Multi-wavelength laser and router with fast switching of output wavelength and port

Abstract

The application relates to a multi-wavelength laser and a router with fast switching of output wavelengths and ports. The technical scheme adopted by the application is as follows: a multi-wavelength laser has an NxN in-cavity wavelength router, any pair of input and output port combinations of which has minimum loss at a certain specific wavelength; a port selection semiconductor optical amplifier has N inputs corresponding to the inputs of the in-cavity wavelength router, one end of the optical amplifier is made into a high reflection or partial reflection surface, and the other end is connected to the input of the in-cavity wavelength router; a wavelength selection semiconductor optical amplifier has N outputs corresponding to the outputs of the in-cavity wavelength router, one end of the optical amplifier is connected to the output of the in-cavity wavelength router, and the other end is provided with a partial reflector; an optical resonant cavity of a certain specific wavelength is formed between the reflection surface of any port selection semiconductor optical amplifier and the partial reflector of any wavelength selection semiconductor optical amplifier.

Description

Technical Field

[0001] This invention relates to a multi-wavelength laser and a router whose output wavelength and port can be quickly switched. It is applicable to the field of semiconductor optical emission router technology. Background Technology

[0002] The rapid growth of data center network traffic requires more efficient interconnection methods. Currently, various all-optical interconnection network architectures have been realized based on tunable lasers, passive wavelength routers, optical switches, etc., which have advantages such as high bandwidth, low cost, low power consumption and low latency.

[0003] In existing technologies, one network architecture is a distributed optical switching network based on tunable laser transmitters and cyclic wavelength routers. This architecture places a cyclic wavelength router at each transmitting / receiving node as a multiplexer / demultiplexer, enabling direct connections between different nodes without optical-to-electrical-to-optical conversion. A single link can use N wavelengths for simultaneous transmission, thus increasing the bandwidth of the link between any two nodes to N times the bandwidth of a single channel. The switching speed of this optical switching technology depends on the wavelength switching speed of the tunable laser. Chips using carrier plasma effects can achieve switching speeds of less than 10 ns, while chips based on current-injected thermo-optical effects have switching speeds on the order of 20-100 μs.

[0004] At the 2020 SIGCOMM conference, Microsoft introduced another planar optically switched data center network called Sirius, titled "Sirius: A flat datacenter network with nanosecond optical switching." It uses tunable lasers with nanosecond switching speeds and cyclic array waveguide grating routers to achieve extremely low-latency optical interconnects. However, only one wavelength is transmitted between nodes, limiting its bandwidth. Furthermore, switching each channel requires multi-electrode control, making the system complex and placing high demands on scheduling, synchronization, and control algorithms. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a multi-wavelength laser and a router whose output wavelength and port can be quickly switched, in view of the above-mentioned problems.

[0006] The technical solution adopted in this invention is: a multi-wavelength laser, characterized in that it has:

[0007] An NxN intracavity wavelength router has minimal loss for any pair of input / output ports at only one specific wavelength.

[0008] The port selection semiconductor optical amplifier has N ports, each corresponding to one of the input terminals of the intracavity wavelength router. One end of the optical amplifier is made into a highly reflective or partially reflective surface, and the other end is connected to the input terminal of the intracavity wavelength router.

[0009] A wavelength-selective semiconductor optical amplifier has N units, each corresponding to the output of an in-cavity wavelength router. One end of the optical amplifier is connected to the output of the in-cavity wavelength router, and the other end is equipped with a partial reflector.

[0010] An optical resonant cavity with a specific wavelength is formed between the reflector of any port-selectable semiconductor optical amplifier and the partial reflector of any wavelength-selectable semiconductor optical amplifier.

[0011] By applying current to the port-selective semiconductor optical amplifier and the wavelength-selective semiconductor optical amplifier corresponding to any pair of input-output ports of the intracavity wavelength router, laser light of a specific wavelength corresponding to the input-output port combination is output at part of the reflector end of the corresponding optical resonant cavity.

[0012] The intracavity wavelength router is a cyclic wavelength router, and the channel spacing of its N channels is 1 / N of the entire free spectrum range of the wavelength router.

[0013] The intracavity wavelength router is a cyclic etching diffraction grating router.

