CN115832839A - Laser device - Google Patents

Abstract

The disclosed embodiment provides a laser, which includes: an optical device including at least a semiconductor optical amplifier and an optical output port; a first beam splitter including at least a first port, a second port, and a third port, the first port being connected to the optical device; the first microring resonator at least comprises two first bending waveguides and has a first free spectral range; a second microring resonator comprising at least two second curved waveguides, the second microring resonator having a second free spectral range, the second free spectral range being different from the first free spectral range; the first micro-ring resonator is coupled with the second port, the first micro-ring resonator is connected with the second micro-ring resonator through the connecting waveguide, and the second micro-ring resonator is coupled with the third port.

Description

Laser device

Technical Field

The present disclosure relates to the field of optical devices, and more particularly, to a laser.

Background

A laser is one of the most important optoelectronic devices, and has important applications in the fields of atomic physics, high-resolution spectroscopy, optical communication, laser radar, etc., which all require that the output light of the laser can be tuned to one or more specific wavelengths, so that a tunable semiconductor laser with excellent output characteristics has become an indispensable optical device. In the prior art, mode competition easily occurs in the tunable laser, so that the mode hopping phenomenon occurs and the stability of the laser is influenced. Therefore, how to improve the stability of the laser and ensure that the laser has higher optical output power and narrower laser linewidth is a problem to be solved urgently at present.

Disclosure of Invention

In view of this, the present disclosure provides a laser, including:

an optical device including at least a semiconductor optical amplifier and an optical output port;

a first beam splitter including at least a first port, a second port, and a third port, the first port being connected to the optical device;

a first microring resonator comprising at least two first curved waveguides, the first microring resonator having a first free spectral range;

a second microring resonator comprising at least two second curved waveguides, the second microring resonator having a second free spectral range, the second free spectral range being different from the first free spectral range;

the first micro-ring resonator is coupled with the second port, the first micro-ring resonator is connected with the second micro-ring resonator through a connecting waveguide, and the second micro-ring resonator is coupled with the third port.

In some embodiments, the first curved waveguide comprises at least: the inner wall is in a first arc shape, the outer wall is in a second arc shape, and the circle centers of the first inner wall and the first outer wall are different;

the second curved waveguide comprises at least: the second inner wall of third circular arc shape and the second outer wall of fourth circular arc shape, the second inner wall with the centre of a circle of second outer wall is different.

In some embodiments, a line connecting the centers of the first inner wall and the first outer wall is a symmetry axis of the first curved waveguide; and a connecting line of the circle centers of the second inner wall and the second outer wall is a symmetry axis of the second curved waveguide.

In some embodiments, the first microring resonator further comprises: at least two first straight waveguides connecting any two adjacent first curved waveguides;

the second microring resonator further comprises: at least two second straight waveguides connecting any two adjacent second curved waveguides.

In some embodiments, the first beam splitter is a 3dB beam splitter.

In some embodiments, the first splitter, the first microring resonator, and the second microring resonator are coupled two by two via an on-chip waveguide.

In some embodiments, the first microring resonator further comprises a first heating device;

the second microring resonator further comprises a second heating device.

In some embodiments, the optical device further comprises:

a first reflector coupled to the semiconductor optical amplifier, the first reflector including the optical output port, at least a portion of the input light of the first reflector exiting the optical output port;

the semiconductor optical amplifier is also connected to the first port.

In some embodiments, the optical device further comprises:

a second reflector connected to said semiconductor optical amplifier, said second reflector having input light totally reflected;

and the second beam splitter comprises a fourth port, a fifth port and a sixth port, the fourth port is connected with the semiconductor optical amplifier, the fifth port is the optical output port, and the sixth port is connected with the first port.

In some embodiments, where the fifth port and the sixth port are optical drop ports, the optical power of the fifth port is different from the optical power of the sixth port;

and under the condition that the fourth port and the fifth port are optical splitting ports, the optical power of the fourth port is different from that of the fifth port.

The laser provided by the embodiment of the disclosure comprises a first microring resonator and a second microring resonator, wherein the first microring resonator at least comprises two first bending waveguides; the second micro-ring resonator at least comprises two second bending waveguides, and the first free spectral path of the first micro-ring resonator is different from the second free spectral path of the second micro-ring resonator. Therefore, the laser provided by the embodiment of the disclosure locks the required laser wavelength by combining the vernier caliper effect through the first micro-ring resonator and the second micro-ring resonator with different free spectral ranges; by improving the structure of each micro-ring resonator, each micro-ring resonator is composed of at least two bent waveguides, so that each micro-ring resonator has a smaller radius, the free spectral range of each micro-ring resonator is increased, the mode competition and mode hopping phenomena of the laser are inhibited, the stability of the laser is improved, the laser has stable wavelength output, and meanwhile, a larger wavelength tuning range can be realized.

