CN215377956U

CN215377956U - External cavity laser

Info

Publication number: CN215377956U
Application number: CN202121380680.6U
Authority: CN
Inventors: 涂文凯
Original assignee: Tongling Xuchuang Technology Co ltd; Innolight Technology Suzhou Ltd
Current assignee: Tongling Xuchuang Technology Co ltd; Innolight Technology Suzhou Ltd
Priority date: 2021-06-21
Filing date: 2021-06-21
Publication date: 2021-12-31
Anticipated expiration: 2031-06-21
Also published as: WO2022267356A1

Abstract

The utility model discloses an external cavity laser, which comprises a resonant cavity, wherein the resonant cavity comprises a first cavity surface and a second cavity surface; a gain chip is arranged in the resonant cavity; a focusing lens is further arranged between the gain chip and the second cavity surface; the light beam emitted by the gain chip is converged on the second cavity surface through the focusing lens and resonated between the first cavity surface and the second cavity surface; wherein a gap is formed between the focusing lens and the second cavity surface. The utility model has the technical effects of increasing the coupling tolerance of the lens in the resonant cavity, saving the space occupied by the resonant cavity and improving the light-emitting power of the resonant cavity.

Description

External cavity laser

Technical Field

The utility model relates to the field of optical communication, in particular to an external cavity laser.

Background

Long-distance transmission is always an important difficulty in the field of optical communication, and the problem can be well solved by utilizing coherent optical communication. Wavelength tunable lasers are core devices of coherent optical transmitters. The development trend of tunable lasers is that the packages are smaller and smaller, the light emitting power is larger and larger, and the power consumption is lower and lower.

In order to improve the tolerance of coupling in the cavity of the laser resonator and reduce the coupling difficulty, a self-focusing lens is usually added in the resonator, and one cavity surface of the resonator is arranged at the planar end of the self-focusing lens. The self-focusing lens focuses the light beam emitted by the gain chip onto the cavity surface. Although the scheme improves the coupling tolerance in the cavity and reduces the coupling difficulty, the scheme generally has three disadvantages: the first is that the focal length of the self-focusing lens is long, which results in that the size of the resonant cavity cannot be further reduced, and is not beneficial to the miniaturization package of the laser. Secondly, due to size limitation, the phenomenon that the beam waist of the light beam output by the self-focusing lens and the laser collimating lens is not matched exists, and in order to ensure the light output power of the resonant cavity, the curvature of the self-focusing lens needs to be changed, so that the length of the self-focusing lens is greatly changed and is limited by the whole length size, and the self-focusing lens is generally difficult to match. Thirdly, the self-focusing lens is manufactured generally with a tolerance in the length direction, which has a great influence on the light beam, so that the light spot behind the collimating lens is not matched with the light spot of the self-focusing lens easily, and the tolerance in the length dimension directly causes the reduction of the light output power of the resonant cavity.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problems that the size of a resonant cavity of the existing laser is long, the focal point of a self-focusing lens is not matched with the beam waist of a collimating lens, the length tolerance of the self-focusing lens is large, and the light output power of the resonant cavity is influenced.

In order to achieve the above object, the present invention provides an external cavity laser, comprising a resonant cavity, wherein the resonant cavity comprises a first cavity surface and a second cavity surface; a gain chip is arranged in the resonant cavity; a focusing lens is further arranged between the gain chip and the second cavity surface; the light beam emitted by the gain chip is converged on the second cavity surface through the focusing lens and resonated between the first cavity surface and the second cavity surface; wherein a gap is formed between the focusing lens and the second cavity surface.

Further, the external cavity laser further comprises a housing; the shell is internally provided with an accommodating cavity, and the resonant cavity, the gain chip and the focusing lens are arranged in the accommodating cavity.

Further, the external cavity laser further comprises an isolator, the second cavity surface is a laser exit cavity surface, and the isolator is located in a laser light path output by the second cavity surface.

Further, the second cavity surface is arranged on one surface of the isolator, which is close to the resonant cavity; or, the external cavity laser further includes a partial reflector, and the second cavity surface is located on the partial reflector.

Further, the first cavity surface is disposed at an end surface of the gain chip away from the gain chip.

Furthermore, the laser also comprises a collimating lens and a tunable filter, the collimating lens and the tunable filter are located between the gain chip and the focusing lens, a light beam emitted by the gain chip is collimated by the collimating lens and then enters the tunable filter, and the wavelength of the laser output by the external cavity laser is tuned by the tunable filter.

Further, the laser also comprises an optical monitoring component for monitoring the light extraction efficiency of the external cavity laser.

