CN114039668A - Modulator chip assembly for high rate optical signal generation - Google Patents

Abstract

The invention discloses a modulator chip assembly for generating high-speed optical signals, which comprises a modulator chip, at least one high-speed signal transmission line, at least one ground wire, a capacitor, a resistor and at least two sections of gold wires, wherein the modulator chip is connected with the ground wire; wherein the length of the first gold thread is L1, and L1 is more than 0.05 mm and less than or equal to 1 mm; or the length L1 of the first gold wire is less than or equal to 0.05 mm; the first inductor is connected with the first gold wire at one end, and is connected with the capacitor at the other end through the high-speed signal transmission line; the first inductor is positioned between the modulator chip and the capacitor; the first inductor is connected in series with the modulator chip. The invention further improves the bandwidth of the modulator chip by adding a parallel capacitor and a series inductor between the microwave signal line and the modulator chip, thereby enabling the low-bandwidth modulator to be applied to the modulation of signals of 50G and above, and realizing the low cost and conveniently increasing the bandwidth of the modulator chip assembly.

Description

Modulator chip assembly for high rate optical signal generation

Technical Field

The invention relates to a signal modulation device in the field of communication, in particular to a modulator chip assembly for generating a high-speed optical signal.

Background

With the construction of large-scale data centers, 100G/400G/800G transmission technology has become a necessity. However, there are many challenges in upgrading from a conventional 10G network to a network of 100G/400G/800G or more, one of which is the need for a high bandwidth, low cost modulator chip for high speed optical signals.

At present, the core modulation chip for realizing single-wave 100G and four-channel 400G transmission is a semiconductor electro-absorption modulation laser with 50 Gb/s. Semiconductor electroabsorption modulators, which are key chips for high-speed optical signal generation, have bandwidth limited mainly by junction capacitance and parasitic capacitance of the chip. Therefore, to increase the modulation bandwidth of the electro-absorption modulator, the most direct method is to reduce the length of the electro-absorption modulator to reduce the junction capacitance of the detector chip, and simultaneously reduce the area of the electrode, increase the thickness of the dielectric material and utilize special low-k material to reduce the parasitic capacitance, thereby increasing the 3dB bandwidth of the modulation chip. However, reducing the length of the electro-absorption chip will reduce the extinction ratio of the modulator and increase the required operating voltage of the electro-absorption modulator; the area of the electrode is limited by the requirement of routing, the diameter is generally difficult to be less than 50 micrometers, the process difficulty of low dielectric constant materials (such as BCB and benzocyclobutene) is greatly increased, and the cost is also increased. Therefore, there is a great limitation in reducing the junction capacitance and parasitic capacitance of the chip. At present, the junction capacitance of a common electro-absorption modulator is about 0.1pF, the parasitic capacitance is about 0.2pF, the RC bandwidth is less than 30GHz, and the modulation requirement of 50Gbit/s signals cannot be met. If an electro-absorption modulator with high junction capacitance and parasitic capacitance can be used, it would be of great practical significance to increase the modulation bandwidth of the modulator through peripheral circuits.

A package structure of a conventional electroabsorption modulated laser is shown in fig. 1, and includes an electroabsorption modulated laser 1 and a ceramic substrate 2, where the electroabsorption modulated laser 1 includes an electroabsorption modulator 1a and a semiconductor laser 1b, and an electrical signal is applied to the electroabsorption modulator 1a to modulate a direct current generated by the semiconductor laser to generate a high-speed optical signal for output. The ceramic substrate 2 includes a plurality of microwave transmission lines and electrodes (3a, 3b, 3c are signal transmission lines for connecting the electro-absorption modulator 1a and transmission lines 13a, 13b, 13c for transmitting an electric signal of an external circuit, where 3b and 13b are high-speed signal lines and 3a, 3c and 13a, 13c are ground lines) for connecting an external circuit and the electro-absorption modulated laser 1, and a resistor 6 (typically 50 ohms) for impedance matching with an external rf driver. The transmission lines 3a, 3b, 3c and the transmission lines 13a, 13b, 13c are connected by gold wires 12a, 12b, 12 c. The signal line 3b is connected to the electro-absorption modulator 1a via a first gold wire 9. The current for driving the dc semiconductor laser 1b is applied to the semiconductor laser 1b through the electrode 15 of the external package circuit, the electrode 4 on the ceramic substrate 2, and the gold wire 10. The first terminal electrode 7 of the matching resistor 6 is connected to an external ground electrode 14 via a gold wire 11, and the second terminal electrode 5 of the matching resistor 6 is connected to the electrode of the electro-absorption modulator 1a via a second gold wire 8. In fig. 1, a decoupling capacitor which may be required for an external driving current of the semiconductor laser 1b is not shown, and a specific wiring position may be adjusted. In general, in order to reduce the parasitic effect introduced by the package as much as possible, the first gold wire 9 and the second gold wire 8 connecting the electro-absorption modulator 1a with the signal line 3b and the matching resistor 6 need to be as short as possible to reduce the self-induced inductance generated by the gold wires themselves.