Drawings

Fig. 1 is a schematic diagram of a laser provided in an embodiment of the present disclosure;

fig. 2 is a schematic diagram of a first curved waveguide in a first microring resonator provided in an embodiment of the present disclosure;

fig. 3 is a schematic diagram of another first microring resonator provided in an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of another laser provided by embodiments of the present disclosure;

fig. 5 is a schematic diagram of a first curved waveguide in another first microring resonator provided in an embodiment of the present disclosure;

fig. 6 is a schematic diagram of yet another first microring resonator provided in an embodiment of the present disclosure;

fig. 7 is a schematic diagram of yet another laser provided by an embodiment of the present disclosure;

fig. 8 is a schematic diagram of another laser provided in the embodiments of the present disclosure.

Detailed Description

To facilitate an understanding of the present disclosure, exemplary embodiments of the present disclosure will be described in more detail below with reference to the associated drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present disclosure. It will be apparent, however, to one skilled in the art, that the present disclosure may be practiced without one or more of these specific details. In some embodiments, some technical features that are well known in the art are not described in order to avoid obscuring the present disclosure; that is, not all features of an actual embodiment may be described herein, and well-known functions and structures may not be described in detail.

In general, terms may be understood at least in part from the context of their use. For example, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in the singular or may be used to describe a combination of features, structures, or characteristics in the plural, depending, at least in part, on the context. Similarly, terms such as "a" or "the" may also be understood to convey a singular use or to convey a plural use, depending, at least in part, on the context. Additionally, the term "based on" may be understood as not necessarily intended to convey an exclusive set of factors, and may instead allow for the presence of additional factors that are not necessarily expressly described, again depending at least in part on the context.

Unless otherwise defined, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

In order to thoroughly understand the present disclosure, detailed steps and detailed structures will be set forth in the following description in order to explain the technical aspects of the present disclosure. The following detailed description of the preferred embodiments of the present disclosure, however, the present disclosure may have other embodiments in addition to these detailed descriptions.

Tunable lasers are of many types, such as monolithically integrated Distributed Feedback lasers (DFB), distributed Bragg Reflector lasers (DBR), vertical Cavity Surface Emitting Lasers (VCSEL), external Cavity lasers, etc., based on III-V material systems. Among these lasers, the external cavity laser has attracted attention because of its advantages such as a wide tunable range, a narrow line width of output laser, a good controllability of wavelength, and a good temperature stability.

The external cavity laser is one of the hottest light sources of the silicon optical chip. In the external cavity structure, a plurality of resonant cavities are usually adopted for mode selection, and a vernier caliper effect is utilized to lock a required lasing wavelength. One of the most commonly used resonant cavities is the micro-ring. In order to reduce link loss, the size of a common micro-ring is generally large, the interval of each wavelength is small, and mode competition is easy to occur, so that mode hopping occurs, and system stability is affected. The disclosed embodiments are generally directed to improvements in being tunable external cavity lasers.

Fig. 1 is a schematic structural diagram of a laser according to the present disclosure. As shown in fig. 1, an embodiment of the present disclosure provides a laser including:

an optical device 10 including at least a semiconductor optical amplifier 11 and an optical output port 12;

a first beam splitter 20 including at least a first port 201, a second port 202, and a third port 203, the first port 201 being connected to the optical device 10;

a first microring resonator 30 comprising at least two first curved waveguides 31 and 32, said first microring resonator having a first free spectral range;

a second microring resonator 40 comprising at least two second curved waveguides 41 and 42, said second microring resonator having a second free spectral range, said second free spectral range being different from said first free spectral range;

the first micro-ring resonator 30 is coupled to the second port 202, the first micro-ring resonator 30 is connected to the second micro-ring resonator 40 through a connecting waveguide, and the second micro-ring resonator 40 is coupled to the third port 203.

In the disclosed embodiment, as shown in fig. 1, the optical device 10 is a device including at least a semiconductor optical amplifier 11 and an optical output port 12, and can provide a light source of a laser and a light exit port of the laser. The Semiconductor Optical Amplifier 11 (SOA) is used as an on-chip light source and a gain medium for generating a spontaneous emission light and an amplified light signal, and a peak wavelength range of a gain spectrum covers a near ultraviolet to infrared band. In some embodiments, the semiconductor optical amplifier 11 is made of III-V semiconductor material or II-VI semiconductor material, and the active layer thereof has a structure of quantum well, quantum wire or quantum dot, and can be integrated on the silicon-based platform by flip chip bonding, forward mounting bonding, chip packaging, heterojunction bonding, heterojunction transfer or epitaxial growth.