Furthermore, the optical monitoring assembly comprises an optical monitoring detector and a light splitting piece located between the focusing lens and the second cavity surface, the light splitting piece divides the light in the resonant cavity into a main light beam and a split light beam, the main light beam resonates in the resonant cavity, and the split light beam enters the optical monitoring detector.

Further, the external cavity laser also comprises a coupling lens and an optical fiber, and the shell is provided with an optical interface and an electrical interface; one end of the optical fiber is arranged in the optical interface; the coupling lens couples the laser light output from the resonant cavity into the optical fiber and transmits the laser light out of the external cavity laser through the optical fiber.

Furthermore, the laser also comprises a semiconductor refrigerator and a thermistor, and the gain chip and the thermistor are arranged on the semiconductor refrigerator.

The utility model has the technical effects that the independent focusing lenses are arranged in the cavity surface in the resonant cavity, and the light focus is positioned on the second cavity surface through the coupling focusing lens, thereby increasing the coupling tolerance, not influencing the light-emitting efficiency of the resonant cavity, effectively shortening the cavity length, being beneficial to miniaturization packaging, or using the saved space for the adjustable filter, increasing the interval between devices in the adjustable filter, thereby reducing the phenomenon of thermal crosstalk and further improving the light modulation performance of the adjustable filter.

Drawings

FIG. 1 is a side view of an external cavity laser provided in embodiment 1 of the present invention;

fig. 2 is a top view of an external cavity laser provided in embodiment 1 of the present invention;

FIG. 3 is a side view of an external cavity laser provided in embodiment 2 of the present invention;

fig. 4 is a top view of an external cavity laser provided in embodiment 2 of the present invention.

Description of reference numerals:

100. an external cavity laser; 200. an external cavity laser; 101. a housing; 102. an accommodating chamber; 201. a housing; 202. an accommodating chamber;

1. a gain chip; 2. a collimating lens; 3. an adjustable filter; 4. a focusing lens; 5. a light monitoring assembly; 6. an isolator; 7. a coupling lens; 8. an optical fiber; 9. a semiconductor refrigerator; 10. a thermistor;

11. a first cavity surface;

51. a light monitoring detector; 52. a light splitting sheet;

61. a second cavity surface;

110. a conductive substrate; 111. a base.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Furthermore, it should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, and are not intended to limit the present invention. In the present invention, unless otherwise specified, the use of directional terms such as "upper" and "lower" generally means upper and lower in the actual use or operation of the device, particularly in the orientation of the figures of the drawings; while "inner" and "outer" are with respect to the outline of the device.

The embodiment of the utility model provides an external cavity laser, which comprises a resonant cavity, wherein the resonant cavity comprises a first cavity surface and a second cavity surface, a gain chip and a focusing lens are arranged in the resonant cavity, and the focusing lens is positioned between the gain chip and the second cavity surface. The light beam emitted by the gain chip is converged on the second cavity surface through the focusing lens and resonated between the first cavity surface and the second cavity surface; the focusing lens and the second cavity surface are respectively arranged separately, and a gap is arranged between the focusing lens and the second cavity surface. The first cavity surface 11 is disposed on a side of the gain chip 1 away from the second cavity surface 61, and a resonant cavity is formed between the first cavity surface 11 and the second cavity surface 61. In the following embodiments, the first cavity surface 11 is taken as a total reflection surface, and the second cavity surface 61 is taken as a partial reflection surface (laser output cavity surface).

This will be described in detail below. It should be noted that the following description of the embodiments is not intended to limit the preferred order of the embodiments.

Example 1

As shown in fig. 1 and fig. 2, the present embodiment provides an external cavity laser 100, which includes a housing 101, an accommodating cavity 102 is disposed in the housing 101, and the accommodating cavity 102 accommodates therein: a gain chip 1, a second cavity surface 61, a first cavity surface 11, and a focusing lens 4. Illustratively, the external cavity laser 100 further includes one or more of the following: collimating lens 2, tunable filter 3, optical monitoring assembly 5, isolator 6, coupling lens 7, optical fiber 8, semiconductor refrigerator 9, and thermistor 10.

In the present embodiment, the gain chip 1 is a semiconductor element used as an optical gain medium of the laser 100, wherein the gain chip 1 is a Tunable Light Source (TLS) that emits light under excitation of a pump source.

The collimating lens 2 is disposed on the light emitting side of the gain chip 1, and in this embodiment, the collimating lens 2 is disposed on the left side of the gain chip 1. The collimating lens 2 is used for collimating the light emitted from the gain chip 1 to form parallel light, which may also be called collimated light.

