Laser bandwidth compensation integrated structure and laser transmitting module

Abstract

The embodiment of the invention provides a laser bandwidth compensation integrated structure, which comprises a microwave circuit, a laser chip and an optical coupling structure, and is characterized in that the microwave circuit comprises a high-frequency circuit and a direct-current bias circuit, and the high-frequency circuit is used for transmitting a radio-frequency signal from the outside of the laser bandwidth compensation integrated structure to the laser chip; the high-frequency circuit comprises a capacitance compensation structure which is arranged at the tail end of the high-frequency circuit; the direct current bias circuit is used for providing bias current for the laser chip; the laser chip is arranged corresponding to the microwave circuit and is used for loading an electric signal on an optical signal to realize direct modulation so as to output the optical signal; and the optical coupling structure is arranged corresponding to the laser chip and is used for outputting the optical signal. A capacitance compensation structure is arranged on a microwave circuit, a capacitive bonding pad branch knot is added, parasitic inductance generated by a laser and a microwave circuit bonding wire is compensated, and then the bandwidth of a laser chip is improved.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to an integrated structure for laser bandwidth compensation and a laser emitting module. Background Technology

[0002] With the rapid growth of broadband services, optical communication devices are developing towards integration, high capacity, small size, and high bandwidth. This trend towards high bandwidth has made high-speed laser modules a research hotspot. As a core component of fiber optic communication networks, the structure of the laser transmitting module directly determines its performance. In high-speed laser module packaging, gold wire bonding is typically used to connect the electrodes of the high-frequency circuit and the laser chip. As the operating frequency increases, the parasitic inductance effect of the bonding wire significantly affects the bandwidth of the directly modulated laser. Furthermore, traditional optical coupling structures typically use collimating lenses, isolators, and focusing lenses, thus requiring a large amount of space and having a complex structure, which is not conducive to adjusting the optical path. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address at least one of the aforementioned technical problems in existing laser bandwidth compensation integrated structures, embodiments of the present invention provide a laser bandwidth compensation integrated structure and a laser emitting module. By setting a capacitor compensation structure on the microwave circuit and increasing capacitive pad stubs, the parasitic inductance generated by the bonding lines between the laser and the microwave circuit is compensated, thereby improving the bandwidth of the laser chip.

[0005] (II) Technical Solution

[0006] To address the aforementioned technical problems, embodiments of the present invention propose an integrated structure for laser bandwidth compensation and a laser emitting module.

[0007] According to a first aspect of the present invention, a laser bandwidth compensation integrated structure is provided, comprising: a microwave circuit, a laser chip, and an optical coupling structure, wherein the microwave circuit includes a high-frequency circuit and a DC bias circuit, wherein the high-frequency circuit is used to transmit a radio frequency signal from outside the laser bandwidth compensation integrated structure to the laser chip; the high-frequency circuit includes a capacitor compensation structure disposed at the end of the high-frequency circuit, which improves the bandwidth of the laser chip by compensating for the parasitic inductance generated by the bonding wire between the laser chip and the microwave circuit; and the DC bias circuit is used to provide a bias current to the laser chip; the laser chip is correspondingly disposed with the microwave circuit, and is used to directly modulate an electrical signal onto an optical signal to output an optical signal, wherein the electrical signal includes a radio frequency signal; and the optical coupling structure is correspondingly disposed with the laser chip, and is used to transmit the optical signal to the outside of the laser bandwidth compensation integrated structure.

[0008] In some exemplary embodiments, the high-frequency circuit also includes a DC electrode for providing a DC signal to the laser chip.

[0009] In some exemplary embodiments, the integrated structure also includes a thermistor disposed on one side close to the laser chip for monitoring the operating temperature of the laser chip; and a semiconductor cooler for working in conjunction with the thermistor to achieve stable control of the operating temperature of the laser chip.