In some embodiments, as shown in fig. 1, both ends of the semiconductor optical amplifier 11 are respectively plated with a partial reflective film and an antireflection film, wherein the antireflection film plated side is connected to the first beam splitter 20, and a light source is input into the first beam splitter 20; one side of the semiconductor optical amplifier 11 plated with a partial reflection film is connected with an optical output port 12 as a light exit port of the laser.

The optical device 10 is used in combination with other optical elements of the laser, and processes an optical signal a plurality of times to finally output laser light. That is, the semiconductor optical amplifier 11 in the optical device 10 generates the spontaneous emission light and amplifies the optical signal, while the other optical elements filter the optical signal and re-input the optical signal to the optical device 10 for amplification, and the generated laser light is output from the optical output port 12 of the optical device 10.

The first beam splitter 20, shown in fig. 1, is an optical device that splits an incident beam into two beams. In this embodiment, the first splitter 20 includes at least three ports: a first port 201, a second port 202 and a third port 203, wherein the first port 201 is an incident light port of the first beam splitter 20, is connected to the optical device 10, and receives an optical signal from the optical device 10; the second port 202 and the third port 203 are light emitting ports of the first splitter 20, the first splitter 20 splits the optical signal into two parts, and the two parts are emitted from the second port 202 and the third port 203, respectively, and the split light beams from the second port 202 and the third port 203 have the same power. On the other hand, the first beam splitter 20 may also be used as a coupler, that is, two beams from the second port 202 and the third port 203 are combined into one beam and output through the first port 201.

It should be noted that, in the embodiments of the present disclosure, the passive waveguide material may be used for both the beam splitter and the microring resonator, and the specific material may be any one or a combination of the following materials: silicon, silicon nitride, silicon dioxide, polymeric materials, and the like.

In the embodiment of the present disclosure, the first microring resonator 30 and the second microring resonator 40 are composed of at least two curved waveguides, have a very small radius, which may be smaller than 1.5 microns, and are used to filter the optical signal input thereto, so as to obtain laser outputs with different wavelengths. To achieve a larger wavelength tuning range, the first microring resonator 30 and the second microring resonator 40 in the present disclosure are provided with larger and different free spectral ranges. In some embodiments, the difference between the free spectral paths of the first microring resonator 30 and the second microring resonator 40 is much smaller than the free spectral path of the first microring resonator 30 (or the second microring resonator 40) to improve the stability of the laser.

The first microring resonator 30 and the second microring resonator 40 are connected by a connecting waveguide, which may be an on-chip waveguide 53, and may be in the form of a straight waveguide or a curved waveguide. In practical applications, the position and shape of the connecting waveguide may be set according to the positions of the first microring resonator 30 and the second microring resonator 40.

In some embodiments, as shown in fig. 1, the first microring resonator 30 and the second microring resonator 40 are single microring resonators composed of two curved waveguides whose inner and outer walls are both circular arc structures, the first microring resonator 30 is composed of a first curved waveguide 31 and a first curved waveguide 32, and the second microring resonator 40 is composed of a second curved waveguide 41 and a second curved waveguide 42 2. Here, the first bend waveguide and the second bend waveguide are made of the same material, and since the bend radius of the first bend waveguide is smaller than that of the second bend waveguide, the free spectral range of the first micro-ring resonator is made larger than that of the second micro-ring resonator, and the effective radius of the first micro-ring resonator is made smaller than that of the second micro-ring resonator, so that the free spectral ranges of the first micro-ring resonator 30 and the second micro-ring resonator 40 are different. The effective radius is determined by the radius of the inner wall and the radius of the outer wall of the micro-ring resonator, as shown in fig. 2, the effective radius R is approximately equal to the distance from the position of the origin O of the micro-ring resonator in the y-axis direction to the inner wall, plus the difference between the distance of the inner wall and the distance of the outer wall, which is equal to R ≈ OS1+1/2 (OS 3-OS 1). It should be noted that, in the embodiment of the present disclosure, the effective radius of the first microring resonator 30 and the effective radius of the second microring resonator 40 are not limited, and only the first microring resonator 30 and the second microring resonator 40 are required to have larger and different free spectral ranges.