[0014] The intracavity wavelength router is a cyclic array waveguide grating router.

[0015] A router whose output wavelength and port can be quickly switched is characterized by having:

[0016] The cavity laser employs the aforementioned multi-wavelength laser;

[0017] The modulator has N units, each connected to a corresponding laser output terminal of the multi-wavelength laser, and is used to modulate the laser output of the multi-wavelength laser.

[0018] An external wavelength router has its input end connected to N modulators in a one-to-one correspondence, and is used to route laser light of a specific wavelength modulated by the modulator to the corresponding output end of the external wavelength router based on the input end and wavelength.

[0019] The external wavelength router has the same structure as the internal wavelength router in the multi-wavelength laser and is placed in mirror image of the internal wavelength router. The input end of the external wavelength router corresponds to the output end of the internal wavelength router, and the output end of the external wavelength router corresponds to the input end of the internal wavelength router.

[0020] It also has:

[0021] There are N signal gain semiconductor optical amplifiers, each connected to a corresponding output terminal of the external wavelength router.

[0022] The output end of the signal gain semiconductor optical amplifier is coated with a high-transparency film.

[0023] By applying current to a port-selective semiconductor optical amplifier and one or more wavelength-selective semiconductor optical amplifiers, a multi-wavelength laser can output one or more specific wavelength lasers corresponding to the corresponding input-output port combinations on the intracavity wavelength router.

[0024] One or more specific wavelength lasers output from a multi-wavelength laser are modulated by a modulator and then routed by an external wavelength router to the output terminal corresponding to the selected semiconductor optical amplifier at a certain port.

[0025] The corresponding output of the external wavelength router contains one or more modulated lasers of a specific wavelength, which are amplified by a signal gain semiconductor optical amplifier before being output.

[0026] The beneficial effects of this invention are as follows: By setting a reflective surface at one end of the port-selective semiconductor optical amplifier and a partial reflector at one end of the wavelength-selective semiconductor optical amplifier, and in conjunction with the intracavity wavelength router, NxN optical resonant cavities are formed. Since any pair of input and output ports of the intracavity wavelength router has minimal loss only at a specific wavelength, each optical resonant cavity can only emit laser light of the corresponding wavelength of the corresponding input and output port combination. Moreover, the specified wavelength of laser light can be quickly output simply by turning on the port-selective semiconductor optical amplifier and the wavelength-selective semiconductor optical amplifier.

[0027] This invention enables a multi-wavelength laser to simultaneously output multiple lasers of different wavelengths by applying current to any port-selectable semiconductor optical amplifier and multiple wavelength-selectable semiconductor optical amplifiers.

[0028] This invention modulates a specific wavelength laser output from a multi-wavelength laser using a modulator, routes the laser to a specified output terminal using an external wavelength router based on the laser's input terminal and wavelength, and can also combine multiple specific wavelength lasers received simultaneously from multiple input terminals by routing them to the same output terminal based on the input terminal and wavelength.

[0029] In this invention, the external wavelength router has the same structure as the internal wavelength router in the multi-wavelength laser and is placed in mirror image of the internal wavelength router, so that one or more wavelengths of light excited by any port-selected semiconductor optical amplifier can be output from the output port of the external wavelength router corresponding to the semiconductor optical amplifier of that port selection.

[0030] The wavelength and channel switching of the router in this invention are both achieved by switching on and off a semiconductor optical amplifier. The switching speed is determined by the response time of the semiconductor optical amplifier turning on and off. Taking the port selection semiconductor optical amplifier as an example, its switching time between turning on and off is less than 1 ns. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of an embodiment.

[0032] Figure 2 This is a diagram illustrating the wavelength selection principle of the wavelength router in the embodiment.

[0033] Figure 3 This is a diagram illustrating the principle of output wavelength and port switching in an example.

[0034] Figure 4 This is a schematic diagram of a wavelength router for etching diffraction gratings.

[0035] Figure 5 This is a schematic diagram of an arrayed waveguide grating wavelength router.

[0036] Figure 6 This is a schematic diagram of an embodiment (using a cyclic etched diffraction grating router).

[0037] Figure 7 The above is a superimposed image of the single-wavelength output spectrum obtained after selecting the first port of the semiconductor optical amplifier and different wavelength-selective semiconductor optical amplifiers in the embodiment.