[0010] In some exemplary embodiments, the integrated structure further includes: a laser high-frequency housing disposed outside the laser chip and the microwave circuit, wherein the laser high-frequency housing includes: a light emission interface disposed on the laser high-frequency housing for allowing light signals to pass through and be transmitted to the outside of the laser high-frequency housing; a radio frequency interface disposed on the outer surface of the laser high-frequency housing for inputting external radio frequency signals into the high-frequency circuit; and a DC pin disposed on the outer surface of the laser high-frequency housing for providing bias current to the laser chip and current to the thermistor and the thermoelectric cooler.

[0011] In some exemplary embodiments, the structure of the high-frequency circuit includes one of a coplanar waveguide structure, a microstrip line structure, a stripline structure, or a differential transmission line structure.

[0012] In some exemplary embodiments, the microwave circuit further includes: a metal via disposed on the surface of the microwave circuit for eliminating resonance phenomena in the high-frequency circuit; and a side metallization structure disposed on the side of the high-frequency circuit for connecting the ground electrodes of the upper and lower surfaces of the high-frequency circuit.

[0013] In some exemplary embodiments, the radio frequency electrode of the laser chip is connected to the signal line of the high-frequency circuit; the DC electrode of the laser chip is connected to the DC electrode of the high-frequency circuit; and the N-pole of the laser chip is connected to the ground electrode of the microwave circuit.

[0014] In some exemplary embodiments, the high-frequency circuit includes a thin-film resistor connected in series in the high-frequency circuit to achieve impedance matching; and the DC bias circuit includes a high-frequency tapered inductor connected in series in the DC bias circuit to prevent high-frequency signal leakage.

[0015] In some exemplary embodiments, the optical coupling structure includes: a self-focusing lens disposed after the light-emitting surface of the laser chip, used to match the optical signal output by the laser chip with the numerical aperture of the optical fiber to reduce the power loss of the optical signal; an isolator disposed after the self-focusing lens, used to reduce the reflected light from the end faces of each component, preventing the reflected light from being injected back into the laser chip and causing nonlinear effects, so as to ensure the modulation characteristics and spectral characteristics of the laser; and an optical fiber assembly disposed corresponding to the optical emission interface, with the end face of the optical fiber assembly tilted at an octave angle to reduce the reflection of reflected light in the fiber core, thereby reducing return loss.

[0016] In some exemplary embodiments, the centers of the self-focusing lens, isolator, and fiber optic assembly are on the same horizontal line.

[0017] According to a second aspect of the present invention, a laser emitting module is provided, comprising the laser bandwidth compensation integrated structure of any of the above.

[0018] (III) Beneficial Effects

[0019] As can be seen from the above technical solutions, the laser bandwidth compensation integrated structure and laser emitting module provided by the embodiments of the present invention have at least the following beneficial effects:

[0020] (1) By adding capacitive pad stubs, i.e., capacitor compensation structures, to the microwave circuit, the parasitic inductance generated by the bonding line between the laser and the microwave circuit is compensated, thereby improving the bandwidth of the direct modulation laser chip.

[0021] (2) The optical coupling structure adopts a self-focusing lens plus isolator, which reduces the volume occupied by the optical path and is easier to adjust. It has the advantages of simple structure, high bandwidth and small size, and can be applied to the development of high-speed laser modules. Attached Figure Description

[0022] The above-described features, other objects, and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0023] Figure 1 A schematic top view of a laser bandwidth compensation integrated structure according to an embodiment of the present invention is shown.

[0024] Figure 2 A schematic left view of a laser bandwidth compensation integrated structure according to an embodiment of the present invention is shown.

[0025] Figure 3 A top view schematically illustrates another laser bandwidth compensation integrated structure according to an embodiment of the present invention; and

[0026] Figure 4The schematic diagram illustrates a structure of a laser emitting module according to an embodiment of the present invention.