In some embodiments, the first micro-ring resonator and the second micro-ring resonator may also be a structure in which 4 circular arc structures are connected two by two, or a structure in which 4 circular arc structures are connected two by two through a straight line structure, that is, a structure similar to a run-to shape, that is, a structure including a circular arc portion (curved waveguide) and a straight line portion (straight waveguide), such as the first micro-ring resonator shown in fig. 3, which is composed of four first curved waveguides 33. A laser corresponding to the micro-ring resonator structure shown in fig. 3 is shown in fig. 4, and takes a first micro-ring resonator 30 as an example, and the specific shape thereof is shown in fig. 3, and is composed of 4 first curved waveguides 33 in different directions as shown in fig. 5. Other components in fig. 4 are substantially the same as those in fig. 1, and are not described again here. In other embodiments, the microring resonator may be formed by connecting one curved waveguide (the direction may be different from that of fig. 3) as shown in fig. 3 and two curved waveguides (the direction may be different from that of fig. 5) as shown in fig. 5. The structure of the micro-ring resonator is not limited in the embodiments of the present disclosure, and only the micro-ring resonator is required to have a filter function.

In an embodiment of the present disclosure, as shown in fig. 1, a laser includes: a semiconductor optical amplifier 11, a first beam splitter 20, a first microring resonator 30, a second microring resonator 40 and an optical output port 12, the relationship of these components being as shown. Specifically, one side of the semiconductor optical amplifier 11 is connected to the optical output port 12, and the other side is connected to an incident optical port, i.e., a first port 201, of the first beam splitter 20; one output end second port 202 of the first beam splitter 20 is coupled to one side of the first micro-ring resonator 30, the other output end third port 203 is coupled to one side of the second micro-ring resonator 40, and the other side of the first micro-ring resonator 30 is coupled to the other side of the second micro-ring resonator 40, so that a loop is formed among the first beam splitter 20, the first micro-ring resonator 30, and the second micro-ring resonator 40. It should be noted that the coupling and connection between the components in the embodiments of the present disclosure may be a coupling manner commonly used by those skilled in the art, such as a butt coupling or a grating coupling, or may be a direct connection through a waveguide.

The semiconductor optical amplifier 11 generates spontaneous emission light and amplified light, and transmits the light to the first port 201 of the first beam splitter 20, the first beam splitter 20 divides the light into two, wherein one beam of light is transmitted to one side of the first micro-ring resonator 30 through the second port 202, and the first micro-ring resonator 30 processes the light beam and outputs the processed light beam to the second micro-ring resonator 40 through the other side; the other beam of light is transmitted to one side of the second micro-ring resonator 40 through the third port 203, and the second micro-ring resonator 40 processes the beam of light and outputs the processed beam of light to the first micro-ring resonator 30 through the other side; thus, the first microring resonator 30 and the second microring resonator 40 lock the required lasing wavelength by combining with the vernier caliper effect, and re-input the filtered light to the first beam splitter 20, the first beam splitter 20 combines the two paths of light and inputs the combined light to the semiconductor optical amplifier 11, the semiconductor optical amplifier 11 amplifies the light, and the generated laser is finally output from the optical output port 12.

According to the laser provided by the embodiment of the disclosure, the required lasing wavelength is locked by combining the vernier caliper effect through the first micro-ring resonator 30 and the second micro-ring resonator 40 with different free spectral ranges; by improving the structure of each micro-ring resonator, each micro-ring resonator is composed of at least two bending waveguides, so that each micro-ring resonator has a very small radius, the free spectral range of each micro-ring resonator is increased, the mode competition and mode hopping phenomena of the laser are inhibited, the stability of the laser is improved, the laser has stable wavelength output, and meanwhile, a large wavelength tuning range can be realized.

In some embodiments, as shown in FIG. 2, the first curved waveguide 32 includes at least: the first inner wall 311 of first circular arc shape and the first outer wall 312 of second circular arc shape, first inner wall 311 with the centre of a circle of first outer wall 312 is different. For convenience of illustration, fig. 2 shows only one direction of the first curved waveguide, i.e., the first curved waveguide 32, and the first curved waveguide 31 shown in fig. 1 has the same structure and the opposite direction as the first curved waveguide 32 in fig. 2, and they are opposite and connected to constitute the first microring resonator 30.

The second curved waveguide, i.e. the second curved waveguide 41 and the second curved waveguide 42 in fig. 1 (not shown in fig. 2, the structure may be similar to the first curved waveguide, and the size of the inner wall of the second curved waveguide may be different from that of the inner wall of the first curved waveguide; and the size of the outer wall in the second curved waveguide may also be different from that of the outer wall of the first curved waveguide) at least comprises: the second inner wall of third circular arc shape and the second outer wall of fourth circular arc shape, the second inner wall with the centre of a circle of second outer wall is different.