[0038] Figure 8 The above is a superimposed image of the single-wavelength output spectrum obtained after selecting the third port of the semiconductor optical amplifier and different wavelength-selective semiconductor optical amplifiers in the embodiment.

[0039] Figure 9 The image shows the multi-wavelength output spectrum excited by the semiconductor optical amplifier selected at the third port in this embodiment.

[0040] Figure 10 The diagram shows the effect of selecting the semiconductor optical amplifier to turn on and off at the third port in the embodiment.

[0041] 1. Port-selective semiconductor optical amplifier; 2. In-cavity wavelength router; 3. Wavelength-selective semiconductor optical amplifier; 4. Modulator; 5. Out-of-cavity wavelength router; 6. Signal-gain semiconductor optical amplifier; 7. Wavelength router input port; 8. Etched diffraction grating; 9. Wavelength router output port; 10. Star coupler; 11. Arrayed waveguide. Detailed Implementation

[0042] like Figure 1As shown, this embodiment provides a multi-wavelength transmitter router whose output wavelength and port can be quickly switched, consisting of an internal cavity laser and an external cavity router.

[0043] In this example, the intracavity laser is a multi-wavelength laser with an NxN intracavity wavelength router, N port-selectable semiconductor optical amplifiers, and N wavelength-selectable semiconductor optical amplifiers. Any pair of input and output ports of the total intracavity wavelength router has minimal loss only at a specific wavelength.

[0044] In this embodiment, the N port-selectable semiconductor optical amplifiers are connected one-to-one with the N input terminals of the intracavity wavelength router. One end of the port-selectable semiconductor optical amplifier is a reflective surface coated with a high-reflectivity film, and the other end is connected to one input terminal of the intracavity wavelength router.

[0045] N wavelength-selective semiconductor optical amplifiers are connected one-to-one with the N output terminals of the intracavity wavelength router. One end of the wavelength-selective semiconductor optical amplifier is connected to one output terminal of the intracavity wavelength router, and the other end is equipped with a partial reflector.

[0046] In this embodiment, any port-selectable semiconductor optical amplifier and any wavelength-selectable semiconductor optical amplifier are combined with an in-cavity wavelength router to form an optical resonant cavity.

[0047] This embodiment provides optical gain by applying current to any port-selective semiconductor optical amplifier and any wavelength-selective semiconductor optical amplifier, enabling the output of laser light of a wavelength corresponding to the input / output port combination of the intracavity wavelength router. By simultaneously operating the any port-selective semiconductor optical amplifier and multiple wavelength-selective semiconductor optical amplifiers, laser light of a wavelength corresponding to the input / output port combination of the intracavity wavelength router can be output from these multiple wavelength-selective semiconductor optical amplifiers. In this example, switching between different wavelength-selective semiconductor optical amplifiers allows for switching the output wavelength.

[0048] Taking a six-channel intracavity laser as an example, Figure 2 After selecting the third port for the selective semiconductor optical amplifier, the loss spectrum reaches the array of different wavelength-selective semiconductor optical amplifiers after passing through the intracavity wavelength router. It can be seen that after selecting the port for the selective semiconductor optical amplifier, different wavelengths can be selected by different wavelength-selective semiconductor optical amplifiers, and this wavelength is automatically aligned with the intracavity wavelength router. Simultaneous activation of multiple wavelength-selective semiconductor optical amplifiers can achieve simultaneous output of multiple wavelengths.

[0049] In this embodiment, the external cavity router includes N modulators, an NxN external cavity wavelength router, and N signal gain semiconductor optical amplifiers. The structure is the same as that of the internal cavity wavelength router in a multi-wavelength laser, and it is placed in mirror image of the internal cavity wavelength router. The input terminals of the external cavity wavelength router correspond one-to-one with the output terminals of the internal cavity wavelength router, and the output terminals of the external cavity wavelength router correspond one-to-one with the input terminals of the internal cavity wavelength router.

[0050] In this example, N modulators are connected one-to-one with the N partial reflectors of the internal cavity laser to modulate the laser of different wavelengths output by the internal cavity laser; the N modulators are also connected one-to-one with the N input terminals of the external cavity wavelength router, which routes the laser modulated by the modulators to the corresponding output terminal of the external cavity wavelength router according to the input terminal and wavelength.