[0027] Figure label:

[0028] 1-Microwave circuit; 11-High-frequency circuit; 111-Capacitor compensation structure; 112-DC electrode; 113-Thin film resistor; 114-Coplanar waveguide structure; 115-Transition transmission line; 116-Straight transmission line; 12-DC bias circuit; 121-High-frequency tapered inductor; 122-Thermistor; 13-Metal via; 14-Side metallization structure; 2-Laser chip; 3-Optical coupling structure; 31-Self-focusing lens; 32-Isolator; 33-Fiber optic assembly; 34-Heat sink; 35-Ω bracket; 36-Semiconductor cooler; 4-High-frequency laser housing; 41-Optical emission interface; 42-RF interface; 43-DC pin; 5-Gold wire; 6-Edge circuit. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0030] Figure 1 A top view of a laser bandwidth compensation integrated structure according to an embodiment of the present invention is shown schematically, and its left view is as follows. Figure 2 As shown.

[0031] Depend on Figure 1 and Figure 2As can be seen, a laser bandwidth compensation integrated structure according to an embodiment of the present invention includes: a microwave circuit 1, a laser chip 2, and an optical coupling structure 3. The microwave circuit 1 includes a high-frequency circuit 11 and a DC bias circuit 12. The high-frequency circuit 11 is used to transmit radio frequency signals from outside the laser bandwidth compensation integrated structure to the laser chip 2. The high-frequency circuit 11 includes a capacitor compensation structure 111, which is disposed at the end of the high-frequency circuit 11. By adding capacitive pad stubs, it compensates for the parasitic inductance generated by the bonding lines between the laser chip 2 and the microwave circuit 1, thereby improving the bandwidth of the laser chip 2. The DC bias circuit 12 is used to provide bias current to the laser chip 2. The laser chip 2 is correspondingly disposed with the microwave circuit 1 and is used to directly modulate an electrical signal onto an optical signal to output an optical signal, wherein the electrical signal includes a radio frequency signal. The optical coupling structure 3 is correspondingly disposed with the laser chip 2 and is used to transmit the optical signal to the outside of the laser bandwidth compensation integrated structure. Optionally, the high-frequency circuit 11 further includes a DC electrode 112 for providing a DC electrical signal to the laser chip 2. Optionally, the laser chip 2 includes either a three-segment direct modulation laser chip or a single-electrode direct modulation laser chip.

[0032] In some exemplary embodiments, the laser bandwidth compensation integrated structure also includes a thermistor 122, which is disposed on one side close to the laser chip 2 for monitoring the operating temperature of the laser chip 2; and a semiconductor cooler 36, which is disposed at the bottom of the heat sink 34 for working together with the thermistor 122 to achieve stable control of the operating temperature of the laser chip 2.

[0033] In some exemplary embodiments, the laser bandwidth compensation integrated structure further includes: a laser high-frequency housing 4, disposed outside the laser chip 2 and the microwave circuit 1. Optionally, the laser high-frequency housing 4 includes: a light emission interface 41, disposed on the laser high-frequency housing 4, for allowing light signals to pass through and be transmitted to the outside of the laser high-frequency housing 4; a radio frequency interface 42, disposed on the outer surface of the laser high-frequency housing 4, for inputting external radio frequency signals into the high-frequency circuit 11; and a DC pin 43, disposed on the outer surface of the laser high-frequency housing 4, for providing bias current to the laser chip 2 and current to the thermistor 122 and the thermoelectric cooler 36.

[0034] In this embodiment of the invention, the high-frequency circuit 11 has a coplanar waveguide structure 114. Optionally, the structure of the high-frequency circuit 11 includes one of a microstrip line structure, a stripline structure, or a differential transmission line structure. Optionally, when the structure of the high-frequency circuit 11 is a coplanar waveguide structure 114, a microstrip line structure, or a stripline structure, its characteristic impedance is 50 ohms; when the structure of the high-frequency circuit 11 is a differential transmission line structure, its characteristic impedance is 100 ohms.

[0035] In some exemplary embodiments, the microwave circuit 1 further includes: a metal via 13 disposed on the surface of the microwave circuit 1 for eliminating resonance phenomena in the high-frequency circuit 11; and a side metallization structure 14 disposed on the side of the high-frequency circuit 11 for connecting the ground electrodes of the upper and lower surfaces of the high-frequency circuit 11. In this embodiment of the invention, the side metallization structure 14 is used to connect the ground electrodes of the upper and lower surfaces of the coplanar waveguide structure 114.

