagram of the structure of a wide tunable laser provided in an embodiment of the present disclosure Figure 2 . See Figure 3 In the external cavity module 20 , a first modulation unit 231 is disposed on the waveguide 211 , and a first modulation unit 232 is disposed on the waveguide 214 .

[0054] When the first laser module 10 is used to inject an optical signal into the external cavity module 20, the first end 201 can be regarded as the input end of the external cavity module 20. By changing the voltage intensity applied to the first modulation unit 231 and adjusting the modulation parameters of the first modulation unit 231, the phase of the optical signal entering the external cavity module 20 can be effectively controlled, thereby adjusting the wavelength of the laser output by the laser and ensuring the wide range tuning capability of the laser.

[0055] When the second laser module 30 is used to inject an optical signal into the external cavity module 20, the second end 202 can be regarded as the input end of the external cavity module 20. By changing the voltage intensity applied to the first modulation unit 232 and adjusting the modulation parameters of the first modulation unit 232, the phase of the optical signal entering the external cavity module 20 can be effectively controlled, thereby adjusting the wavelength of the laser output by the laser and ensuring the wide range tuning capability of the laser.

[0056] In some embodiments, a second modulation unit is disposed on at least one micro-ring, and the second modulation unit is a thermal modulator or an electro-optical modulator.

[0057] See also Figure 3 The microring 221, the microring 222 and the microring 223 are respectively provided with a second modulation unit 241, a second modulation unit 242 and a second modulation unit 243.

[0058] In the case where the second modulation unit is a thermal modulator (e.g., a hot electrode), the temperature of the corresponding microring is changed by adjusting the voltage on the second modulation unit. The change in the temperature of the microring will cause the change in the refractive index of the microring, thereby changing the resonant wavelength of the microring. In this way, the resonant wavelength of the microring can be changed by using the second modulation unit, thereby adjusting the mode selection wavelength of the external cavity module, and realizing the tunable output laser of the laser.

[0059] When the second modulation unit is an electro-optic modulator, the refractive index of the second modulation unit itself is changed by adjusting the electric field applied to the second modulation unit, thereby affecting the effective refractive index of the microring, thereby changing the resonant wavelength of the microring.

[0060] In some embodiments, the output laser of the laser can be tuned by adjusting the modulation parameters of the first modulation unit 231 or the first modulation unit 232 and adjusting the control parameters (voltage or electric field) of the second modulation unit on the microring to jointly adjust the mode selection wavelength of the external cavity module 20.

[0061] In some embodiments, see Figure 3The wide-tunable laser also includes: a first coupling unit 41, connected between the first laser module 10 and the first end 201 of the external cavity module 20, the first coupling unit 41 is used to couple the optical signal output by the first laser module 10 to the first end 201 of the external cavity module 20, or to couple the optical signal output by the first end 201 of the external cavity module 20 to the first laser module 10; a second coupling unit 42, connected between the second laser module 30 and the second end 202 of the external cavity module 20, the second coupling unit 42 is used to couple the optical signal output by the second laser module 30 to the second end 202 of the external cavity module 20, or to couple the optical signal output by the second end 202 of the external cavity module 20 to the second laser module 30; the first end 201 and the second end 202 of the external cavity module 20 are two opposite end faces of the external cavity module 20.

[0062] See also Figure 3 , the first coupling unit 41 and the second coupling unit 42 can be a mode spot converter. The first coupling unit 41 is used to adjust the spot size of the optical signal to match the mode spot size between the second end face of the first laser module 10 and the first end 201 of the external cavity module 20, improve the coupling efficiency between the first laser module 10 and the first end 201 of the external cavity module 20, and avoid unnecessary loss of the optical signal during transmission. The second coupling unit 42 is used to adjust the spot size of the optical signal to match the mode spot size between the second end face of the second laser module 30 and the second end 202 of the external cavity module 20, improve the coupling efficiency between the second laser module 30 and the second end 202 of the external cavity module 20, and avoid unnecessary loss of the optical signal during transmission.

[0063] In some embodiments, the reflection band of the first reflection film covers at least the first tunable band and the second tunable band, and the reflection band of the second reflection film covers at least the first tunable band and the second tunable band.

[0064] In some embodiments, the reflection band of the first reflection film and the reflection band of the second reflection film can fully cover the first tunable band and the second tunable band to avoid the loss of the laser tuning range due to the inability to effectively reflect the optical signal of some bands. In a specific example, the first laser module is an S-band laser gain chip, and the second laser module is a C+L-band laser gain chip, then the reflection band of the first reflection film and the reflection band of the second reflection film can be the S+C+L band.

[0065] In some embodiments, see Figure 3 The end surface of the first laser module 10 close to the external cavity module 20 has a first anti-reflection film 12 , and the end surface of the second laser module 30 close to the external cavity module 20 has a second anti-reflection film 32 .

[0066] In some embodiments, the second end surface of the first laser module 10 is coated with a first anti-reflection film 12, which helps to reduce the light loss inside the first laser module 10 and improve the transmission efficiency of the output signal of the first laser module 10. The second end surface of the second laser module 30 is coated with a second anti-reflection film 32, which helps to reduce the light loss inside the second laser module 30 and improve the transmission efficiency of the output signal of the second laser module 30.

[0067] In some embodiments, the anti-reflection band of the first anti-reflection film and the anti-reflection band of the second anti-reflection film can fully cover the first tunable band and the second tunable band to avoid the loss of the laser tuning range caused by the inability of optical signals in some bands to effectively pass through the first anti-reflection film or the second anti-reflection film.

[0068] In some embodiments, the microring is a racetrack-type microring, and a straight waveguide portion of the racetrack-type microring is coupled to two adjacent waveguides.

