Optical device

Abstract

The present disclosure realizes optical devices with diverse connection configurations by means of a single type of optical device. The present disclosure provides an optical device in which an optical transmitter including a plurality of optical modulators and an optical receiver including a plurality of photodetectors are integrated on a chip substrate, wherein optical signal inputs / outputs to / from the optical transmitter and optical signal inputs to the optical receiver are integrated on one side edge of the chip substrate and also integrated on the opposite side edge across from the one side edge.

Description

Optical Devices

[0001] The present invention relates to an optical device, and more particularly to an optical device having an optical transmitter including a plurality of optical modulators and an optical receiver including a plurality of photodetectors.

[0002] Development of optical engines, in which optical and electronic devices are mounted on the same substrate, is progressing. An optical engine is an optical transceiver module that consists of an optical device based on silicon photonics technology and an electronic device for optical communication (PHY), both of which are mounted on the same substrate.

[0003] FIG. 1 shows the configuration of a conventional optical engine module. Optical engine module 10 is composed of multiple PHYs 11a and 11b and multiple optical devices 12a and 12b. The optical devices are connected to optical fibers 14a and 14b via fiber arrays (FA) 13a and 13b. Optical engine module 10 is mounted on a printed circuit board (PCB) 15 via a socket. In the configuration shown in FIG. 1, the optical fiber is schematically shown as a single line, but an optical circuit is generally provided with multiple optical input / output ports, and the optical fibers are also provided in the same number as the ports.

[0004] Figure 2 shows the configuration of a conventional optical transceiver. This is an example of an optical transceiver 20 that transmits and receives optical signals using four parallel SMFs (see, for example, Non-Patent Document 1). On the transmitting side, continuous wave (CW) light output from a laser diode (LD) 23 is modulated in an optical modulator in an optical transmitter (TX) 24 using an electrical signal supplied via a driver circuit 22 from a DSP chip 21 that performs signal processing. The transmitted optical signal is then supplied to a connector 25 consisting of an FA connected to the SMF. On the receiving side, the received optical signal from the SMF is received by an optical receiver (RX) 26, converted into an electrical signal, amplified by an amplifier (TIA) 27, and supplied to the DSP chip 21. In the conventional optical transceiver 20, the TX 24 and RX 26, which are optical devices in the optical system, are integrated into a photonic integrated circuit (PIC) 30 called a PE (Photonic Engine).

[0005] FIG. 3 shows the configuration of a PIC in a conventional optical transceiver. This is an example of an optical transceiver 20 that transmits and receives optical signals using four parallel SMFs. Only the main components of the optical components constituting the optical transmitter 24 and optical receiver 26 in the PIC 30 are illustrated. The optical transmitter 24 in the PIC 30 has four optical modulators (Mod) 31a-31d arranged in parallel. CW light output from the LD 23 is input to the CW light input port of the optical transmitter 24. The CW light input port is equipped with a spot size converter (SSC) 33 to reduce coupling loss with the FA. In the optical transmitter 24, the CW light is branched into four paths and supplied to the four Mods 21a-21d. The CW light is modulated by a drive electrical signal supplied from a drive circuit 22 and output as a transmission optical signal. The output port of the transmission optical signal is also equipped with an SSC 34 to reduce coupling loss with the FA.

[0006] On the other hand, four photodetectors (PDs) 32a-32d are arranged in parallel in the optical receiver 16. The received optical signal from the SMF is photoelectrically converted by the PD 32 (hereinafter, the sub-numbers of the reference numerals in the drawings will be omitted as appropriate). The input port of the received optical signal is also equipped with an SSC 33 to reduce the coupling loss with the FA.

[0007] As shown in FIG. 2, the SMF is connected via the connector 25, so that the input of the CW light from the LD 13 and the input and output of the optical signal are performed via one side of the chip substrate of the PIC 30.

[0008] Because the optical engine module 10 is mounted on the PCB 15 via a socket, it has a constriction in a direction perpendicular to the optical axis direction of the optical fiber 14, as shown in FIG. 1 . Therefore, in order to pull out the optical fiber 14 from the optical engine module 10, it is necessary to avoid this constriction. Therefore, in the case of the optical engine module 10 equipped with two optical devices 12 as shown in FIG. 1 , two types of optical devices with different FA connection positions are mounted so that the FA connection position of one optical device is positioned close to the other optical device. Therefore, two types of optical devices with different arrangements of the PIC 30 and connector 25 have to be designed and manufactured, which poses a problem of increased costs.

[0009] Chongjin Xie, et al, “Real-Time Demonstration of Silicon-Photonics-Based QSFP-DD 400GBASE-DR4 Transceivers for Datacenter Applications,” T3H.5, OFC2020.

[0010] One embodiment of the present invention is an optical device in which an optical transmitter including a plurality of optical modulators and an optical receiver including a plurality of photodetectors are integrated on a chip substrate, and the input and output of optical signals to the optical transmitter and the input of optical signals to the optical receiver are concentrated on one side of the chip substrate and on the side opposite to the one side.

[0011] A plurality of spot size converters for inputting and outputting the optical signal and for inputting the optical signal can be provided in contact with the one side and the side opposite to the one side.