[0051] Since the external wavelength router and the internal wavelength router have the same structure and are arranged in a mirror image in this embodiment, the laser of one or more wavelengths excited by the semiconductor optical amplifier selected by a port on a certain input terminal of the internal wavelength router will be routed to the output terminal of the external wavelength router corresponding to a certain input terminal of the internal wavelength router after passing through the external wavelength router.

[0052] In this embodiment, N signal gain semiconductor optical amplifiers correspond one-to-one with the N output terminals of the external wavelength router. One end of the signal gain semiconductor optical amplifier is connected to one output terminal of the external wavelength router, and the other end of the signal gain semiconductor optical amplifier serves as one output terminal of the multi-wavelength transmitting router. The signal gain semiconductor optical amplifier is used to amplify the signal output by the external wavelength router.

[0053] In this example, to prevent additional resonance from forming in the external cavity router, a high-transmittance film is coated on the transmission surface of the output end of the signal gain semiconductor optical amplifier.

[0054] The wavelength and port switching principle of a multi-wavelength optical transmitter router is achieved through... Figure 3 To illustrate, taking a six-channel transmitting router as an example, for a single port-selective semiconductor optical amplifier, after passing through a 6×6 intracavity wavelength router, it can excite six wavelengths of light together with six wavelength-selective semiconductor optical amplifiers, the wavelengths of which are denoted by λ. ij This indicates that 'i' represents the port selection semiconductor optical amplifier number, and 'j' represents the wavelength number. For example... Figure 3 As shown, the first port is selected to select the semiconductor optical amplifier, whose lasing wavelength is λ. 11 ,λ 12 ,λ 13 ,λ 14 ,λ 15 ,λ 16These correspond to the 5th, 6th, 1st, 2nd, 3rd, and 4th wavelength-selective semiconductor optical amplifiers, respectively. After being routed by the 6×6 external wavelength router, since the two wavelength routers inside and outside the cavity are symmetrical, the light of these six wavelengths will all be routed to the 1st signal gain semiconductor optical amplifier for output.

[0055] Choosing different wavelengths allows the semiconductor optical amplifier to output different wavelengths; wavelength switching can be achieved by switching the wavelength-selective semiconductor optical amplifier.

[0056] Similarly, the third port is selected as the semiconductor optical amplifier, whose lasing wavelength is λ. 31 ,λ 32 ,λ 33 ,λ 34 ,λ 35 ,λ 36 These correspond to the 1st, 2nd, 3rd, 4th, 5th, and 6th wavelength-selective semiconductor optical amplifiers, respectively. After being routed through a 6×6 external cavity wavelength router, they are routed to the 3rd gain semiconductor optical amplifier for output.

[0057] In this embodiment, all wavelengths excited by the i-th port-selective semiconductor optical amplifier will be routed to the i-th gain semiconductor optical amplifier for output. In this way, by switching different port-selective semiconductor optical amplifiers and simultaneously switching the corresponding gain semiconductor optical amplifier, the port switching function can be realized.

[0058] In this example, both the intracavity wavelength router and the extracavity wavelength router should be cyclic wavelength routers. That is, for an N×N wavelength router, the channel spacing of its N channels is designed to be 1 / N of the entire free spectrum range of the wavelength router. This ensures that all wavelengths excited by the semiconductor optical amplifier selected at any port cycle through the same N wavelengths.

[0059] In this embodiment, one implementation of the intracavity wavelength router and the extracavity wavelength router is a cyclic etching diffraction grating router, the structural schematic of which is shown below. Figure 4 As shown, a wavelength router consists of an input port, an etched diffraction grating, and an output port. The basic design of the cyclic etched diffraction grating router is based on the Rowland circle theory. The grating is located on a large circle of radius R, and the input and output points are located on a small circle of radius R / 2. Light of a specific wavelength incident from an input port is reflected by multiple teeth of the grating and then focused by diffraction at an output port. This ensures minimal loss for any pair of input and output ports where only one wavelength of light is present.