For convenience of describing the structure of the first curved waveguide, a plane rectangular coordinate system is used herein to divide the plane into four quadrants.

Fig. 2 is a schematic structural diagram of a first curved waveguide 32 provided by the present disclosure. The first curved waveguide 32 is located in a first quadrant and a fourth quadrant, and includes a first inner wall 311 and a first outer wall 312, where the first inner wall 311 is in a first arc shape, a start point S1 and an end point S2 of the first inner wall 311 are located on a y-axis, and a circle center of the first inner wall 311 is A1 (A1, 0); the first outer wall 312 is in a second arc shape, the starting point S3 of the first outer wall 312 is located in the first quadrant, the end point S4 is located in the fourth quadrant, the circle center of the first outer wall 312 is A2 (A2, 0), A1 is not equal to A2, that is, the circle center A1 of the first inner wall 311 does not coincide with the circle center A2 of the first outer wall 312.

In some embodiments, the start and end points of the first outer wall 312 are in the second quadrant and the third phenomenon, respectively, or are co-located on the y-axis. That is, if the abscissa of the start point S3 and the end point S4 of the first outer wall is L1 and L2, L1 and L2 in the illustration may be negative values, 0, or positive values; l1 and L2 may be the same or different in size.

Fig. 5 is a schematic structural diagram of another first curved waveguide 33 provided by the present disclosure. The first curved waveguide 33 is located in a first quadrant and includes a first inner wall 311 and a first outer wall 312, where the first inner wall 311 is in a first arc shape, a starting point S3 of the first inner wall 311 is located on the y axis, an ending point S4 of the first inner wall 311 is located on the x axis, and a circle center of the first inner wall 311 is A3 (A3, A3); the first outer wall 312 is in a second arc shape, the starting point S5 and the end point S6 of the first outer wall 312 are both located in the first quadrant, the circle center of the first outer wall 312 is A4 (A4, A4), and A3 is not equal to A4, that is, the circle center A3 of the first inner wall 311 does not coincide with the circle center A4 of the first outer wall 312. In some embodiments, the start and end points of the first outer wall 312 are located in the x-axis and the y-axis, respectively, or in the second quadrant and the fourth quadrant, respectively. That is, if the abscissa of the start point and the end point of the first outer wall 312 is L1 and L2, L1 and L2 in the illustration may be negative values, 0, or positive values; the sizes of L1 and L2 are generally the same.

As shown in fig. 2 and 5, in the embodiment of the present disclosure, the radius of the first inner wall 311 is R1, the radius of the first outer wall 312 is R2, and R2 is greater than R1. The effective radius of the first curved waveguide 33 in FIG. 5 is similar to that of the first curved waveguide 32 in FIG. 2, and as shown in FIG. 5, the effective radius R is approximately the distance from the origin O to S5 plus half the distance between S5 and S7, i.e., R ≈ OS5+1/2 (OS 7-OS 5), and the effective radius of the first curved waveguide is inversely related to its free spectral range. The embodiment of the present disclosure optimizes the curved shape of the first curved waveguide by making the circle centers of the arcs where the inner wall and the outer wall of the first curved waveguide are not coincident, reduces the effective radius of the first curved waveguide, and at the same time, makes the effective radius of the first curved waveguide possess a larger effective refractive index under the condition of being extremely small, that is, the first micro-ring resonator 30 composed of the first curved waveguide can simultaneously realize an extremely small radius and an extremely low loss, so that the first micro-ring resonator 30 has a larger free spectral range and a larger quality factor, thereby inhibiting the mode competition and the mode hopping phenomenon of the laser, simultaneously ensuring that the laser can have higher optical power output and a smaller laser line width, and improving the stability of the laser.

In the embodiment of the present disclosure, the second curved waveguide and the first curved waveguide have similar structures, and their effective radii are different, which are not described herein again.

In some embodiments, a line connecting the centers of the first inner wall 311 and the first outer wall 312 is a symmetry axis of the first curved waveguide 33; and a connecting line of the circle centers of the second inner wall and the second outer wall is a symmetry axis of the second curved waveguide.

As shown in fig. 2, the first inner wall 311 has a center A1 (A1, 0), the first outer wall 312 has a center A2 (A2, 0), both A1 and A2 are located on the x-axis, and A2 may be larger than A1. The line connecting the circle centers of the first inner wall and the first outer wall 312 is a straight line where the x-axis is located, the distance from any point on the first inner wall 311 to the point A1 is equal, the distance from any point on the first outer wall 312 to the point A2 is equal, and the straight line where the x-axis is located is taken as the symmetry axis of the first inner wall 311 and the first outer wall 312, so that the straight line where the x-axis is located is taken as the symmetry axis of the first inner wall 311 and the first outer wall 312 of the first curved waveguide 33, that is, the straight line where the line connecting the circle centers of the first inner wall 311 and the first outer wall 312 is located is taken as the symmetry axis of the first curved waveguide 33.