[0012] FIG. 1 is a block diagram showing the configuration of a conventional optical engine module, FIG. 2 is a diagram showing the configuration of a conventional optical transceiver, FIG. 3 is a diagram showing the configuration of a PIC in a conventional optical transceiver, FIG. 4 is a diagram showing the configuration of a PIC in an optical transceiver according to a first embodiment, FIG. 5 is a diagram showing the configuration of a PIC in an optical transceiver according to a second embodiment, and FIG. 6 is a diagram showing the configuration of an optical modulator in an optical transceiver.

[0013] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, an optical transceiver that transmits and receives optical signals using four parallel SMFs will be described as an example, but there is no limit to the number of parallel SMFs, and this embodiment can be applied regardless of the modulation method.

[0014] 4 shows the configuration of a PIC in an optical transceiver according to Example 1. This is an example of an optical transceiver 20 that transmits and receives optical signals using four parallel SMFs. In the PIC 40, an optical transmitter TX, which is an optical device in the optical system, has four optical modulators (Mod) 41 arranged in parallel, and an optical receiver RX has four photodetectors (PD) 42 arranged in parallel.

[0015] An optical waveguide is formed between the SSC 43R and the Modulator 41 so that the input of CW light from the LD 23 and the output of the transmission optical signal from the optical transmitter TX are performed via one side (right side) of the chip substrate of the PIC 40. In addition, an optical waveguide is formed between the SSC 43L and the Modulator 41 so that the input and output of the optical signal can also be performed from the opposing side (left side) of the chip substrate of the PIC 40. For example, if the Modulator 41 is a Mach-Zehnder interferometer (MZI) type modulator that utilizes the electro-optic effect, bidirectional operation is possible simply by changing the propagation direction of the optical signal and the electrical signal for modulation. Details will be described later with reference to FIG. 6.

[0016] Similarly, an optical waveguide is formed between the optical receiver RX and the PD 42 via the SSC 43R so that a received optical signal can be input to the optical receiver RX via one side (right side) of the chip substrate. In addition, an optical waveguide is formed between the optical receiver RX and the PD 42 via the SSC 43L so that an optical signal can also be input from the opposing side (left side) of the chip substrate.

[0017] When optical signals are input or output via one side of the chip substrate, nothing is connected to the input or output on the opposing side of the chip substrate. In this way, the input and output terminals of the optical signals to the optical transmitter TX and the input terminals of the optical signals to the optical receiver RX are concentrated on one side of the chip substrate, and also on the side opposite to that side, so that optical signals can be input or output on either the left or right side of the chip substrate of the PIC 40.

[0018] Furthermore, the optical transmitter TX and optical receiver RX are disposed above the chip substrate of the PIC 40, as shown in Fig. 4. When inputting and outputting optical signals via one side (the right side) of the chip substrate in the state shown in Fig. 4, i.e., when inputting and outputting optical signals via SSC 43R, the connector consisting of the FA is connected above the chip substrate. On the other hand, when the chip substrate of the PIC 40 is turned upside down from the state shown in Fig. 4 and inputting and outputting optical signals via the right side of the chip substrate, i.e., when inputting and outputting optical signals via SSC 43L, the connector consisting of the FA is connected below the chip substrate.

[0019] Therefore, two types of optical devices with different arrangements of PICs and connectors can be realized with a single optical device, thereby suppressing cost increases.

[0020] 5 shows the configuration of a PIC in an optical transceiver according to Example 2. This is an example of an optical transceiver 20 that transmits and receives optical signals using four parallel SMFs. In the PIC 50, an optical transmitter TX, which is an optical device in the optical system, has four optical modulators (Mod) 51 arranged in parallel, and an optical receiver RX has four photodetectors (PD) 52 arranged in parallel.

[0021] An optical waveguide is formed between SSC 53R and Mod 51 so that the input of CW light from LD 23 and the output of a transmission optical signal from the optical transmitter TX are performed via one side (right side) of the chip substrate of PIC 50. In addition, an optical waveguide is formed between SSC 53L and Mod 51 so that an optical signal can be input / output from the opposing side (left side) of the chip substrate of PIC 50.

[0022] The difference from the first embodiment is that optical waveguides branching into four paths from the SSC that inputs the CW light to the four Mod 51 are formed outside the SSC, that is, between the SSC and one side that is the end face of the chip substrate. Compared to the configuration of the first embodiment, there is no intersection of the optical waveguides, which makes it possible to reduce the loss of the optical signal.

[0023] An optical waveguide is formed between the optical receiver RX and the PD 52 via the SSC 53R so that a received optical signal can be input to the optical receiver RX via one side (right side) of the chip substrate. In addition, an optical waveguide is formed between the optical receiver RX and the PD 52 via the SSC 53L so that an optical signal can also be input from the opposing side (left side) of the chip substrate.