[0060] In this embodiment, another implementation of the intracavity wavelength router and the extracavity wavelength router is a cyclic array waveguide grating, the structural schematic of which is shown below. Figure 5As shown, a wavelength router consists of an input port, an output port, a star coupler, and an array waveguide. Light of a specific wavelength incident from one input port propagates freely within the star coupler and then enters the array waveguide, which is composed of multiple waveguides of different lengths. The phase shift of the light after passing through the array waveguide varies, and after passing through another star coupler, interference imaging occurs at a specific output port. This also allows for minimal loss when only one wavelength of light is present for any pair of input and output ports.

[0061] In this example, the modulator can achieve high-speed modulation of optical signals. One implementation method is an electroabsorption modulator array, and another implementation method is a Mach-Zehnder modulator array.

[0062] Figure 6 This is a schematic diagram illustrating the specific design structure of one implementation of the multi-wavelength transmitter router in this embodiment. The intracavity wavelength router and the extracavity wavelength router are two symmetrically placed cyclically etched diffraction gratings. The wavelength selection semiconductor optical amplifier and the modulator are connected through an on-chip partial reflector, which can be fabricated using a deep etch groove.

[0063] according to Figure 6 The device was fabricated using the design method. After selecting the first port for the semiconductor optical amplifier, different wavelength-selective semiconductor optical amplifiers were selected, and their single-wavelength output spectrum superposition diagrams were measured as shown in the figure. Figure 7 As shown in the figure. After selecting the third port to select the semiconductor optical amplifier, different wavelengths of the semiconductor optical amplifier were selected, and the superimposed single-wavelength output spectra were measured as follows. Figure 8 As shown. Each output channel can achieve single-wavelength output, and the output wavelength can be switched between the same six wavelengths.

[0064] In this embodiment, after selecting the third port for the semiconductor optical amplifier, current is applied to all wavelength-selective semiconductor optical amplifiers, and the simultaneous multi-wavelength output spectrum is measured as follows: Figure 9 As shown, each channel can achieve multi-wavelength output with the same six wavelengths.

[0065] In this example, the multi-wavelength optical transmitting router switches both wavelengths and channels via the switching of semiconductor optical amplifiers. The switching speed is determined by the response time of the semiconductor optical amplifiers when they are turned on and off. Taking the semiconductor optical amplifier selected on the third port as an example, its response time for turning on and off is as follows: Figure 10 As shown, the switching speed is less than 1 ns.

[0066] The working principle of the multi-wavelength transmission router in this embodiment is as follows:

[0067] Determine the optical signal output terminal and wavelength of the multi-wavelength transmitting router based on signal transmission requirements;

[0068] Select a semiconductor optical amplifier and one or more wavelength-selectable semiconductor optical amplifiers based on the optical signal output terminal and wavelength.

[0069] By applying current to the corresponding port-selective semiconductor optical amplifier and wavelength-selective semiconductor optical amplifier, the multi-wavelength laser can output one or more specific wavelength lasers corresponding to the corresponding input / output port combinations on the intracavity wavelength router.

[0070] One or more specific wavelength lasers output from a multi-wavelength laser are modulated by a modulator and then routed by an external wavelength router to the output terminal corresponding to the corresponding port-selected semiconductor optical amplifier.

[0071] The corresponding output of the external wavelength router contains one or more modulated lasers of a specific wavelength, which are amplified by a signal gain semiconductor optical amplifier before being output.

[0072] In this embodiment, the multi-wavelength optical transmitter router can be integrated on the same substrate. The port selection semiconductor optical amplifier array, the wavelength selection semiconductor optical amplifier array, and the signal gain semiconductor optical amplifier array are fabricated on active materials that can provide optical gain. The external-cavity wavelength router and the internal-cavity wavelength router are fabricated on passive materials with low optical loss. The modulator array is fabricated on active materials that can achieve high-speed electro-optic modulation.

[0073] One integration approach in this example is InP-based monolithic integration. Through techniques such as quantum well hybridization, end-to-end bonding, and selective epitaxy, different regions on the same substrate can possess different material properties. Another integration approach is hybrid integration. Regions providing optical gain can be fabricated using InP-based quantum well materials. Regions providing wavelength routing can be fabricated using materials such as silicon-on-insulator (SOI), silicon nitride (Si3N4), and silicon oxide (SiO2). The modulator array region can be fabricated using InP-based materials, doped SOI, and lithium niobate (LiNbO3). Different devices are then integrated onto the same substrate using heterogeneous integration.