[0036] In some exemplary embodiments, the radio frequency electrode of the laser chip 2 is connected to the signal line of the high-frequency circuit 11; the DC electrode 112 of the laser chip 2 is connected to the DC electrode 112 of the high-frequency circuit 11; and the N-pole of the electrode of the laser chip 2 is connected to the ground electrode of the microwave circuit 1.

[0037] In some exemplary embodiments, the microwave circuit 1 is provided with components to optimize the circuit structure. The high-frequency circuit 11 includes a thin-film resistor 113, which is connected in series in the high-frequency circuit 11 to achieve impedance matching. The DC bias circuit 12 includes a high-frequency tapered inductor 121, which is connected in series in the DC bias circuit 12 to prevent high-frequency signal leakage. Optionally, the high-frequency inductor is directly disposed above the signal line of the high-frequency circuit 11 to minimize the length of the inductor lead.

[0038] In some exemplary embodiments, the optical coupling structure 3 includes: a self-focusing lens 31, disposed after the light-emitting surface of the laser chip 2, used to match the optical signal output by the laser with the numerical aperture of the optical fiber to reduce the power loss of the optical signal; an isolator 32, disposed after the self-focusing lens 31, used to reduce the reflected light from the end faces of each component, preventing the reflected light from being injected back into the laser chip 2 and causing nonlinear effects, thereby ensuring the modulation and spectral characteristics of the laser; and an optical fiber assembly 33, corresponding to the optical emission interface 41, with the end face of the optical fiber assembly 33 tilted at an octave angle to reduce the reflection of reflected light in the fiber core, thereby reducing return loss. Optionally, the centers of the self-focusing lens 31, the isolator 32, and the optical fiber assembly 33 are on the same horizontal line to reduce the loss of the optical signal.

[0039] In this embodiment of the invention, the self-focusing lens 31, the isolator 32 and the optical fiber assembly 33 are aligned on the same horizontal line by heat sinks 34 and Ω brackets 35 with different bottom heights, so as to reduce the loss of optical signal.

[0040] Figure 3 A top view of another laser bandwidth compensation integrated structure according to an embodiment of the present invention is shown schematically.

[0041] Depend on Figure 3 It can be seen that, according to another embodiment of the present invention, the laser bandwidth compensation integrated structure is in Figure 1 and Figure 2 Based on the laser bandwidth compensation integrated structure shown, the high-frequency circuit 11 in the microwave circuit 1 adopts two transmission lines, and the laser chip 2 includes a direct-modulation laser chip 2 with a single electrode.

[0042] In this embodiment of the invention, the high-frequency circuit 11 includes a transition transmission line 115 and a straight transmission line 116. The transition transmission line 115 is used to convert the coaxial transmission line into a coplanar structure, completing the transmission of radio frequency signals from the outside of the laser high-frequency housing 4 to the straight transmission line 116. The transition transmission line 115 includes: a coplanar waveguide structure 114, which optionally includes a microstrip line structure, a stripline structure, or a differential transmission line structure. Optionally, the characteristic impedance of the coplanar waveguide structure 114, the microstrip line structure, or the stripline structure is 50 ohms, and the characteristic impedance of the differential transmission line structure is 100 ohms; a capacitor compensation structure 111, which compensates for the parasitic inductance generated by the bonding wire between the laser and the microwave circuit 1 through capacitive pad stubs, thereby improving the bandwidth of the direct modulation laser chip 2; a metal via 13, used to eliminate resonance phenomena in the high-frequency circuit 11; and a side metallization structure 14, used to connect the ground electrodes on the upper and lower surfaces of the coplanar waveguide structure 114.