[0069] Figure 4 A schematic diagram of the structure of a micro-ring provided in an embodiment of the present disclosure. Figure 4 The microring shown is a racetrack type microring, see Figure 4 , the microring can be regarded as consisting of two straight waveguide parts p1 and p2 and two curved waveguide parts p3 and p4. Specifically, the straight waveguide parts p1 and p2 can be coupled to different waveguides respectively, and a second modulation unit can be provided on the curved waveguide part p3 or p4. In this way, the coupling area of ​​the microring and the waveguide can be increased, thereby improving the coupling coefficient and coupling efficiency. It should be noted that the microring in the embodiment of the present disclosure can be approximately regarded as consisting of a straight waveguide part and a curved waveguide part, which is not used to limit the microring to be formed by splicing a straight waveguide part and a curved waveguide part. In fact, the microring involved in the present disclosure can be formed as one piece.

[0070] The embodiment of the present disclosure provides a wide tunable laser, comprising a first laser module, an external cavity module, and a second laser module connected in sequence; the end face of the first laser module away from the external cavity module has a first reflective film, and the end face of the second laser module away from the external cavity module has a second reflective film; the reflectivity of the first reflective film is greater than the reflectivity of the second reflective film; the first laser module or the second laser module is used to generate an optical signal and inject it into the external cavity module; the external cavity module is used to narrow the line width of the optical signal and select a mode for the optical signal, and transmit the optical signal that meets the preset mode to the second laser module or the first laser module; the optical signal that meets the preset mode goes back and forth between the first reflective film, the external cavity module, and the second reflective film for multiple times to form laser oscillation, and is output through the second reflective film. The embodiment of the present disclosure integrates the first laser module, the external cavity module, and the second laser module, and uses the first laser module or the second laser module to generate different optical signals and tune the optical signals in different scenarios, so that the tunable range of the laser provided by the embodiment of the present disclosure can fully cover the tuning range of the first laser module and the tuning range of the second laser module, thereby achieving the expansion of the laser tuning range; and the optical signal generated by the first laser module or the optical signal generated by the second laser module can be tuned in different scenarios, so the laser will not be affected by the expansion of the tuning range. The laser provided by the embodiment of the present disclosure can also form a single-mode laser oscillation between the first reflective film, the external cavity module, and the second reflective film through the optical signal, and is enhanced by the first laser module or the second laser module during the oscillation process, so that a high-power, narrow-linewidth single-mode laser can be output.

[0071] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present disclosure. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in the various embodiments of the present disclosure, the size of the serial number of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure. The serial numbers of the embodiments of the present disclosure are for description only and do not represent the advantages and disadvantages of the embodiments.

[0072] The above description is only a preferred embodiment of the present disclosure, and does not limit the patent scope of the present disclosure. All equivalent structural changes made by using the contents of the present disclosure and the drawings under the inventive concept of the present disclosure, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present disclosure.

Claims

1. A wide tunable laser, characterized in that: It includes a first laser module, an external cavity module and a second laser module connected in sequence; The end surface of the first laser module away from the external cavity module has a first reflective film, and the end surface of the second laser module away from the external cavity module has a second reflective film; the reflectivity of the first reflective film is greater than the reflectivity of the second reflective film; The first laser module or the second laser module is used to generate an optical signal and inject it into the external cavity module; The external cavity module is used to narrow the line width of the optical signal and select a mode for the optical signal, and transmit the optical signal satisfying a preset mode to the second laser module or the first laser module; The optical signal satisfying the preset mode travels back and forth between the first reflective film, the external cavity module and the second reflective film for multiple times to form laser oscillation, and is output through the second reflective film.

2. The wide tunable laser according to claim 1, characterized in that: The first laser module is used to generate an optical signal with a first tunable wavelength band, and the second laser module is used to generate an optical signal with a second tunable wavelength band, wherein the first tunable wavelength band is different from the second tunable wavelength band.

3. The wide tunable laser according to claim 2, characterized in that: The reflection band of the first reflection film at least covers the first tunable band and the second tunable band, and the reflection band of the second reflection film at least covers the first tunable band and the second tunable band.

4. The wide tunable laser according to claim 1, characterized in that: The external cavity module comprises at least three waveguides arranged along a first direction, and an extension direction of the waveguides intersects with the first direction; A micro-ring is arranged between any two adjacent waveguides among the at least three waveguides.

5. The wide tunable laser according to claim 4, characterized in that: The free spectrum range of each microring is different.

6. The wide tunable laser according to claim 4, characterized in that: The first waveguide and the last waveguide are provided with a first modulation unit, and the first modulation unit is a phase modulator.

7. The wide tunable laser according to claim 4, characterized in that: A second modulation unit is disposed on at least one of the micro-rings, and the second modulation unit is a thermal modulator or an electro-optical modulator.

8. The wide tunable laser according to claim 4, characterized in that: The microring is a racetrack-type microring, and a straight waveguide portion of the racetrack-type microring is coupled with two adjacent waveguides.

9. The wide tunable laser according to claim 1, characterized in that: The end surface of the first laser module connected to the external cavity module has a first anti-reflection film, and the end surface of the second laser module connected to the external cavity module has a second anti-reflection film.

10. The wide tunable laser according to claim 1, characterized in that: Also includes: a first coupling unit connected between the first laser module and the first end of the external cavity module, the first coupling unit being used to couple the optical signal output by the first laser module to the first end of the external cavity module, or to couple the optical signal output by the first end of the external cavity module to the first laser module; a second coupling unit connected between the second laser module and the second end of the external cavity module, the second coupling unit being used to couple the optical signal output by the second laser module to the second end of the external cavity module, or to couple the optical signal output by the second end of the external cavity module to the second laser module; the first end and the second end of the external cavity module are two opposite end faces of the external cavity module.

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