Claims

1. A router whose output wavelength and port can be quickly switched, characterized in that, have: The internal cavity laser employs a multi-wavelength laser. An NxN external cavity wavelength router has its input terminal connected to the laser output terminal of the multi-wavelength laser in a one-to-one correspondence, and is used to route the laser to the corresponding output terminal of the external cavity wavelength router based on the input terminal and wavelength. The multi-wavelength laser has the following characteristics: An NxN intracavity wavelength router has minimal loss for any pair of input / output ports at only one specific wavelength. The port selection semiconductor optical amplifier has N ports, each corresponding to one of the input terminals of the intracavity wavelength router. One end of the optical amplifier is made into a highly reflective or partially reflective surface, and the other end is connected to the input terminal of the intracavity wavelength router. The wavelength-selective semiconductor optical amplifier has N units, each corresponding to one of the output terminals of the intracavity wavelength router. One end of the optical amplifier is connected to the output terminal of the intracavity wavelength router, and the other end is equipped with a partial reflector. An optical resonant cavity with a specific wavelength is formed between the reflective surface of any port-selectable semiconductor optical amplifier and the partial reflector of any wavelength-selectable semiconductor optical amplifier. By applying current to a port-selective semiconductor optical amplifier and one or more wavelength-selective semiconductor optical amplifiers, a multi-wavelength laser outputs one or more specific wavelengths of laser light corresponding to the corresponding input / output port combination on the intracavity wavelength router. The laser light is then routed by the external wavelength router to the output terminal of the external wavelength router corresponding to the port-selective semiconductor optical amplifier. By switching different wavelengths, the semiconductor optical amplifier can be selected to switch the output wavelength. Switching between different ports allows for the selection of semiconductor optical amplifiers, thus enabling port switching.

2. The router with fast switching capability for both output wavelength and port as described in claim 1, characterized in that: The intracavity wavelength router is a cyclic wavelength router, and the channel spacing of its N channels is 1 / N of the entire free spectrum range of the wavelength router.

3. The router with fast switching capability for both output wavelength and port as described in claim 2, characterized in that: The intracavity wavelength router is a cyclic etching diffraction grating router.

4. The router with fast switching capability for both output wavelength and port as described in claim 2, characterized in that: The intracavity wavelength router is a cyclic array waveguide grating router.

5. The router with fast switching capability for both output wavelength and port as described in claim 1, characterized in that, Also includes: N modulators are placed between the output of the NxN intracavity wavelength router and the input of the NxN extracavity wavelength router, and are connected one-to-one with the laser output terminal of the multi-wavelength laser to modulate the laser output of the multi-wavelength laser.

6. The router with fast switching capability for both output wavelength and port as described in claim 1, characterized in that: The external wavelength router has the same structure as the internal wavelength router in the multi-wavelength laser and is placed in mirror image of the internal wavelength router. The input end of the external wavelength router corresponds to the output end of the internal wavelength router, and the output end of the external wavelength router corresponds to the input end of the internal wavelength router.

7. The router with fast switching capability for both output wavelength and port as described in claim 1, characterized in that, It also has: There are N signal gain semiconductor optical amplifiers, each connected to a corresponding output terminal of the external wavelength router.

8. The router with fast switching capability for both output wavelength and port as described in claim 7, characterized in that: The output end of the signal gain semiconductor optical amplifier is coated with a high-transparency film.

9. The router with fast switching capability for both output wavelength and port as described in claim 1, characterized in that: The router is integrated on the same substrate, which contains both active and passive materials. It is fabricated monolithically on an InP substrate, and different regions on the same substrate have different material properties through quantum well hybridization, end docking, and selective epitaxy.

10. The router with fast switching capability for both output wavelength and port according to claim 1, characterized in that: The router is integrated on the same substrate. The region on the substrate that provides optical gain is made of InP-based quantum well material, the region that provides wavelength routing is made of silicon-on-insulator, silicon nitride, or silicon oxide, and the modulator array region is made of InP-based material, doped SOI, or lithium niobate.

Images