[0043] In this embodiment of the invention, the straight transmission line 116 serves as the carrier of the laser chip 2, used to transmit radio frequency signals from the transition transmission line 115 to the laser chip 2. Further, the straight transmission line 116 includes: a coplanar waveguide structure 114, optionally comprising a microstrip line structure, a stripline structure, or a differential transmission line structure. Optionally, the characteristic impedance of the microstrip line structure or stripline structure is 50 ohms, and the characteristic impedance of the differential transmission line structure is 100 ohms; a capacitor compensation structure 111, which compensates for the parasitic inductance generated by the bonding wires between the laser and the microwave circuit 1 through capacitive pad stubs, thereby improving the bandwidth of the directly modulated laser chip 2; a side metallization structure 14, used to connect the ground electrodes on the upper and lower surfaces of the coplanar waveguide structure 114; and a series thin-film resistor 113, used to achieve impedance matching in the high-frequency circuit 11.

[0044] In this embodiment of the invention, the signal line and ground line spacing at the junction of the transition transmission line 115 and the straight transmission line 116 correspond to each other, and the transition transmission line 115 and the straight transmission line 116 are interconnected by multiple gold wires 5, thereby reducing the parasitic effect introduced by the gold wires 5.

[0045] Other parts of the laser bandwidth compensation integrated structure according to embodiments of the present invention are... Figure 1 and Figure 2 The same implementation examples will not be repeated here.

[0046] Figure 4 The schematic diagram illustrates a structure of a laser emitting module according to an embodiment of the present invention.

[0047] Depend on Figure 4 As can be seen, a laser emitting module according to an embodiment of the present invention includes the above-mentioned laser bandwidth compensation integrated structure, wherein the radio frequency electrode of the laser chip 2 is connected to the signal line of the high frequency circuit 11 of the microwave circuit 1, the DC electrode 112 of the laser chip 2 is connected to the DC electrode 112 of the microwave circuit 1, and the N pole of the electrode of the laser chip 2 is connected to the ground electrode of the microwave circuit 1.

[0048] In this embodiment of the invention, the high-frequency circuit 11 of the laser bandwidth compensation integrated structure adopts a coplanar waveguide structure 114. In the connection process between the laser chip 2 and the signal line of the high-frequency circuit 11, parasitic parameters are compensated by controlling the length of the connecting gold wire 5 to optimize the device performance. Components are provided on the microwave circuit 1 to optimize the circuit structure. Impedance matching is achieved by setting a series thin-film resistor 113 in the high-frequency circuit 11, where the series resistor is 25Ω. A high-frequency tapered inductor 121 is connected in series in the DC bias circuit 12 to prevent high-frequency signal leakage. This high-frequency inductor is directly placed above the signal line of the high-frequency circuit 11, minimizing the length of the inductor lead. In the interconnection between the laser bandwidth compensation integrated structure and the internal pins of the laser high-frequency housing 4, an edge circuit 6 is used as a transition to avoid contact or breakage due to excessive length of the gold wire 5. The laser bandwidth compensation integrated structure and the edge circuit 6, as well as the edge circuit 6 and the internal pins of the laser high-frequency housing 4, are connected by gold wire 5, gold strip, or flip-chip bonding.

[0049] In summary, this invention provides a laser bandwidth compensation integrated structure and a laser emitting module. By adding capacitive pad stubs to the microwave circuit 1, i.e., coupling capacitors, the parasitic inductance generated by the bonding lines between the laser and the microwave circuit 1 is compensated, thereby improving the bandwidth of the directly modulated laser chip 2. The optical coupling structure 3 uses a self-focusing lens 31 and an isolator 32, which reduces the volume occupied by the optical path and makes it easier to adjust. It has the advantages of simple structure, high bandwidth, and small size, and can be applied to the development of high-speed laser modules.