As shown in fig. 5, the circle center of the first inner wall 311 is A3 (A3, A3), the circle center of the first outer wall 312 is A4 (A4, A4), the straight line where A3 and A4 are located is a straight line z, where an included angle between the straight line z and the x axis is 45 °, a distance from any point on the first inner wall 311 to a point A3 is equal, a distance from any point on the first outer wall 312 to a point A4 is equal, and the straight line z is used as a symmetry axis for the first inner wall 311 and the first outer wall 312, so that the first inner wall 311 and the first outer wall 312 of the first curved waveguide 33 use the straight line z as a symmetry axis, that is, the straight line where a connection line of the circle centers of the first inner wall 311 and the first outer wall 312 is located is used as a symmetry axis for the first curved waveguide 33.

In the embodiment of the present disclosure, the first curved waveguide 33 uses a connection line between the circle centers of the first inner wall 311 and the first outer wall 312 as a symmetry axis, so as to optimize the structure of the first curved waveguide 33, and thus, the radius of the first micro-ring resonator 30 formed by the first curved waveguide 33 is smaller and the loss is lower, thereby ensuring that the laser can have higher optical power output and smaller laser line width, and improving the stability of the laser.

In the embodiment of the present disclosure, since the second curved waveguide and the first curved waveguide have similar structures, the structural relationship between the second inner wall and the second outer wall is not described herein again.

In some embodiments, the first microring resonator 30 further includes: at least two first straight waveguides connecting any two adjacent first curved waveguides;

the second microring resonator 40 further includes: at least two second straight waveguides connecting any two adjacent second curved waveguides.

It should be noted that the number of the first straight waveguides is the same as the number of the first curved waveguides, so that at least two first curved waveguides are alternately connected end to end with at least two first straight waveguides to form a ring waveguide.

Similarly, the number of the second straight waveguides is the same as the number of the second curved waveguides.

Fig. 6 is a schematic structural diagram of a first microring resonator 30 according to an embodiment of the present disclosure, where the first microring resonator 30 includes: the two first curved waveguides include a first curved waveguide 37 and a first curved waveguide 38, and further include two first straight waveguides connecting the two first curved waveguides, that is, a first straight waveguide 39a and a first straight waveguide 39b shown in fig. 6, the first straight waveguide 39a and the first straight waveguide 39b are respectively located between the two first curved waveguides, and the first curved waveguide 37 and the first curved waveguide 38 are connected via the first straight waveguide 39a and the first straight waveguide 39b to adjust a free spectral range of the first microring resonator.

It should be noted that the first curved waveguide 37 shown in fig. 6 and the first curved waveguide 32 shown in fig. 2 may be curved waveguides having the same shape, and the first curved waveguide 38 and the first curved waveguide 32 shown in fig. 2 may be curved waveguides having the same shape but different directions.

In the embodiment of the disclosure, the first micro-ring resonator composed of the first curved waveguide and the first straight waveguide has a very small inner diameter and a very low loss, and increases its free spectral range and quality factor, thereby suppressing mode competition and mode hopping of the laser, ensuring that the laser can have a higher optical power output and a smaller laser linewidth, and improving the stability of the laser.

In the embodiment of the present disclosure, since the second curved waveguide and the first curved waveguide have similar structures, the structural relationship between the second micro-ring resonator and the second straight waveguide is not described herein again.

In some embodiments, as shown in FIG. 1, the first beam splitter 20 is a 3dB beam splitter.

The 3dB splitter shown in fig. 1 can equally distribute the energy of the incident light into two outgoing beams, that is, the splitting ratio is: 50%:50 percent. In the disclosed embodiment, the beam energy split by the second port 202 and the third port 203 of the first beam splitter 20 is equal; meanwhile, the first beam splitter 20 can couple the beams of the second port 202 and the third port 203, and the coupling coefficient is 50%:50 percent.

In some embodiments, as shown in fig. 1, the first beam splitter 20, the first microring resonator 30 and the second microring resonator 40 are coupled two by an on-chip waveguide.

As shown in fig. 1, the second port 202 of the first beam splitter 20 is coupled to one side of the first micro-ring resonator 30 through the on-chip waveguide 51, the third port 203 of the first beam splitter 20 is coupled to one side of the second micro-ring resonator 40 through the on-chip waveguide 52, and the other side of the first micro-ring resonator 30 and the other side of the second micro-ring resonator 40 are coupled through the on-chip waveguide 53.