Fig. 2 shows a small signal S21 curve obtained from a simulation of an electro-absorption modulator chip with a junction capacitance of 0.1pF and a parasitic capacitance of 0.2pF, calculated based on the equivalent circuit of the modulator chip and a 50 ohm load resistance. FIG. 2 shows that the 3dB bandwidth is 22.4GHz, which can meet the modulation requirement of 25Gb/s signal, but there is a small distance from the bandwidth above 35GHz required by the modulation of 50Gb/s signal. Increasing the bandwidth by greatly reducing the junction capacitance and parasitic capacitance presents significant challenges to both chip performance and process.

It has been found that adding a suitable inductance between the electro-absorption modulator 1a and the matching resistor 6, while minimizing the package-induced parasitic effects, will increase the modulation bandwidth of the electro-absorption modulator to some extent. Based on this idea, a package structure of the electro-absorption modulated laser as shown in fig. 3 can be adopted, which adds an inductor 16 between the electro-absorption modulator 1a and the matching resistor 6 to increase the modulation bandwidth of the modulator chip. The electro-absorption modulator 1a is connected to an inductor 16 through a second gold wire 8, and the inductor 16 is connected to the second terminal electrode 5 of the matching resistor 6. If a separate inductor is used, the inductor 16 and the second terminal electrode 5 may be connected by another gold wire. Tests show that the bandwidth of a modulator chip can be increased by about 50% by adding one inductor. As shown in fig. 4, which is the theoretically calculated small signal bandwidth at different inductance values, when the inductance 16 is 0.25nH, the 3dB bandwidth is increased from 22.4GHz without inductance to 32 GHz; when the inductance 16 increases to 0.5nH, the 3dB bandwidth increases to 33 GHz; when the inductance 16 is 0.75nH, the 3dB bandwidth is 32.4 GHz; continuing to increase the inductance, the bandwidth will begin to decrease. Although the bandwidth of the modulator can be increased from 22.4GHz to about 33GHz by introducing the inductor, the 3dB bandwidth of the modulator is required to be over 35GHz to modulate 50Gb/s signals, so that the mere addition of the inductor to the intrinsic bandwidth of the modulator, namely 22GHz, is not enough to ensure the modulation of the 50Gb/s signals.

Disclosure of Invention

The present invention is directed to a modulator chip assembly for high-speed optical signal generation, which can increase the modulation bandwidth of a semiconductor electro-absorption modulator, thereby enabling a low-bandwidth modulator chip to be applied to high-speed optical signal generation.

In order to solve the above technical problem, the technical solution of the present invention for a modulator chip assembly for high-rate optical signal generation is:

the high-speed signal transmission line comprises a modulator chip, at least one high-speed signal transmission line, at least one ground wire, a capacitor, a resistor and at least two sections of gold wires; the high-speed signal transmission line is used for realizing the connection with an external circuit; the capacitor is positioned between the high-speed signal transmission line and the ground wire; one end of the capacitor is connected with the high-speed signal transmission line, and the other end of the capacitor is grounded with the modulator chip; the capacitor is connected with the modulator chip in parallel; the resistor is positioned between the modulator chip and the grounding electrode, and the resistor is connected with the modulator chip in series and used for matching with the impedance of an external radio frequency driver; the first gold wire is connected with the modulator chip, the high-speed signal transmission line and the capacitor, and the second gold wire is connected with the modulator chip and the resistor; wherein the length of the first gold thread is L1, and L1 is more than 0.05 mm and less than or equal to 1 mm; or the length L1 of the first gold wire is less than or equal to 0.05 mm; the first inductor is connected with the first gold wire at one end, and the other end of the first inductor is connected with the capacitor through the high-speed signal transmission line; the first inductor is positioned between the modulator chip and the capacitor; the first inductor is connected in series with the modulator chip.