The tunable filter 3(Etalon assembly) is disposed on a side of the collimating lens 2 away from the gain chip 1, and in this embodiment, the tunable filter 3 is disposed on a left side of the collimating lens 2. Illustratively, the tunable filter 3 includes an optical etalon, and is capable of adjusting and controlling the wavelength of the collimated light, allowing the collimated light with a wavelength in a specific range to transmit, and filtering out the collimated light in other wavelength ranges, so that the transmitted light resonates in the resonant cavity, that is, the tunable filter 3 selects the wavelength of the light generating resonance, and the output laser is a narrow-linewidth laser.

The focusing lens 4 is disposed on a side of the tunable filter 3 away from the collimating lens 2, and in this embodiment, the focusing lens 4 is disposed on a left side of the tunable filter 3.

In the process of assembling the external cavity laser 100, the position of the focusing lens 4 may be adjusted to achieve the optimal coupling state, that is, the position of the focusing lens 4 is adjusted to make the focal point of the light fall on the second cavity surface 61 of the resonant cavity 101, so that the light-emitting efficiency of the external cavity laser 100 is optimal, and then the focusing lens 4 is fixed at the optimal coupling position.

In this embodiment, the optical monitoring assembly 5 includes a light monitoring detector 51 (MPD) and a light splitter 52, where the light splitter 52 is disposed between the focusing lens 4 and the tunable filter 3 to split the light beam in the resonant cavity into a main light beam with relatively large power and a sub-light beam with relatively small power, the main light beam resonates in the resonant cavity, and the sub-light beam is incident into the light monitoring detector 51. The optical monitoring detector 51 is used for monitoring the output power of the external cavity laser 100. The proportion of the beam splitter 52 is 1-10%, and in the embodiment, it is preferably 2-5%.

Of course, in other embodiments of the present application, the optical monitoring component 5 may also be disposed outside the gain chip 1, that is, outside the resonant cavity, and can achieve the monitoring effect on the laser.

The isolator 6 is arranged outside the second cavity surface 61, and in this embodiment, the isolator 6 is located on the left side of the focusing lens 4. The isolator 6 is a one-way light-transmitting device, and blocks external light beams from entering the resonant cavity of the external cavity laser 100, so as to prevent the external light beams from affecting the laser effect in the resonant cavity, and simultaneously allow the laser generated in the resonant cavity to transmit outwards.

In this embodiment, the second cavity surface 61 is provided on a side of the separator 6 close to the focusing lens 4, that is, the second cavity surface 61 is provided on a right end surface of the separator 6 shown in the figure.

In other embodiments, the second cavity surface 61 may be a separate partial mirror, as long as the second cavity surface 61 and the focusing lens 4 are separately disposed.

The focusing lens 4 is located between the second cavity surface 61 and the first cavity surface 11 to focus the light from the gain chip 1 and the light reflected by the first cavity surface 11 onto the second cavity surface 61. The focusing lens 4 and the second cavity surface 61 are separately disposed, so that the optimal coupling of the laser light in the external cavity laser 100 can be realized. The focusing lens 4 and the isolator 6 have an air gap therebetween, and the focusing lens 4 focuses the light from the gain chip 1 and the light reflected by the first cavity surface 11 onto the second cavity surface 61 by adjusting the position of the focusing lens 4 to adjust the length of the air gap in the optical axis direction during assembly, thereby achieving optimal coupling of the laser light.

Because focusing lens 4 with have the air interval between isolator 6, focusing lens 4's focus is shorter, and the length of light path is shorter, reduces shared space from this, can make more miniature encapsulation, perhaps, can be used for saving space tunable filter 3, increaseing the interval between the internal device of tunable filter 3 to reduce the phenomenon of thermal crosstalk, in order to further promote tunable filter 3's dimming performance.

The coupling lens 7 is disposed on the downstream optical path of the isolator 6, and in this embodiment, the coupling lens 7 is disposed on the left side of the isolator 6. The laser output by the resonant cavity is transmitted outwards through the isolator 6 and is coupled through the coupling lens 7.

The housing 101 is provided with an electrical interface and an optical interface, the optical fiber 8 is disposed at the optical interface, the optical fiber 8 is disposed on a downstream optical path of the coupling lens 7, in this embodiment, the optical fiber 8 is disposed on a left side of the coupling lens 7, the coupling lens 7 is disposed in the accommodating cavity 102 of the housing of the external cavity laser 100 to the gain chip 1, the accommodating cavity 102 is a hermetically sealed cavity, the optical fiber 8 is coupled with the accommodating cavity 102 through the optical interface, and laser output by the resonant cavity is coupled to the optical fiber 8 through the coupling lens 7 and transmitted by the optical fiber 8.