[0050] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A laser bandwidth compensation integrated structure, characterized in that, include: Microwave circuits, laser chips, and optical coupling structures. The microwave circuit includes a high-frequency circuit and a DC bias circuit. The high-frequency circuit transmits radio frequency signals from outside the laser bandwidth compensation integrated structure to the laser chip. The high-frequency circuit includes a capacitor compensation structure and a DC electrode. The capacitor compensation structure is located at the end of the high-frequency circuit and improves the bandwidth of the laser chip by compensating for the parasitic inductance generated by the bonding wires between the laser chip and the microwave circuit. The DC electrode provides a DC signal to the laser chip. The DC bias circuit provides a bias current to the laser chip. The laser chip is configured correspondingly to the microwave circuit, and is used to directly modulate an optical signal by loading an electrical signal onto it to output an optical signal, wherein the electrical signal includes the radio frequency signal; and The optical coupling structure is configured correspondingly to the laser chip and is used to transmit the optical signal to the outside of the laser bandwidth compensation integrated structure.

2. The laser bandwidth compensation integrated structure according to claim 1, characterized in that, Also includes: A thermistor, located on the side close to the laser chip, is used to monitor the operating temperature of the laser chip. as well as Semiconductor coolers are used in conjunction with thermistors to achieve stable control of the operating temperature of laser chips.

3. The laser bandwidth compensation integrated structure according to claim 2, characterized in that, Also includes: A high-frequency laser housing is disposed outside the laser chip and the microwave circuit. The high-frequency housing of the laser includes: An optical emission interface is provided on the high-frequency housing of the laser to allow the optical signal to pass through and be transmitted to the outside of the high-frequency housing of the laser. A radio frequency (RF) interface, disposed on the outer surface of the high-frequency housing of the laser, is used to input external RF signals into the high-frequency circuit; and A DC pin, located on the outer surface of the high-frequency housing of the laser, is used to provide bias current to the laser chip and to provide current to the thermistor and the thermoelectric cooler.

4. The laser bandwidth compensation integrated structure according to claim 1, characterized in that, The structure of the high-frequency circuit includes one of the following: coplanar waveguide structure, microstrip line structure, stripline structure, or differential transmission line structure.

5. The laser bandwidth compensation integrated structure according to claim 1, characterized in that, The microwave circuit also includes: Metal vias, disposed on the surface of the microwave circuit, are used to eliminate resonance phenomena in the high-frequency circuit; and A side-metallized structure is disposed on the side of the high-frequency circuit and is used to connect the ground electrode of the upper and lower surfaces of the high-frequency circuit.

6. The laser bandwidth compensation integrated structure according to claim 1, characterized in that, The radio frequency electrode of the laser chip is connected to the signal line of the high-frequency circuit. The DC electrode of the laser chip is connected to the DC electrode of the high-frequency circuit; and The N-pole of the laser chip's electrode is connected to the ground electrode of the microwave circuit.

7. The laser bandwidth compensation integrated structure according to claim 1, characterized in that, The high-frequency circuit includes a thin-film resistor connected in series in the high-frequency circuit to achieve impedance matching; and The DC bias circuit includes a high-frequency tapered inductor connected in series in the DC bias circuit to prevent high-frequency signal leakage.

8. The laser bandwidth compensation integrated structure according to claim 3, characterized in that, The optical coupling structure includes: A self-focusing lens is disposed after the light-emitting surface of the laser chip to match the optical signal output by the laser chip with the numerical aperture of the optical fiber, so as to reduce the power loss of the optical signal. An isolator, positioned after the self-focusing lens, is used to reduce reflected light from the end faces of each component, preventing the reflected light from injecting into the laser chip and causing nonlinear effects, thereby ensuring the modulation and spectral characteristics of the laser; and The optical fiber assembly is configured to correspond to the optical emission interface, and the end face of the optical fiber assembly is tilted at an octave angle to reduce the reflection of reflected light in the fiber core, thereby reducing return loss.

9. The laser bandwidth compensation integrated structure according to claim 8, characterized in that, The centers of the self-focusing lens, the isolator, and the optical fiber assembly are on the same horizontal line.

10. A laser emitting module, characterized in that, Includes the laser bandwidth compensation integrated structure as described in any one of claims 1 to 9.

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