Strip line feed-in directly modulated laser

Abstract

The utility model discloses a strip line feed-in directly modulated laser, which comprises two parallel ceramic circuit boards, a ceramic dielectric layer is clamped between the two groups of ceramic circuit boards, the ceramic circuit boards and the ceramic dielectric layer form a microstrip line, and a metal layer is arranged on the inner surface of each ceramic circuit board to form a closed radio frequency transmission line. The ceramic dielectric layer is clamped between the two parallel ceramic circuit boards to form the closed microstrip line structure, and the laser chip is embedded in the microstrip line, so that direct feed-in of radio frequency signals is realized, gold wire connection is not needed, parasitic parameter influence caused by gold wires is eliminated fundamentally, and the service life of the laser is prolonged. The microstrip line is designed in a closed mode, electromagnetic waves are effectively prevented from being diffused to the surrounding space, radiation loss in the signal transmission process is reduced, meanwhile, the crosstalk risk between adjacent circuits is reduced, and the overall performance and reliability of a system are improved.

Description

Technical Field

[0001] This utility model relates to the field of microwave photonics technology, specifically to a stripline-fed direct-modulation laser. Background Technology

[0002] As a core device in the field of microwave photonics, directly modulated lasers are widely used in optical modulation and transmission of high-frequency radio frequency signals. Currently, the radio frequency signal feed of directly modulated lasers is mostly achieved by microstrip lines or coplanar waveguide structures. For example, microstrip lines form a transmission path through a combination of metal wires and dielectric substrates, while coplanar waveguides utilize the coplanar design of the central guide strip and the ground planes on both sides to transmit radio frequency signals.

[0003] When traditional microstrip lines or coplanar waveguides connect lasers and radio frequency signal sources, they rely on gold wire bonding technology to complete the electrical interconnection. Although gold wire bonding can establish a physical connection, it will introduce significant parasitic inductance and capacitance in the radio frequency path. Such parasitic parameters will cause signal path impedance mismatch at high frequencies (such as millimeter wave bands), which will lead to problems such as signal reflection, attenuation and bandwidth limitation.

[0004] Secondly, as a semi-open transmission line structure, the coplanar waveguide has inherent defects in its electromagnetic field distribution. Specifically, the electromagnetic energy of the coplanar waveguide is partially distributed in the interface region between the dielectric substrate and the air, causing the electromagnetic field to diffuse into the surrounding space. This leakage phenomenon not only causes energy loss, but also generates electromagnetic coupling with adjacent circuits or devices, causing crosstalk problems. In severe cases, it can even lead to signal waveform distortion. Therefore, we need to propose a stripline-fed direct-modulation laser. Utility Model Content

[0005] The purpose of this invention is to provide a stripline-fed direct-modulation laser. By using two parallel ceramic circuit boards sandwiching a ceramic dielectric layer to form a closed microstrip line structure, and embedding the laser chip inside the microstrip line, the direct feeding of radio frequency signals is achieved without the need for gold wire connections, thereby solving the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A stripline-fed direct-modulation laser includes: two parallel ceramic circuit boards, a ceramic dielectric layer sandwiched between the two sets of ceramic circuit boards, and the ceramic circuit boards and the ceramic dielectric layer forming a microstrip line.

[0008] The inner surface of the ceramic circuit board is provided with a metal layer to form a closed radio frequency transmission line;

[0009] A laser chip, wherein the laser chip is embedded inside a microstrip line, and the electrodes of the laser chip are directly connected to an RF signal input port for feeding RF signals through the metal layer;

[0010] The microstrip line is arranged in a closed configuration.

[0011] Preferably, the ceramic circuit board is made of alumina, and the dielectric constant of the ceramic dielectric layer is 8.5 to 10.5.

[0012] Preferably, the laser chip is fixed inside the microstrip line by flip-chip bonding, and the radio frequency input electrode of the laser chip is electrically connected to the metal layer through pads.

[0013] Preferably, the metal layer is made of copper with a thickness of 10–50 μm, and the metal layer extends to the edge of the microstrip line to form a shielded grounding terminal.

[0014] Preferably, the length of the microstrip line is matched with the wavelength of the operating frequency, specifically satisfying λ / 4≤L≤λ / 2.

[0015] Preferably, the thickness of the ceramic dielectric layer is 0.1 to 0.5 mm, and the surface of the ceramic dielectric layer is provided with a microporous structure.