Illustratively, the collimating lens 2 and the focusing lens 4 have the same optical axis.

In summary, in the present embodiment, the basic optical path of the light is: the gain chip 1 emits light, the light and the light reflected by the first cavity surface 11 are collimated by the collimating lens 2, then the light penetrates through the focusing lens 4, the focal point is converged on the second cavity surface 61, a part of the light is reflected from the focal point to resonate in the resonator, and the other part of the light is emitted outwards and passes through the isolator 6, the coupling lens 7 and the optical fiber 8 in sequence, so that the light-emitting coupling of the external cavity laser 100 is realized.

The focusing lens 4 may be any one of lenses, in this embodiment, the focusing lens 4 is preferably a lens with a small back intercept, and the focusing lens 4 is configured to couple with the second cavity surface 61, so that a focal point of the collimated light is located on the second cavity surface 61 to resonate in the resonant cavity. In this embodiment, in the assembly process, the two cavity surfaces of the resonant cavity, the gain chip, the collimating lens, and the like may be fixed first, so that the beam waist of the collimated light beam is located on the second cavity surface, and then the focusing lens 4 is adjusted to focus the light beam on the second cavity surface 61, so that the focal point of the focusing lens 4 is matched with the beam waist of the light beam collimated by the collimating lens 2, thereby ensuring the light output power of the resonant cavity.

The back intercept size of the focusing lens 4 adopted in the embodiment is smaller, and is easy to match with the beam waist of the collimated light beam, and meanwhile, the length of the section of the light path from the focusing lens to the second cavity surface is reduced by at least 30% compared with the prior art, so that the space occupied by the whole laser 100 can be further saved, and the miniaturization packaging is facilitated.

Since the focusing lens 4 is actively coupled, the focusing lens 4 itself is insensitive to thickness tolerances, which can be absorbed by the coupling, ensuring that the focal point of the focusing lens 4 falls on the second cavity surface 61. As can be seen from the above, the coupling tolerance of the focusing lens 4 is relatively large, and compared with the existing external cavity laser, the coupling tolerance of the external cavity laser 100 provided in this embodiment can be doubled, and the requirement on the processing precision of the focusing lens 4 is relatively low.

Illustratively, the semiconductor Cooler 9 (TEC) is located in the accommodating chamber 102, and the semiconductor Cooler 9 has a cooling function to reduce the temperature in the accommodating chamber 102.

The thermistor 10 is located in the accommodating cavity 102, in this embodiment, the thermistor 10 and the gain chip 1 are disposed adjacent to each other and are both disposed on a conductive substrate 110, and the conductive substrate 110 is fixed to the upper surface of the semiconductor refrigerator 9 through a base 111, that is, the thermistor 10 and the gain chip 1 are both disposed on the upper surface of the semiconductor refrigerator 9. The thermistor 10 is used for monitoring and feeding back the temperature in the accommodating cavity 102, particularly the temperature of the semiconductor gain chip, and cooperates with the semiconductor refrigerator 9 to enable the semiconductor gain chip to work in a relatively stable environment temperature. The collimating lens 2 is also fixed on the base 111, that is, the base 111 is disposed between the conductive substrate and the semiconductor cooler 9, and the base 111 plays a role in heat conduction and height adjustment. The base 111 is usually made of silicon materials, has a good heat conduction effect, and simultaneously raises the height of the collimating lens 2 and the height of the gain chip 1 through the base 111, and adjusts the light emitting height of the gain chip 1, so that the light emitting height can be consistent with the height of the adjustable filter 3, and the light passing height is further guaranteed to be consistent.

The technical effects of the external cavity laser in the embodiment are as follows: a second cavity surface 61 is arranged on one side of the isolator 6, a first cavity surface is arranged on one side of the gain chip 1, a resonant cavity is formed in a space between the second cavity surface and the first cavity surface, a focusing lens 4 is arranged in the resonant cavity, the focusing lens 4 and the second cavity surface 61 are respectively arranged in a separated mode, after light is coupled through the focusing lens 4, a focus falls on the second cavity surface 61, therefore, coupling tolerance is increased, light emitting of the accommodating cavity 102 is not influenced, space can be saved after a light path is shortened, or reduced space can be used for the adjustable filter 3, so that intervals among devices inside the adjustable filter 3 are increased, therefore, the phenomenon of thermal crosstalk is reduced, and the light modulation performance of the adjustable filter 3 can be improved.