In the embodiment of the present disclosure, the first beam splitter 20, the first micro-ring resonator 30, and the second micro-ring resonator 40 are coupled with each other two by two through the on-chip waveguide, and the free spectral range is two and large, and mode hopping is not easy, so that the system stability is improved.

In some embodiments, as shown in figure 1,

the first microring resonator 30 further comprises a first heating device 54;

the second microring resonator 40 further comprises a second heating device 55.

The first heating device 54 and the second heating device 55 may be heating resistor sheets, and the material thereof may be an on-sheet resistance material of titanium nitride, tungsten, or the like. Illustratively, the heater may be placed on the uncoupled region of the annular ring, e.g., the first heating device 54 in fig. 1 is placed near a portion of the exterior of the first microring resonator 30 and the second heating device 55 is placed near a portion of the exterior of the second microring resonator 40. According to the embodiment of the disclosure, the first micro ring resonator 30 and the second micro ring resonator 40 are heated by the first heating device and the second heating device to adjust the positions of the resonance peaks of the first micro ring resonator 30 and the second micro ring resonator 40, so that a required resonance wavelength is selected, the laser device stably outputs laser light with a specific wavelength, and the stability of the laser device is improved.

In some embodiments, the first heating device 54 may be fixed to a side of the first micro-ring resonator 30, and the second heating device 55 may be fixed to a side of the second micro-ring resonator 40.

In some embodiments, as shown in fig. 7, the optical device 10 further comprises:

a first reflector 13 connected to the semiconductor optical amplifier 11, the first reflector 13 including the optical output port 12, at least a portion of the input light of the first reflector 13 being emitted from the optical output port;

the semiconductor optical amplifier 11 is also connected to the first port 201.

The first reflector 13 is a reflective device having a fixed reflectance to realize optical feedback. The first reflector 13 in fig. 6 is an on-chip integrated partial reflector, one side of the first reflector 13 is connected to the semiconductor optical amplifier 11, and receives an optical signal from the semiconductor optical amplifier 11, a part of the light is reflected by the first reflector 13 and enters the semiconductor optical amplifier 11, and the other part of the light is emitted from the other side of the first reflector 13. Here, one end of the first reflector 13 emitting light is the light output port 12 of the optical device 10, i.e., the light exit port of the laser.

In the embodiment of the present disclosure, one end of the semiconductor optical amplifier 11 is connected to the first reflector 13, and the other end is connected to the first port 201 of the first beam splitter 20, the reflected light of the first reflector 13 enters the first port 201 of the first beam splitter 20 after being amplified by the semiconductor optical amplifier 11, and then passes through the filtering of the first micro-ring resonator 30 and the second micro-ring resonator 40, the light returns to the semiconductor optical amplifier 11 again to be amplified, and so on, and finally the laser light is emitted from the optical output port 12 of the first reflector 13.

The disclosed embodiments achieve laser output by using a first reflector with an optical output port to achieve optical feedback, forming the resonant cavity of the laser.

In some embodiments, as shown in fig. 8, the optical device 10 further comprises:

a second reflector 14 connected to the semiconductor optical amplifier 11, wherein the input light of the second reflector 14 is totally reflected;

and a second beam splitter 15, where the second beam splitter includes a fourth port 151, a fifth port 152 and a sixth port 153, the fourth port is connected to the semiconductor optical amplifier 11, the fifth port 152 is the optical output port 12, and the sixth port 153 is connected to the first port 201.

The second reflector 14 is an optical device that can totally reflect light. One side of the second reflector 14 is connected to the semiconductor optical amplifier 11, receives light from the semiconductor optical amplifier 11, and all the light is reflected by the second reflector 14 and enters the semiconductor optical amplifier 11.

The second beam splitter 15 is an optical device that splits an incident beam into two beams. In this embodiment, the fourth port 151 is an incident light port of the second beam splitter, is connected to the semiconductor optical amplifier 11, and receives light from the semiconductor optical amplifier 11; the light is split into two light beams by the second beam splitter 15 and output from the fifth port 152 and the sixth port 153, respectively. In the present disclosure, the fifth port 152 of the second beam splitter 15 is set as the optical output port 12 of the laser, the sixth port 153 is connected to the first port 201 of the first beam splitter 20, light enters the first beam splitter 20 through the sixth port, and then is filtered by the first micro-ring resonator 30 and the second micro-ring resonator 40, the light returns to the semiconductor optical amplifier 11 in the original path again and is amplified, and so on, and finally the laser is emitted from the fifth port 152 of the second beam splitter 20.

