WO2024066048A1

WO2024066048A1 - Optical path coupling assembly and optical module having optical path coupling assembly

Info

Publication number: WO2024066048A1
Application number: PCT/CN2022/137493
Authority: WO
Inventors: 唐晓辉; 李晓娟; 董轲
Original assignee: 四川华岭光子科技有限公司
Priority date: 2022-09-28
Filing date: 2022-12-08
Publication date: 2024-04-04
Also published as: CN115437083A

Abstract

The invention discloses an optical path coupling assembly and an optical module having the optical path coupling assembly. The optical path coupling assembly comprises a collimating lens and a coupling lens which are oppositely arranged in space, and a polarization independent isolator arranged between the collimating lens and the coupling lens; a first segment of matched insertion core is arranged on one side close to the collimating lens; and a second segment of matched insertion core is arranged on one side close to the coupling lens. In the optical path coupling assembly and the optical module having the optical path coupling assembly provided in the present invention, a polarization independent system is used, thus solving the problem of unstable polarization states of a light source, and preventing the impact of reflected light; the two lenses are respectively located at two ends of the isolator, so that the coupling efficiency is improved; meanwhile, the optical path coupling assembly can select in practical uses different optical path structures for connection.

Description

Optical path coupling component and optical module with optical path coupling component

Technical Field

The present invention relates to the field of optical communication, and more specifically, to an optical path coupling component and an optical module with the optical path coupling component.

Background technique

In the optical communication industry, current optical modules all use linearly polarized laser output, which is then coupled into the optical fiber after passing through a lens and an isolator. The isolator must be polarization-dependent to ensure its performance. However, with the development of the industry, more and more problems of uncertain polarization states in the optical path have emerged. In this case, only polarization-independent devices can meet the requirements, especially in the coupling system of silicon photonic chips. The polarization state of light is uncertain, and a polarization-insensitive system must be used. However, the prior art does not involve polarization-insensitive optical path coupling components. After the linearly polarized light passes through the waveguide, the polarization state becomes disordered, and the original linear polarization device no longer meets the demand.

Summary of the invention

An object of the present invention is to solve at least the above-mentioned problems and/or disadvantages and to provide at least the advantages which will be described hereinafter.

In order to achieve these purposes and other advantages of the present invention, an optical path coupling assembly is provided, comprising:

Collimating lenses and coupling lenses arranged relatively in space;

A polarization-independent isolator is arranged between the collimating lens and the coupling lens;

Wherein, a first section of the insert core is provided on the side close to the collimating lens to match, and a second section of the insert core is provided on the side close to the coupling lens to match.

Preferably, the first section ferrule and the second section ferrule are configured as oblique end face ferrules or zero degree ferrules.

Preferably, when the first section of the ferrule is configured as a ferrule with an inclined end face, the end face of the ferrule is set to be an 8-degree inclined face.

Preferably, it further comprises a first connector for packaging the collimating lens and the polarization-independent isolator, and a second connector for packaging the coupling lens;

The connection method between the first connecting member and the second connecting member is configured to adopt a method of laser welding after alignment, or a method of gluing and fixing after nesting, so as to achieve the coupling of the collimated light path and the focused light path in space.

Preferably, when the first connecting member and the second connecting member are laser welded after alignment, the laser welding is achieved through a matching adjustment ring.

An optical module using an optical path coupling component comprises a receiving optical path and a transmitting optical path, wherein the transmitting optical path is configured to include:

A photodiode LD for generating outgoing light;

The backlight detector MPD and multiple modulators matched with the output end of LD,

A multiplexer that works with each modulator to combine multiple light beams into one

MUX; an amplifier SOA that amplifies the combined light beam and emits it;

Wherein, a matching optical path coupling component is provided between the MUX and the SOA;

In the receiving optical path, the optical path coupling component couples the received light into the silicon photonic chip, and then divides a beam of light into multiple beams with different wavelengths through the demultiplexer DEMUX and couples them into the photodiode PD. The optical path transmission in the receiving optical path is opposite to that of the transmitting optical path.

Preferably, when the emission light path is in forward propagation, the emitted divergent light is converted into parallel light through the collimating lens, and the polarization-independent isolator is equivalent to a parallel panel, which can make the parallel light propagate smoothly to the next optical component;

When there is reverse light propagation in the reflected light path, the polarization-independent isolator is equivalent to a Wollaston prism, and the reversely transmitted light O and E are deflected and cannot enter the collimating lens to continue transmission.

The present invention includes at least the following beneficial effects: the present invention mainly provides an optical path coupling component in a silicon photonic module, which adopts a polarization-independent system, which not only solves the problem of unstable polarization state of the light source, but also prevents the influence of reflected light; the two lenses are respectively located at both ends of the isolator to improve the coupling efficiency, and the optical path coupling component can be selected to be connected with different optical path structures in actual applications.

Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of an optical path coupling assembly in Embodiment 1 of the present invention;

FIG2 is a schematic diagram of the structure of an optical path coupling assembly in Embodiment 2 of the present invention;

FIG3 is a schematic diagram of the structure of an optical path coupling assembly in Embodiment 3 of the present invention;

FIG4 is a schematic diagram of the structure of an optical module using the optical path coupling assembly of the present invention;

FIG5 is a schematic diagram of a light path for forward propagation in emitted light;

FIG. 6 is a schematic diagram of the optical path for reverse propagation in the emitted light.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

It should be understood that terms such as “having”, “including” and “comprising” used herein do not specify the existence or addition of one or more other elements or combinations thereof.

It should be noted that in the description of the present invention, the orientation or positional relationship indicated by the term is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "sleeved/connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection through an intermediate medium. It can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

FIG1 shows an implementation form of an optical path coupling component according to the present invention, which includes: a collimating lens 1 and a coupling lens 2 which are symmetrically arranged in space;

A polarization-independent isolator 3 disposed between the collimating lens and the coupling lens;

Among them, a matching first section of ferrule 4 is arranged on the side close to the collimating lens, and a matching second section of ferrule 5 is arranged on the side close to the coupling lens. In this scheme, when coupling the products of the optical module, it is not only necessary to match the outgoing light, but also to consider the coupling efficiency of the optical path. This scheme designs a new type of optical coupling component for silicon photonic modules, with symmetrically placed lenses as collimators and couplers, an isolator is placed in the middle to reduce the influence of reflected light, and the isolator uses a polarization-independent isolator. In this scheme, since both ends of the optical path of the optical path coupling component Receptacle are ferrules, the collimating lens and the focusing lens are symmetrically placed, which reduces return loss and improves the optical path coupling efficiency. At the same time, because the isolator selected in this scheme is a polarization-independent isolator, the problem of uncertain polarization state of the light-emitting chip is solved, and the optical chip is prevented from being damaged by the reflection of the optical path.

It can be seen that the present invention is aimed at the optical path coupling structure of the optical device in the silicon photonic module. The optical path coupling process is simple and easy to operate. The entire Receptacle is connected to the FA through a standard single-mode optical fiber, and the optical path coupling is directly performed at the light output position of the silicon photonic chip. The coupling efficiency is high, the return loss is low, and it is independent of the polarization state of the light source and is polarization insensitive. In actual applications, the optical path coupling component is mainly composed of passive components, including: a collimating lens, a polarization-independent isolator (birefringent crystal and Faraday crystal), a focusing lens, a first section of the core, and a second section of the core. According to different application scenarios, it can be divided into the following two schemes:

Embodiment 1:

If the light-emitting chip in the optical module is a silicon photonic chip structure, and the silicon photonic chip emits a certain angle of light, in order to improve the optical coupling efficiency, the end face of the fiber array FA is cut to match the angle. The structure of the entire optical path coupling component Receptacle is composed of passive devices as shown in Figure 1, in which the first section of the core is an inclined 8-degree core to compensate for the optical axis offset caused by the polarization-independent isolator and reduce the reflected light at the end face of the core. It can directly align the required coupling beam, and then pass through the collimating lens to form parallel light to couple into the polarization-independent isolator, and finally focus and couple to the second section of the core by the focusing lens. The second section of the core is a 0° core, and the pigtail is connected through the second section of the core to complete the light transmission. When the collimating lens and the focusing lens are coupled, laser welding is performed through the adjustment ring, which has high reliability. In this scheme, the optical component coupling package in the silicon photonic module is mainly considered, which not only meets the assembly requirements of the optical module, but also considers the problem of laser polarization state, and also reduces the loss of coupling energy, which is suitable for the market demand of optical module packaging. At the same time, because the end face of the first section of the core is an inclined end face, it compensates for the offset of the isolator optical axis and reduces the influence of reflected light, thereby improving the coupling efficiency.

Embodiment 2:

To save costs, the shape of the entire Receptacle structure remains unchanged, and the coupling method of the collimating lens and the focusing lens can be fixed by glue, as shown in Figure 2, so that the entire contact area is nested with each other and the glue overflows the surface. The rest of the structure remains unchanged referring to Scheme 1.

Example 3

If the outgoing light beam is a normal light beam, it can be directly coupled through the Receptacle structure and aligned and coupled using the method of Example 1 or Example 2.

Example 4

The entire Receptacle structure can be aligned with the light output position of the silicon photonic chip, as shown in Figure 3. It is coupled through FA 8 in the middle and enters the standard single-mode optical fiber 9 (G657.B3). The optical fiber is then fixed by glue and coupled to the 8-degree ferrule. It passes through the collimating lens, polarization-independent isolator, focusing lens, and finally enters the 0-degree ferrule to connect the pigtail transmission. In actual applications, in order to improve the FA yield, the fiber coating is removed, and the optical fiber is fixed with a glass capillary with an aperture of 0.127 mm. In addition, the entire Receptacle part is fixed during the coupling process so that the FA is aligned with the light output port of the silicon photonic chip for coupling and fixed by glue.

Furthermore, it also includes a first connector for packaging the collimating lens and the polarization-independent isolator, and a second connector for packaging the coupling lens;

Wherein, in embodiment 1, the connection method between the first connecting member and the second connecting member is configured to adopt a method of laser welding after alignment;

In Example 2, the connection method of the first connecting member and the second connecting member is configured to be fixed by gluing after being nested, so as to achieve the coupling of the collimated light path and the focused light path in space.