Example 2

As shown in fig. 3 and 4, the present embodiment provides another external cavity laser 200, which includes a housing 201, wherein a containing cavity 202 is disposed in the housing 201, and the containing cavity 202 contains: the optical fiber laser comprises a gain chip 1, a second cavity surface 61, a first cavity surface 11, a focusing lens 4, a collimating lens 2, an adjustable filter 3, an optical monitoring assembly 5, an isolator 6, a coupling lens 7, an optical fiber 8, a semiconductor refrigerator 9 and a thermistor 10.

Compared with embodiment 1, the present embodiment is different in that, since the kind of the focusing lens 4 is not limited, the focusing lens 4 with a long rear intercept is used in the present embodiment, and the optical monitoring assembly 5 is disposed between the second cavity surface 61 and the focusing lens 4. At this time, the optical path between the second cavity surface 61 and the focusing lens 4 is multiplexed, further shortening the overall length of the resonant cavity.

Specifically, as in embodiment 1, the light monitoring assembly 5 includes a light monitoring detector 51 (MPD) and a light splitting sheet 52. In this embodiment, the light splitter 52 is disposed between the focusing lens 4 and the second cavity surface 61 to split the light in the resonant cavity into a main light beam with relatively large power and a sub-light beam with relatively small power, the main light beam resonates in the resonant cavity, and the sub-light beam is incident on the optical monitoring detector 51. Wherein the proportion of the sub-beams is 1-10%, preferably 2-5% in the embodiment.

Therefore, the external cavity laser disclosed by the utility model can adopt any lens as a cavity lens (focusing lens) in the resonant cavity, and the thickness tolerance of the cavity lens can be absorbed through coupling, so that the coupling tolerance of the resonant cavity is increased, and the space occupied by the resonant cavity is saved.

The external cavity laser provided by the embodiment of the present invention is described in detail above, and the principle and the embodiment of the present invention are explained in detail herein by applying specific examples, and the description of the above embodiments is only used to help understanding the method and the core idea of the present invention; meanwhile, for those skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims

1. An external cavity laser comprising a resonant cavity, said resonant cavity comprising a first facet and a second facet; a gain chip is arranged in the resonant cavity; the gain amplifier is characterized in that a focusing lens is arranged between the gain chip and the second cavity surface; the light beam emitted by the gain chip is converged on the second cavity surface through the focusing lens, and resonates between the first cavity surface and the second cavity surface; wherein a gap is formed between the focusing lens and the second cavity surface.

2. The external cavity laser of claim 1,

the external cavity laser further comprises a housing; the shell is internally provided with an accommodating cavity, and the resonant cavity, the gain chip and the focusing lens are arranged in the accommodating cavity.

3. The external cavity laser of claim 1, further comprising an isolator, said second facet being a lasing facet, said isolator being located in a laser optical path output by said second facet.

4. The external cavity laser of claim 3, wherein said second cavity facet is disposed on a face of said isolator adjacent to said resonant cavity;

or, the external cavity laser further includes a partial reflector, and the second cavity surface is located on the partial reflector.

5. The external cavity laser of claim 1,

the first cavity surface is arranged on one end surface of the gain chip far away from the focusing lens.

6. An external cavity laser as claimed in claim 1, wherein said laser further comprises a collimating lens and a tunable filter, said collimating lens and said tunable filter being disposed between said gain chip and said focusing lens, a light beam emitted from said gain chip being collimated by said collimating lens and then incident on said tunable filter, said tunable filter tuning a wavelength of laser light output from said external cavity laser.

7. The external cavity laser of claim 1, further comprising an optical monitoring component to monitor the optical efficiency of the external cavity laser.

8. The external cavity laser of claim 7, wherein the optical monitoring assembly includes an optical monitoring detector and a beamsplitter between the focusing lens and the second cavity surface, the beamsplitter splitting the light within the cavity into a primary beam that resonates within the cavity and a sub-beam that is incident within the optical monitoring detector.

9. An external cavity laser as claimed in claim 2 further comprising a coupling lens and an optical fiber, the housing providing an optical interface and an electrical interface; one end of the optical fiber is arranged in the optical interface; the coupling lens couples the laser light output from the resonant cavity into the optical fiber and transmits the laser light out of the external cavity laser through the optical fiber.

10. The external cavity laser of claim 1, further comprising a semiconductor refrigerator and a thermistor, said gain chip and said thermistor being disposed on said semiconductor refrigerator.