[0024] With this configuration, when inputting and outputting optical signals via one side (right side) of the chip substrate, dicing is performed along dicing line 54R and a portion of the right side of the chip substrate is removed. As a result, the input / output terminals of SSC 53R provided on the right side are exposed at the diced end surface, allowing input and output of optical signals. Similarly, when inputting and outputting optical signals via the opposing side (left side) of the chip substrate, dicing is performed along dicing line 54L and a portion of the left side of the chip substrate is removed, allowing the input / output terminals of SSC 53L provided on the left side to be exposed at the diced end surface, allowing input and output of optical signals.

[0025] Therefore, similar to the first embodiment, optical signals can be input and output on either the left or right side of the chip substrate of the PIC 50. Furthermore, if the optical transmitter TX and optical receiver RX are disposed above the chip substrate of the PIC 40 as shown in Fig. 5, the connection of the connector made of the FA can be made either above or below the chip substrate.

[0026] Note that the dicing lines 55 may be formed in advance as grooves on the chip substrate so that they can be visually observed. However, although the dicing lines are shown as thick solid lines in Fig. 5, they should be dashed lines that do not intersect with the optical waveguides so as not to cut the optical waveguides.

[0027] 6 shows the configuration of an optical modulator in an optical transceiver. It is an enlarged view of a portion Mod 51a of a PIC 50 in the optical transceiver of Example 2. The optical modulator (Mod) 61 is an MZI-type modulator, and is configured by connecting two 2x2 couplers 71 and 72, each consisting of a directional coupler, with two modulation waveguides 73a and 73b between them.

[0028] For example, when optical signals are input and output via the right side of the chip substrate, CW light from LD 23 is input via SSC64R-CW. In Mod 61, CW light input from Port 1 of 2x2 coupler 71 is branched and output from Ports 3 and 4, and undergoes phase modulation according to the drive electrical signal as it propagates through modulation waveguides 73a and 73b. The two phase-modulated optical signals are input to Ports 3 and 4 of 2x2 coupler 72, where they interfere to become the desired modulated signal. The modulated transmission optical signal is output via SSC64R-Out.

[0029] Similarly, when optical signals are input and output via the left side of the chip substrate, CW light from LD 23 is input via SSC64L-CW. In Mod 61, CW light input from Port 1 of 2x2 coupler 72 is branched and output from Ports 3 and 4, and undergoes phase modulation according to the driving electrical signal by propagating through modulation waveguides 73a and 73b. The two phase-modulated optical signals are input to Ports 3 and 4 of 2x2 coupler 71 and interfere to become the desired modulated signal. The modulated transmission optical signal is output via SSC64L-Out.

[0030] By using an MZI type modulator for Mod 61, bidirectional operation is possible, allowing optical signals to be input and output on either the left or right side of the chip substrate of PIC 50. Although a directional coupler is shown as an example of a 2x2 coupler, a multimode interference (MMI) type 2x2 coupler can also be used. The termination resistor that terminates the driving electrical signal is not mounted on the PIC 50, but is instead located on a separate substrate.

[0031] According to this embodiment, in an optical device (PIC) including an optical transmitter and an optical receiver of an optical system, optical signals can be input and output using either one of the opposing sides of the chip substrate or the side opposite to that side during packaging. In addition, by flipping the optical device 180 degrees during packaging, the FA can be connected to a different position. In this way, optical devices with various connection configurations can be realized with a single type of optical device, which reduces the cost increase of the optical device.

[0032] Although an example in which SSC is inserted into the input / output of the optical transmitter and the input of the optical receiver has been described, this embodiment can also be applied to cases in which SSC is not inserted.

[0033] 10 Optical engine module 11 Optical communication electronic device (PHY) 12 Optical device 13 Fiber array (FA) 14 Optical fiber 15 Printed circuit board (PCB) 20 Optical transceiver 21 DSP chip 22 Driver circuit 23 Laser diode (LD) 24 Optical transmitter (TX) 25 Connector 26 Optical receiver (RX) 27 Amplifier (TIA) 30, 40, 50 Optical integrated circuit (PIC) 31, 41, 51 Optical modulator (Mod) 32, 42, 52 Photodetector (PD) 43, 53 Spot size converter (SSC) 54 Dicing line

Claims

1. An optical device in which an optical transmitter including multiple optical modulators and an optical receiver including multiple photodetectors are integrated on a chip substrate, wherein the input / output terminal for optical signals to the optical transmitter and the input terminal for optical signals to the optical receiver are concentrated on one side of the chip substrate and on the side opposite to the one side.

2. An optical device according to claim 1, characterized in that a spot size converter is inserted at each of the input / output end of the optical signal and the input end of the optical signal, in contact with the one side and the side opposite to the one side.

3. The optical device according to claim 2, further comprising dicing lines parallel to the one side and the side opposite the one side, and by performing dicing along the dicing lines, the input / output ends of the plurality of spot size converters are exposed on the diced end surface.

4. The optical device according to claim 1, 2 or 3, characterized in that the optical modulator is a Mach-Zehnder interferometer modulator including a first 2x2 coupler, a second 2x2 coupler, and two modulation waveguides connecting the first 2x2 coupler and the second 2x2 coupler.

5. The optical device of claim 4, wherein the first 2x2 coupler and the second 2x2 coupler are directional couplers or multimode interference (MMI) type couplers.

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