Furthermore, the Receptacle structure of the present invention is not limited to connecting FA, but can also be aligned with the coupling light beam in other ways; the lens selection is not limited to aspheric lenses, but can be adjusted according to the optical path design; in addition, the lens adjustment ring facilitates coupling with the optical path and fixing the lens, which will be discussed in detail according to the specific usage method; the present invention involves two sections of ferrules, and the coupling efficiency can also be improved by increasing the end face angle or coating according to actual usage.

The optical path coupling component of the present invention is mainly aimed at the optical path coupling part in the silicon photonic module. Since the optical path in the silicon photonic chip is transmitted through a waveguide and then passes through an optical fiber during optical path coupling, the polarization state of the laser is uncertain. Therefore, this factor needs to be considered during optical path coupling. The overall silicon photonic module design diagram is shown in Figure 4. The TX transmitting end module and the RX receiving end module silicon photonic chip are located on the PCB board, wherein the TX end emits light through the laser LD, a part of which is received by the backlight detector MPD to indirectly observe the LD light emission, and another part of the laser is modulated by the modulator in turn, and then the multiplexer MUX merges the 4 light beams into one laser coupling, and then amplifies and emits through the SOA amplifier. The optical path coupling component in this scheme not only meets the assembly requirements of the optical module, but also takes into account the problem of laser polarization state, and also reduces the loss of coupling energy, which is suitable for the market demand for optical module packaging.

The polarization-independent system designed by the present invention does not rely on the influence of the polarization state of the light source. Taking the TX end as an example, the forward light path is shown in FIG5 . During forward propagation, when the divergent light is changed into parallel light through the collimating lens, the polarization-independent isolator is equivalent to a parallel panel, and the light path is smoothly propagated to the next optical component. When there is reverse light propagation in the light path, as shown in FIG6 , the polarization-independent isolator is equivalent to a Wollaston prism, and the reversely transmitted light O light and E light are deflected and cannot enter the lens to continue transmission.

The RX end transmits through any of the Receptacle structures in the above schemes, which is opposite to the optical path of the TX end, and then is coupled into the silicon photonic chip through single-mode optical fiber and FA. The DEMUX divides a laser beam into lasers with different wavelengths and couples them to the photodiode PD.

The above solution is only an illustration of a preferred embodiment, but is not limited thereto. When implementing the present invention, appropriate replacement and/or modification can be performed according to user needs.

The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized. Therefore, without departing from the general concept defined by the claims and equivalent scope, the present invention is not limited to the specific details and the illustrations shown and described here.

Claims

An optical path coupling component, characterized by comprising:

Collimating lenses and coupling lenses arranged relatively in space;

A polarization-independent isolator is arranged between the collimating lens and the coupling lens;

Wherein, a first section of the insert core is provided on the side close to the collimating lens to match, and a second section of the insert core is provided on the side close to the coupling lens to match.
The optical path coupling assembly according to claim 1, characterized in that the first section ferrule and the second section ferrule are configured as oblique end face ferrules or zero degree ferrules.
The optical path coupling assembly as described in claim 2 is characterized in that when the first section of the ferrule is configured as a beveled end face ferrule, the end face of the ferrule is set to an 8-degree bevel.
The optical path coupling assembly according to claim 1, characterized in that it also includes a first connector for packaging the collimating lens and the polarization-independent isolator, and a second connector for packaging the coupling lens;

The connection method between the first connecting member and the second connecting member is configured to adopt a method of laser welding after alignment, or a method of gluing and fixing after nesting, so as to achieve the coupling of the collimated light path and the focused light path in space.
The optical path coupling assembly as described in claim 1 is characterized in that when the first connecting member and the second connecting member are laser welded after alignment, laser welding is achieved through a matching adjustment ring.
An optical module using the optical path coupling assembly according to any one of claims 1 to 5, comprising a receiving optical path and a transmitting optical path, wherein the transmitting optical path is configured to include:

A photodiode LD for generating outgoing light;

The backlight detector MPD and multiple modulators matched with the output end of LD,

A multiplexer MUX cooperates with each modulator to combine multiple light beams into one beam;

An amplifier SOA that amplifies the combined light beam and emits it;

Wherein, a matching optical path coupling component is provided between the MUX and the SOA;

In the receiving optical path, the optical path coupling component couples the received light into the silicon photonic chip, and then divides a beam of light into multiple beams with different wavelengths through the demultiplexer DEMUX and couples them into the photodiode PD. The optical path transmission in the receiving optical path is opposite to that of the transmitting optical path.
The optical module as claimed in claim 6 is characterized in that when the emission light path is in forward propagation, the emitted divergent light is converted into parallel light by the collimating lens, and the polarization-independent isolator is equivalent to a parallel panel, which can make the parallel light propagate smoothly to the next optical component;

When there is reverse light propagation in the reflected light path, the polarization-independent isolator is equivalent to a Wollaston prism, and the reversely transmitted light O and E are deflected and cannot enter the collimating lens to continue transmission.