In another embodiment, the inductance value of the first inductor is between 0.01nH and 1 nH.

In another embodiment, the inductance value of the first inductor is between 0.05nH and 1 nH.

In another embodiment, the length of the second gold wire is L2, and is more than 0.1 mm and less than or equal to L2 and less than or equal to 1 mm.

In another embodiment, the length L2 of the second gold wire is less than or equal to 0.1 mm; the first inductor is connected with the first gold wire, and the other end of the first inductor is connected with the resistor; the second inductor is positioned between the modulator chip and the resistor; the second inductor is connected in series with the detector chip.

In another embodiment, the inductance value of the second inductor is between 0.05nH and 1 nH.

In another embodiment, the inductance value of the second inductor is between 0.1nH and 1 nH.

In another embodiment, the modulator chip is an electro-absorption modulated laser.

In another embodiment, the length of the first gold wire is L1, 0.05 mm < L1 ≤ 1 mm, and the self-induction inductance generated by the first gold wire is between 0.01nH and 1 nH; and/or the length of the second gold wire is L2, the L2 is more than 0.1 mm and less than or equal to 1 mm, and the self-induction inductance generated by the second gold wire is between 0.05nH and 1 nH.

In another embodiment, the capacitance value of the capacitor is between 0.01pF and 0.6 pF.

The invention can achieve the technical effects that:

the invention further improves the bandwidth of the modulator chip by adding a parallel capacitor and a series inductor between the microwave signal line and the modulator chip, thereby enabling the low-bandwidth modulator to be applied to the modulation of signals of 50G and above, and realizing the low cost and conveniently increasing the bandwidth of the modulator chip assembly.

The modulator chip of the invention converts the external high-speed electrical signal into a high-speed optical signal, and the high-speed electrical signal is input into the modulator chip through the capacitance inductor, thereby generating the required high-speed modulated optical signal. By selecting proper inductance and capacitance, the invention can greatly increase the modulation bandwidth of the modulator chip, thereby realizing the generation of high-speed optical signals by using the low-cost and low-bandwidth modulator chip.

The invention utilizes a low-cost peripheral circuit and a low-bandwidth modulator chip to realize the promotion of the modulator bandwidth and the generation of high-speed optical signals without developing a high-bandwidth modulator chip with great technical difficulty, thereby solving the limitation of chip shortage of the high-bandwidth modulator in the current market.

The invention can be compatible with the existing modulator chip packaging technology, does not need to additionally develop a new packaging process and increase the chip packaging size, and can be suitable for all optical devices and optical modules. Therefore, the technical scheme of the invention can ensure large-scale production and simultaneously has lower cost compared with a high-bandwidth modulator chip.

The invention can overcome the bandwidth limitation of the prior semiconductor modulator chip applied to the generation of high-speed optical signals of 50G or above, and the modulator chip with low bandwidth is used for the generation of high-speed optical signals of 50G or above, thereby utilizing the prior mature modulator chip with low cost and high reliability and the assembly manufacturing process to realize the generation of high-speed optical signals of 50G or above.

Drawings

It is to be understood by those skilled in the art that the following description is only exemplary of the principles of the present invention, which may be applied in numerous ways to achieve many different alternative embodiments. These descriptions are made for the purpose of illustrating the general principles of the present teachings and are not meant to limit the inventive concepts disclosed herein.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general description given above and the detailed description of the drawings given below, serve to explain the principles of the invention.

The invention will be further described in detail with reference to the drawings and specific examples, so as to clearly understand the structure and the working principle of the invention, but the protection scope of the invention is not limited thereby.