The disclosed embodiment implements optical feedback by using a second reflector 14, while setting one end of the second beam splitter as the optical output port 12, forming a resonant cavity of the laser, thereby implementing laser output.

In some embodiments, in the case where the fifth port 152 and the sixth port 153 are optical splitting ports, the optical power of the fifth port 152 is different from that of the sixth port 153;

in the case where the fourth port 151 and the fifth port 152 are optical splitting ports, the optical power of the fourth port 151 is different from that of the fifth port 152, that is, the second beam splitter 15 is an asymmetric beam splitter.

The asymmetric beam splitter is an optical device for splitting one incident beam into two beams, and the two split beams have different powers. The asymmetric beam splitter comprises an input and two outputs and wherein the output port with the smaller split can be used as the laser output. The fifth port and the sixth port of the second beam splitter 15 may be optical splitting ports, and the fourth port is an input port, for example, if the optical splitting of the fifth port is small, the fifth port is used as a laser port, and the sixth port may be a common output port, and is used for coupling connection with other ports; in another embodiment, the fourth port and the fifth port may be optical splitting ports, and the sixth port is an input port. As shown in fig. 7, the input end of the asymmetric beam splitter is a fourth port 151, and the output end is a fifth port 152 and a sixth port 153, where optical powers of the fifth port 152 and the sixth port 153 are different, and an optical power of the fifth port 152 may be greater than an optical power of the sixth port 153 or smaller than an optical power of the sixth port 153, and for example, if the optical power of the fifth port 152 is smaller, the asymmetric beam splitter may be used as a laser output port.

The above-described embodiments are merely illustrative of the principles of the present disclosure and their efficacy, and are not intended to limit the disclosure. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present disclosure. Accordingly, it is intended that all equivalent modifications or changes be made by those skilled in the art without departing from the spirit and technical spirit of the present disclosure and be covered by the claims of the present disclosure.

Claims (10)

1. A laser, comprising:

an optical device including at least a semiconductor optical amplifier and an optical output port;

a first beam splitter including at least a first port, a second port, and a third port, the first port being connected to the optical device;

a first microring resonator comprising at least two first curved waveguides, the first microring resonator having a first free spectral range;

a second microring resonator comprising at least two second curved waveguides, the second microring resonator having a second free spectral range, the second free spectral range being different from the first free spectral range;

the first micro-ring resonator is coupled with the second port, the first micro-ring resonator is connected with the second micro-ring resonator through a connecting waveguide, and the second micro-ring resonator is coupled with the third port.

2. The laser of claim 1,

the first curved waveguide comprises at least: the inner wall is in a first arc shape, the outer wall is in a second arc shape, and the circle centers of the first inner wall and the first outer wall are different;

the second curved waveguide comprises at least: the second inner wall of third circular arc shape and the second outer wall of fourth circular arc shape, the second inner wall with the centre of a circle of second outer wall is different.

3. The laser of claim 2,

a connecting line of the circle centers of the first inner wall and the first outer wall is a symmetry axis of the first curved waveguide; and a connecting line of the circle centers of the second inner wall and the second outer wall is a symmetry axis of the second curved waveguide.

4. The laser of claim 3,

the first microring resonator further comprises: at least two first straight waveguides connecting any two adjacent first curved waveguides;

the second microring resonator further comprises: at least two second straight waveguides connecting any two adjacent second curved waveguides.

5. The laser of claim 1, wherein the first beam splitter is a 3dB beam splitter.

6. The laser of claim 1, wherein the first beam splitter, the first microring resonator, and the second microring resonator are coupled two by two via an on-chip waveguide.

7. The laser of claim 1,

the first microring resonator further comprises a first heating device;

the second microring resonator further comprises a second heating device.

8. The laser of claim 1, wherein the optical arrangement further comprises:

a first reflector coupled to the semiconductor optical amplifier, the first reflector including the optical output port, at least a portion of the input light of the first reflector exiting the optical output port;

the semiconductor optical amplifier is also connected with the first port.

9. The laser of claim 1, wherein the optical arrangement further comprises:

a second reflector connected to the semiconductor optical amplifier, wherein the input light of the second reflector is totally reflected;

and the second beam splitter comprises a fourth port, a fifth port and a sixth port, the fourth port is connected with the semiconductor optical amplifier, the fifth port is the optical output port, and the sixth port is connected with the first port.

10. The laser of claim 9, wherein, in a case where the fifth port and the sixth port are optical splitting ports, optical power of the fifth port and the sixth port are different;

and under the condition that the fourth port and the fifth port are optical splitting ports, the optical power of the fourth port is different from that of the fifth port.

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