[0016] Preferably, the input end of the microstrip line is provided with an impedance matching network, which is composed of capacitors and inductors integrated on a ceramic circuit board.

[0017] Compared with the prior art, the beneficial effects of this utility model are:

[0018] 1. This utility model uses two parallel ceramic circuit boards sandwiching a ceramic dielectric layer to form a closed microstrip line structure, and embeds the laser chip inside the microstrip line, realizing direct feeding of radio frequency signals without the need for gold wire connection. This fundamentally eliminates the influence of parasitic parameters caused by gold wire, and significantly improves the transmission efficiency and stability of radio frequency signals.

[0019] 2. The microstrip line adopts a closed design, which effectively prevents electromagnetic waves from spreading into the surrounding space, reduces radiation loss during signal transmission, and reduces the risk of crosstalk between adjacent circuits, thereby improving the overall performance and reliability of the system. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of this utility model;

[0021] Figure 2 This is a schematic diagram of the structure of the ceramic circuit board, ceramic dielectric layer and laser chip of this utility model;

[0022] Figure 3 This is a schematic diagram of the structure of the ceramic circuit board and metal layer of this utility model.

[0023] In the figure: 1. Ceramic circuit board; 2. Ceramic dielectric layer; 3. Microstrip line; 4. Laser chip; 5. Microhole structure; 6. Metal layer. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] Please see Figure 1-3 This utility model provides a technical solution:

[0026] A stripline-fed direct-modulation laser achieves efficient and stable transmission of radio frequency signals through a unique design. Specifically, the direct-modulation laser includes two parallel ceramic circuit boards 1. These two ceramic circuit boards 1 are made of high-purity alumina material, which has good insulation performance and mechanical strength, ensuring the stable operation of the laser in complex environments. A ceramic dielectric layer 2 is sandwiched between the two sets of ceramic circuit boards 1, and the ceramic circuit boards 1 and the ceramic dielectric layer 2 form a microstrip line 3.

[0027] A metal layer 6 is provided on the inner surface of the ceramic circuit board 1 to form a closed radio frequency transmission line. The metal layer 6 is made of highly conductive copper material and the thickness is controlled between 10 and 50 μm. This ensures good conductivity and avoids signal attenuation caused by an excessively thick metal layer. The metal layer 6 not only forms a closed radio frequency transmission line, effectively preventing electromagnetic wave leakage, but also extends to the edge of the microstrip line 3 to form a shielded ground terminal, further enhancing the anti-interference capability.

[0028] Laser chip 4 is embedded inside microstrip line 3. The electrodes of laser chip 4 are directly connected to the radio frequency signal input port for feeding radio frequency signals through metal layer 6, which ensures that radio frequency signals can be transmitted to laser chip 4 efficiently and stably.

[0029] The microstrip line 3 is enclosed, which effectively prevents electromagnetic waves from spreading into the surrounding space and reduces radiation loss during signal transmission. At the same time, the length of the microstrip line 3 is strictly matched with the wavelength of the operating frequency, specifically satisfying the condition λ / 4≤L≤λ / 2. This design enables the microstrip line 3 to have the best transmission performance at the operating frequency. The metal layer 6 of the enclosed microstrip line 3 and the shielding ground terminal form a Faraday cage effect, which can confine the electromagnetic field inside the transmission line, suppress electromagnetic leakage, and block external interference signals.

[0030] The ceramic circuit board 1 is made of alumina, and the dielectric constant of the ceramic dielectric layer 2 is 8.5–10.5. Alumina ceramic has high thermal conductivity (approximately 30 W / m·K), low dielectric loss (tanδ<0.0002), and excellent mechanical stability, which can meet the material performance requirements of high-frequency radio frequency transmission. By optimizing the dielectric constant range (8.5–10.5), lower signal attenuation and phase distortion can be achieved in the high-frequency band (e.g., 20–40 GHz).

[0031] The laser chip 4 is fixed inside the microstrip line 3 by flip-chip bonding. The RF input electrode of the laser chip 4 is electrically connected to the metal layer 6 through pads. This bonding method not only improves the stability of the connection, but also optimizes the transmission path of the RF signal. The pads are made of gold-tin alloy material, and the bonding temperature is controlled at 250-300℃ to ensure the reliability of the electrical connection and low contact resistance (<0.1Ω). The flip-chip bonding process directly aligns and bonds the chip electrode to the pad, avoiding the arc height problem of traditional gold wire bonding, significantly shortening the RF path length, reducing parasitic inductance (<0.1nH) and capacitance (<0.05pF), thereby improving the high-frequency signal transmission efficiency.