FIG. 1 is a schematic diagram of a prior art modulator chip assembly;

FIG. 2 is a plot of the intrinsic small signal response curve S21 for the chip shown in FIG. 1, with frequency (in GHz) on the abscissa and small signal response S21 (in dB) on the ordinate;

FIG. 3 is a schematic diagram of a prior art modulator chip assembly with an inductor;

FIG. 4 is a graph of a simulated small signal response curve S21 of the chip of FIG. 3 with different inductors added;

FIG. 5 is a schematic diagram of the structure of embodiment 1 of the modulator chip assembly of the present invention for high rate optical signal generation;

FIG. 6 is a graph of the signal response curve S21 of example 1 of the present invention with a different first inductor added to the capacitor and a second inductance of 0.5 nH;

FIG. 7 is a graph of the signal response curve S21 of example 1 of the present invention with different capacitors added when there is no first inductor and the second inductance value is 0.5 nH;

FIG. 8 is a graph of the signal response curve S21 of embodiment 1 of the present invention with the addition of a different first inductor at a capacitance of 0.1pF and a second inductance of 0.5 nH;

FIG. 9 is a graph of the signal response curve S21 of embodiment 1 of the present invention with the addition of a different second inductor at a capacitance of 0.1pF and a first inductance of 0.1 nH;

FIG. 10 is a graph of the signal response curve S21 of example 1 of the present invention with different capacitors added at the first inductance value of 0.1nH and the second inductance value of 0.5 nH;

FIG. 11 is a graph of the signal response curve S21 for a different modulator chip of embodiment 1 of the present invention without the capacitor, the first inductor, and the second inductor, and with the capacitor, the first inductor, and the second inductor added;

fig. 12 is a schematic structural diagram of embodiment 2 of the modulator chip assembly for high-rate optical signal generation according to the present invention, which replaces the second inductor with a second gold wire;

fig. 13 is a schematic structural diagram of a modulator chip assembly of embodiment 3 for high-rate optical signal generation according to the present invention, in which a first gold wire is used instead of a first inductor, and a second gold wire is used instead of a second inductor.

The reference numbers in the figures illustrate:

1 is an electro-absorption modulated laser, 2 is a ceramic substrate,

1a an electro-absorption modulator, 1b a semiconductor laser,

3a, 3b, 3c are signal transmission lines, 4 are electrodes,

5 is a second terminal electrode of the resistor, 6 is a matching resistor,

7 is a first terminal electrode of a resistor, 8 is a second gold wire,

9 is a first gold wire, 9 is,

10 is a gold wire connecting an electrode of an external package circuit and a semiconductor laser,

11 is a gold wire connecting the matching resistor and the grounding electrode,

12a, 12b and 12c are gold wires connecting the high-speed signal lines with external circuits,

13a, 13b, 13c are signal transmission lines for transmitting external circuits,

reference numeral 14 denotes an external ground electrode,

15 is an electrode of an external package circuit for supplying power to the semiconductor laser,

reference numeral 16 is a second inductance which is,

the reference numeral 17 is a capacitance, and,

reference numeral 18 denotes a first inductor.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention. Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. As used herein, the terms "first," "second," and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" and similar words are intended to mean that the elements or items listed before the word cover the elements or items listed after the word and their equivalents, without excluding other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

The core idea of the invention is to realize the generation of high-speed optical signals higher than the intrinsic bandwidth of the modulator chip by combining an additional circuit based on inductance and capacitance with the modulator chip to increase the bandwidth of the modulator chip component. The semiconductor modulator chip converts a high-speed electrical signal (generally, a reverse bias voltage) into a high-speed optical signal by changing the absorption intensity of passing dc light by an applied high-speed electrical signal.

Although the bandwidth of a chip can be theoretically increased by reducing the junction capacitance and parasitic capacitance of the chip to meet the bandwidth requirement of 50G or even 100G, the junction capacitance and parasitic capacitance are closely related to the size of the chip and the process used, and the reduction of the capacitance generally requires the reduction of the size of the chip and the use of special dielectric materials. However, due to the limitation of semiconductor materials and chip processes, the physical size cannot be infinitely reduced, and the more serious problem is that the reduction of the chip length will limit the intensity of light that can be absorbed by the modulator, greatly reduce the extinction ratio of high-speed optical signals, and is not favorable for the transmission and detection of the high-speed optical signals. In addition, special dielectric materials are introduced in the chip manufacturing process, so that the chip manufacturing process is complicated, the cost of the chip is increased, and the interest rate of the chip is reduced. All of this will increase the packaging and manufacturing costs of the high bandwidth modulator chip.

The invention can properly adjust the overall performance of the circuit through the additional inductor and the capacitor, thereby increasing the modulation bandwidth of the modulator chip assembly. The following will describe in detail how the present invention can achieve high-rate 50Gbps optical signal generation using a low-bandwidth modulator chip, taking a 50G modulator chip assembly as an example. Obviously, the technical scheme of the invention is also suitable for the bandwidth increase of the modulator chip with the high speed of 50G or more.

Based on the idea of the invention, the modulator chip and a compensation circuit composed of a capacitor and an inductor form a modulator chip assembly, and the high-speed electrical signal is not directly applied to the modulator chip, but is applied to the modulator chip through the compensation circuit, so that the generation of the high-speed optical signal is realized.

The invention relates to a modulator chip assembly for generating high-speed optical signals, which mainly comprises a modulator chip (such as a semiconductor electric absorption modulation laser), a capacitor, an inductor, a resistor, a TIA (transimpedance amplifier), a gold wire for connecting elements and a lead wire for connecting an external circuit, wherein the lead wire is used for inputting high-speed electric signals; the capacitor is positioned between the external high-speed signal line and the inductor and is connected with the inductor and the modulator in parallel; an inductor is positioned between the capacitor and the modulator and is connected in series with the modulator chip.

The modulator chip assembly of the present invention applies an input high-speed electrical signal to the modulator chip after passing through a circuit comprising an inductor and a capacitor. The modulator chip can modulate the frequency response of the whole circuit by selecting proper inductance and capacitance values, thereby improving the bandwidth of the whole modulator chip assembly.

To achieve the above-mentioned objective of achieving high-speed optical signal generation based on a low-bandwidth modulator chip, the present invention is described by the following embodiments.

Example 1

As shown in fig. 5, the modulator chip assembly for high-speed optical signal generation according to the present invention includes an electro-absorption modulated laser 1, a capacitor 17, a second inductor 16, a first inductor 18, and a matching resistor 6; the electroabsorption modulation laser 1 comprises an electroabsorption modulator 1a and a semiconductor laser 1b, and a high-speed electrical signal is applied to the electroabsorption modulator 1a to modulate direct current emitted by the semiconductor laser 1b to generate a high-speed optical signal for output; all these components (including the electro-absorption modulated laser 1, the capacitor 17, the second inductor 16, the first inductor 18 and the matching resistor 6) are located on the same substrate 2;

the substrate 2 also contains a plurality of microwave transmission lines and electrodes for connecting external circuitry to the electro-absorption modulated laser and a resistor 6 (typically 50 ohms) for impedance matching with an external rf driver; 3a, 3b, 3c are transmission lines for connecting the electro-absorption modulator 1a with transmission lines 13a, 13b, 13c for transmitting external high-speed electric signals, where 3b and 13b are high-speed signal lines, 3a, 3c and 13a, 13c are ground lines; the transmission lines 3a, 3b, 3c are connected with the transmission lines 13a, 13b, 13c through gold wires 12a, 12b and 12 c;

the other end of the high-speed signal line 3b is connected with one end of a first inductor 18, and the other end of the first inductor 18 is connected with the electroabsorption modulator 1a through a first gold wire 9; the capacitor 17 is located between the high-speed signal line 3b and the first inductor 18; one end of the capacitor 17 is connected to the high-speed signal line 3b, and the other end is connected to the ground line 3 c; one end of the second inductor 16 is connected with the second end electrode 5 of the matching resistor 6, and the other end is connected with the electroabsorption modulator 1a through a second gold wire 8; the current for driving the direct current semiconductor laser 1b is applied to the semiconductor laser 1b through the electrode 15 of the external packaging circuit, the electrode 4 on the ceramic substrate 2 and the gold wire 10; the first terminal electrode 7 of the matching resistor 6 is connected to an external ground electrode 14 via a gold wire 11.