[0032] The metal layer 6 is made of copper and has a thickness of 30 μm. The metal layer 6 extends to the edge of the microstrip line 3 to form a shielded ground terminal. The ceramic dielectric layer 2 has a thickness of 0.1–0.5 mm. This thickness ensures sufficient mechanical strength while avoiding signal attenuation caused by an excessively thick dielectric layer. The surface of the ceramic dielectric layer 2 has a microporous structure 5 with a pore size of 20–50 μm and a pore density of 100–200 pores / cm³. 2 These microporous structures help to adjust the dielectric constant and thermal conductivity of the ceramic dielectric layer 2, further improving the performance of the direct-modulated laser. The micropores are formed by laser etching process to enhance heat dissipation and adjust the local dielectric constant.

[0033] The input terminal of microstrip line 3 is equipped with an impedance matching network, which consists of capacitors and inductors integrated on ceramic circuit board 1. By precisely adjusting the parameters of the capacitors and inductors, impedance matching between microstrip line 3 and RF signal source can be achieved, thereby reducing signal reflection and loss and improving signal transmission efficiency. Through wavelength matching design, signal reflection can be reduced and the operating bandwidth can be widened within the target frequency band to meet the needs of multi-band applications. By adjusting the LC parameters (such as increasing the inductance value with the number of turns of the helix), the matching network can achieve a standard impedance matching of 50Ω (VSWR <1.2), covering the 20-40GHz frequency band, effectively reducing insertion loss and improving signal transmission efficiency.

[0034] During operation, the radio frequency (RF) signal is fed into the microstrip line 3 through the RF signal input port. Due to the closed design of the microstrip line 3 and the excellent electromagnetic properties of the ceramic dielectric layer 2, the RF signal can be transmitted efficiently and stably in the microstrip line 3. When the RF signal is transmitted to the laser chip 4, the RF signal can directly act on the laser chip 4 through the electrical connection between the electrodes of the laser chip 4 and the metal layer 6, realizing direct modulation and conversion between optical signals and microwave signals. At the same time, the existence of the impedance matching network ensures minimal reflection and loss of the RF signal during transmission, further improving the overall performance of the direct-modulated laser.

[0035] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A direct modulated laser with stripline feed-in, characterized in that include: Two parallel ceramic circuit boards (1) are provided, and a ceramic dielectric layer (2) is sandwiched between the two sets of ceramic circuit boards (1). The ceramic circuit boards (1) and the ceramic dielectric layer (2) form a microstrip line (3). The inner surface of the ceramic circuit board (1) is provided with a metal layer (6) to form a closed radio frequency transmission line; Laser chip (4), the laser chip (4) is embedded inside the microstrip line (3), and the electrodes of the laser chip (4) are directly connected to the radio frequency signal input port for feeding radio frequency signals through the metal layer (6); The microstrip line (3) is arranged in a closed configuration.

2. A direct modulated laser with a stripline feed-in according to claim 1, characterized in that: The ceramic circuit board (1) is made of alumina, and the dielectric constant of the ceramic dielectric layer (2) is 8.5 to 10.

5.

3. A direct modulated laser with a stripline feed-in according to claim 1, characterized in that: The laser chip (4) is fixed inside the microstrip line (3) by flip-chip bonding, and the radio frequency input electrode of the laser chip (4) is electrically connected to the metal layer (6) through a pad.

4. A direct modulated laser with a stripline feed-in according to claim 1, characterized in that: The metal layer (6) is made of copper and has a thickness of 10 to 50 μm. The metal layer (6) extends to the edge of the microstrip line (3) to form a shielded grounding terminal.

5. A directly modulated laser fed by a stripline according to claim 1, characterized in that: The length of the microstrip line (3) is matched with the wavelength of the operating frequency, specifically satisfying λ / 4≤L≤λ / 2.

6. A directly modulated laser fed by a stripline according to claim 1, characterized in that: The thickness of the ceramic dielectric layer (2) is 0.1 to 0.5 mm, and the surface of the ceramic dielectric layer (2) is provided with a microporous structure (5).

7. A directly modulated laser fed by a stripline according to claim 1, characterized in that: The input terminal of the microstrip line (3) is provided with an impedance matching network, which is composed of capacitors and inductors integrated on a ceramic circuit board (1).

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