As a preferred embodiment, the capacitor 17, the first inductor 18, the second inductor 16, the matching resistor 6 and the electrical signal transmission lines 3a, 3b, 3c may be fabricated by a thin film process and integrated on the substrate 2, so as to facilitate packaging and save cost;

preferably, the electro-absorption modulated laser 1, the capacitor 17, the second inductor 16, the first inductor 18, the matching resistor 6 and the substrate 2 are packaged in a TO-CAN (package component).

On the basis of a large number of tests, the invention overcomes the technical prejudice that the first gold wire 9 and the second gold wire 8 need to be as short as possible to reduce the self-induction inductance generated by the gold wires, and the modulation bandwidth of the modulator can be improved by only adopting a proper inductance value to increase the inductance. Clearly, the values of capacitance and inductance directly determine the performance of the modulator chip package assembly.

The capacitor 17 may be a plate-type capacitor, and its capacitance value is controlled by the area and/or the thickness of the dielectric layer.

The inductance values of the first inductor 18 and the second inductor 16 are controlled by the size of the film;

the specific values of the capacitor 17, the first inductor 18 and the second inductor 16 may be optimized based on the performance of the modulator chip 1a and the signal rate to be achieved; preferably, the value of the capacitor 17 is between 0.01pF and 0.6 pF; the value of the first inductance 18 is between 0.01nH and 1 nH; the value of the second inductance 16 is between 0.05nH and 1 nH. Within this range the object of the invention of increasing the bandwidth can be achieved.

Further, the value of the first inductance 18 is between 0.05nH and 1 nH; the value of the second inductance 16 is between 0.1nH and 1 nH. Within this range, the performance of the modulator chip assembly is optimal.

Preferably, the substrate 2 is a ceramic substrate, although other suitable materials such as aluminum nitride, alumina, quartz or silicon based substrates may be used.

The following is an example of how the present invention uses a low bandwidth modulator chip for 50Gbps optical signal generation using a capacitor 17, a first inductor 18 and a second inductor 16. The junction capacitance of the modulator chip is 0.1pF, the parasitic capacitance is 0.2pF, and the corresponding intrinsic bandwidth is 22.4 GHz; when a second inductor 16 with an inductance value of 0.5nH is added, the modulation bandwidth is increased to 33GHz, but the modulation bandwidth requirement for generating 50Gbps optical signals cannot be completely met; by choosing the proper inductance and capacitance, the 3dB bandwidth of the modulator chip assembly will be able to be further improved when the capacitance 17 and the first inductance 18 in embodiment 1 are added.

Fig. 6 shows the corresponding small signal bandwidth when the second inductor 16 is 0.5nH, the capacitor 17 is not added, and the first inductor 18 is 0, 0.25nH and 0.5nH, respectively; in fig. 6, it is shown that when the second inductance 16 is 0.5nH, the 3dB bandwidth is reduced from 33GHz to 31.4GHz (0.25nH for the first inductance 18) and 25.2GHz (0.5 nH for the first inductance 18) by adding only the first inductance 18. Obviously, the shorter the gold wire from the high-speed signal line 3b to the modulator chip 1a, the better. Fig. 7 shows the corresponding 3dB bandwidths of 33GHz, 29.6GHz and 26GHz, respectively, when the second inductance 16 is 0.5nH, the first inductance 18 is not added, and the capacitance 17 is 0, 0.05pF and 0.1pF, respectively. Thus, adding only the capacitor 17 will significantly reduce the bandwidth of the modulator components, which is why conventional packaging needs to reduce the added capacitance as much as possible. However, through a great deal of experimental research, the present invention finds that the 3dB bandwidth of the signal is significantly increased after the capacitor 17 and the first inductor 18 are added simultaneously.

Fig. 8 shows the small signal response curves corresponding to the second inductor 16 of 0.5nH, the capacitor 17 of 0.1pF, and the first inductor 18 of 0, 0.1, 0.2, and 0.3nH, respectively, and the bandwidths of the small signal response curves are 33, 58.4, 42.4, and 35.2GHz, respectively. In fig. 8 it is shown that the bandwidth will be improved when a capacitor and another inductor are added simultaneously. When the capacitance value is 0.1pF, the modulation bandwidth can be increased from 33GHz to more than 58GHz, which is far beyond the modulation requirement of 50Gbps signals. Therefore, the addition of the capacitor 17 and the first inductor 18 will increase the high frequency response, greatly improving the bandwidth of the modulator chip assembly. When the first inductance 18 is increased from 0.1nH to 0.2nH or 0.3nH, the frequency response is reduced but still much higher than the original intrinsic bandwidth of the modulator chip, 22 GHz. Although the bandwidth of the first inductor 18 is reduced compared with the bandwidth of 0.1nH, the frequency response flatness is significantly improved, which is also important for the quality of the high-speed modulation signal, so that the bandwidth can be simultaneously increased and the frequency response flatness can be improved by adjusting the value of the first inductor 18. When the capacitor 17 and the first inductor 18 are added, the influence of the value of the second inductor 16 on the bandwidth is significantly reduced, but the flatness of the bandwidth can be improved to some extent by adjusting the value of the second inductor 16. Fig. 9 is a response curve for different second inductance values (0.25nH, 0.5nH, and 0.75nH) when the capacitance 17 is 0.1pF and the first inductance 18 is 0.1 nH. It can be seen that the 3dB bandwidth varies by less than 1GHz but has a greater effect on the flatness of the response curve. FIG. 10 is a graph showing the response of different capacitance values (0.1pF, 0.15pF and 0.2pF) when the first inductance value is 0.1nH and the second inductance value is 0.5 nH. With the increase of the capacitance value, the bandwidth is reduced to a certain extent, but still more than 50GHz, which is enough to meet the modulation requirement of 50Gb/s signals. Therefore, the combination of the capacitor 17, the second inductor 16 and the first inductor 18 can not only greatly improve the 3dB bandwidth of the modulator chip assembly, but also adjust the flatness of the signal response and improve the quality of the generated high-speed optical signal. The technique can be applied to the modulation of 100Gb/s high-speed optical signals. Fig. 11 is a signal response curve for a modulator with an intrinsic bandwidth of 32.6GHz (corresponding to a junction capacitance of 0.1pF, a parasitic capacitance of 0.1pF) before and after adding a capacitance 17 of 0.1pF, a first inductance 18 of 0.08nH and a second inductance 16 of 0.25 nH. It can be seen that the 3dB bandwidth is increased from 32.6GHz to 76.2GHz, and the bandwidth requirement of the 100Gb/s high-speed optical modulator can be met.

In embodiment 1, the second inductor 16 and the first inductor 18 are made by a thin film process and are located on the same substrate 2 as the capacitor 17; the modulator chip 1a is connected to the second inductor 16 and the first inductor 18 by the first gold wire 9 and the second gold wire 8, respectively. Since the gold wire used for chip connection has a diameter of about 25 μm, which itself generates a self-induced inductance, the second inductor 16 and the first inductor 18 in embodiment 1 may be replaced by gold wires, forming embodiments 2 and 3 of the present invention.

Example 2

As shown in fig. 12, the first inductor 18 originally located on the same substrate 2 as the capacitor 17 is replaced by a first gold wire 91 with a certain length; the first gold wire 91 not only provides connection of the signal line 3b to the modulator chip 1a, but also functions as the first inductor 18. Compared with embodiment 1, embodiment 2 replaces the first inductor 18 with gold wires, which not only reduces the cost, but also changes the inductance value because the length of the gold wires can be adjusted during chip packaging, so the gold wires with different lengths can play the role of adjustable inductors. Since the parameters of the modulator chips of different suppliers are different, adjusting the inductance value by changing the length of the first gold wire 91 will greatly facilitate adjusting the resonance characteristics for different modulator chips to obtain the optimum response performance. The size of the first gold wire 91 can be adjusted to obtain the best receiving bandwidth and response curve according to the performance of the modulator chip under the premise of considering the parasitic effect.

Example 3

Further, as shown in fig. 13, the first inductor 18, which is originally located on the same substrate 2 as the capacitor 17, is replaced by a first gold wire 92 having a certain length, and the second inductor 16 is replaced by a second gold wire 82. The first gold wire 92 not only provides connection of the signal line 3b to the modulator chip 1a but also functions as the first inductor 18, and the second gold wire 82 functions as the second inductor 16. Compared with embodiment 1, embodiment 3 uses two first gold wires 92 and second gold wires 82 with different lengths to replace the first inductor 18 and the second inductor 16, which not only can further reduce the cost, but also because the lengths of the gold wires can be adjusted during chip packaging, the inductance value changes accordingly, so the gold wires with different lengths can play the role of adjustable inductors. The dimensions of the first 92 and second 82 gold wires can be adjusted to optimize the receive bandwidth and response curve based on the performance of the modulator chip, taking into account parasitic effects.

In the above embodiment, the capacitor 17 is located between the signal line 3b and the ground line 3c, but may be located in the signal lines 3b and 3a, or other grounded electrodes or transmission lines. The ground lines 3a and 3c may have only one.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (10)

1. A modulator chip assembly for high rate optical signal generation, comprising:

a modulator chip;

at least one high-speed signal transmission line for realizing the connection with an external circuit and connecting an external high-speed electric signal with the modulator chip;

at least one ground wire;

the capacitor is positioned between the high-speed signal transmission line and the ground wire; one end of the capacitor is connected with the high-speed signal transmission line, and the other end of the capacitor is connected with the ground wire; the capacitor is connected with the modulator chip in parallel;

the resistor is positioned between the modulator chip and the grounding electrode, and is connected with the modulator chip in series and used for matching the impedance of an external radio frequency driver; and

the first gold wire is connected with the modulator chip, the high-speed signal transmission line and the capacitor, and the second gold wire is connected with the modulator chip and the resistor;

the length of the first gold wire is L1, and L1 is more than 0.05 mm and less than or equal to 1 mm; or the length L1 of the first gold wire is less than or equal to 0.05 mm; the first inductor is connected with the first gold wire at one end, and the other end of the first inductor is connected with the capacitor through the high-speed signal transmission line; the first inductor is positioned between the modulator chip and the capacitor; the first inductor is connected in series with the modulator chip.

2. The modulator chip assembly for high rate optical signal generation according to claim 1, wherein said first inductor has an inductance value between 0.01nH and 1 nH.

3. The modulator chip assembly for high rate optical signal generation according to claim 1, wherein said first inductor has an inductance value between 0.05nH and 1 nH.

4. The modulator chip assembly for high rate optical signal generation of claim 1 wherein the length of said second gold wire is L2, 0.1 mm < L2 ≦ 1 mm.

5. The modulator chip assembly for high-rate optical signal generation of claim 1, wherein the length L2 of said second gold wire is ≤ 0.1 mm; the first inductor is connected with the first gold wire, and the other end of the first inductor is connected with the resistor; the second inductor is positioned between the modulator chip and the resistor; the second inductor is connected in series with the detector chip.

6. The modulator chip assembly for high rate optical signal generation according to claim 5, wherein said second inductor has an inductance value between 0.05nH and 1 nH.

7. The modulator chip assembly for high rate optical signal generation according to claim 5, wherein said second inductor has an inductance value between 0.1nH and 1 nH.

8. The modulator chip assembly for high rate optical signal generation of claim 1, wherein said modulator chip is an electro-absorption modulated laser.

9. The modulator chip assembly of claim 1, wherein said first gold wire has a length of L1, 0.05 mm < L1 ≦ 1 mm, and wherein said first gold wire generates a self-induced inductance between 0.01nH and 1 nH; and/or the length of the second gold wire is L2, the L2 is more than 0.1 mm and less than or equal to 1 mm, and the self-induction inductance generated by the second gold wire is between 0.05nH and 1 nH.

10. The modulator chip assembly for high rate optical signal generation of claim 1, wherein said capacitor has a capacitance value between 0.01pF and 0.6 pF.

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