A single-arm modulator and method for generating frequency-modulated continuous waves.

Abstract

This invention provides a single-arm modulator and method for generating frequency-modulated continuous waves, belonging to the field of semiconductor laser technology. This invention achieves frequency modulation of light through phase modulation. An applied electrical signal generates a time-varying electric field on the modulator waveguide structure, thereby causing a phase change in the incident light propagating in the single-arm modulator through an electro-optic effect, which in turn leads to a change in the incident light frequency. This solution is simple in structure, small in size, low in cost, and easily integrated with laser light sources.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor laser technology, and specifically relates to a single-arm modulator and method for generating frequency-modulated continuous waves. Background Technology

[0002] FMCW stands for Frequency Modulated Continuous Waves, which is a continuous optical signal whose frequency changes over time. It is used in high-precision radar ranging. Compared with traditional pulsed laser signals, FMCW has a longer detection range, higher resolution, and stronger anti-interference capability.

[0003] The methods for achieving FMCW are divided into internal modulation technology and external modulation technology. External modulation technology involves the laser and modulator working together to generate FMCW. The laser generates a beam of light with a stable frequency, which is then transmitted to the modulator and modulated by the modulator before being transmitted out as FMCW.

[0004] Currently, existing technologies use modulators with a dual parallel Mach-Zehnder structure to generate FMCW using single-sideband modulation. However, this modulator structure is relatively complex, has high insertion loss, large size, and is difficult to integrate with the light source. This inevitably increases the overall size and cost of the vehicle-mounted LiDAR, hindering miniaturization. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a single-arm modulator and method for generating frequency-modulated continuous waves.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A single-arm modulator for generating frequency-modulated continuous waves includes a modulator body, the modulator body comprising:

[0008] The chip body has a single-ridge straight waveguide structure formed by etching; this serves as the transmission path for the input laser.

[0009] Radio frequency traveling wave electrodes are disposed on the chip body;

[0010] A bias electrode is disposed on the chip body; the changing electric field between the bias electrode and the radio frequency traveling wave electrode acts on the input laser to generate output optical signals of different frequencies.

[0011] Preferably, the modulator body further includes:

[0012] The chip body is formed by epitaxial growth on the substrate material.

[0013] Preferably, the chip body includes:

[0014] The layers are stacked from bottom to top: an n-type confinement layer, a semiconductor material core layer, and a p-type confinement layer.

[0015] Two dielectric layers are respectively disposed between the n-type confinement layer and the semiconductor material core layer, and between the semiconductor material core layer and the p-type confinement layer.

[0016] Preferred,

[0017] The radio frequency traveling wave electrode is disposed at the top of the p-confining layer and connected to the p-confining layer;

[0018] The bias electrode is disposed at one end away from the semiconductor material core layer and is connected to the n-confining layer.

[0019] Preferred,

[0020] Mesa surfaces are formed on the substrate and the n-type confinement layer by etching.

[0021] Preferred,

[0022] Mesa surfaces are formed on the n-type confinement layer, the semiconductor material core layer, and the p-type confinement layer by etching.

[0023] Preferably, the material of the single-ridge straight waveguide structure is the same as the material of the dielectric layer of the chip body.

[0024] Preferably, the material of the single-ridge straight waveguide structure is a semiconductor material.

[0025] Preferably, the two ends of the single-ridge straight waveguide structure are the light inlet for input laser light and the light outlet for output optical signal light, respectively.

[0026] A method for generating frequency-modulated continuous waves includes the following steps:

[0027] Incident light enters the single-ridge straight waveguide structure;

[0028] The bias electrode and the radio frequency traveling wave electrode of the time-varying electrical signal work together to generate a time-varying electric field on the single-ridge straight waveguide structure. Through the electro-optic effect, the incident light produces a phase change in the single-ridge straight waveguide structure.

[0029] By utilizing the relationship between the phase of the incident light and the optical frequency, the optical phase change corresponding to the frequency-modulated continuous wave can be calculated.

[0030] Frequency-modulated continuous waves are generated according to the optical phase changes corresponding to the frequency-modulated continuous wave.

[0031] The single-arm modulator and method for generating frequency-modulated continuous waves provided by this invention have the following beneficial effects: This invention achieves frequency modulation of light by modulating the phase. Utilizing the differential-integral relationship between light phase and light frequency, the phase change corresponding to the frequency-modulated continuous wave is calculated, and the light phase is modulated according to this phase change to generate the corresponding frequency-modulated continuous wave. When incident light propagates in the single-arm modulator, the phase change of the light is controlled by a time-varying electrical signal applied to the traveling wave electrode. The applied electrical signal generates a time-varying electric field on the modulator waveguide structure, thereby causing a phase change in the incident light propagating in the single-arm modulator through the electro-optic effect, which in turn leads to a change in the incident light frequency. By controlling the applied electrical signal to control the phase change and thus the frequency change, various waveforms of frequency-modulated continuous waves can be generated. This invention uses a single-arm modulator to directly modulate the light frequency using phase modulation. Compared with existing single-sideband modulation technology using dual parallel Mach-Zehnder modulators, this reduces structural complexity, size, and cost, directly contributing to miniaturization. Attached Figure Description

[0032] To more clearly illustrate the embodiments and design schemes of the present invention, the accompanying drawings required for this embodiment will be briefly described below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a structural diagram of a single-arm modulator for generating frequency-modulated continuous waves according to Embodiment 1 of the present invention;

[0034] Figure 2 This is a left view of a single-arm modulator for generating frequency-modulated continuous waves according to Embodiment 1 of the present invention.

[0035] Figure 3 This is a front view of a single-arm modulator for generating frequency-modulated continuous waves according to Embodiment 1 of the present invention.

[0036] Figure 4 This is a frequency-modulated continuous triangular wave with a frequency shift of 15 GHz, as described in Embodiment 1 of the present invention.

[0037] Figure 5 This refers to the phase change corresponding to the frequency-modulated continuous triangular wave with a frequency shift of 15 GHz in Embodiment 1 of the present invention.

[0038] Explanation of reference numerals in the attached figures:

[0039] 11. Modulator body; 12. Radio frequency traveling wave electrode; 13. Bias electrode; 14. Mesa; 15a. Light inlet; 15b. Light outlet; 111. Substrate; 112. n-type confinement layer; 113. Semiconductor material core layer; 114. p-type confinement layer. Detailed Implementation

[0040] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0041] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0042] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "connected" or "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, which will not be elaborated further here.

[0043] Example 1

[0044] See Figures 1-3 The present invention discloses a single-arm modulator for generating frequency-modulated continuous waves, including a modulator body 11, which includes a chip body, an RF traveling wave electrode 12, a bias electrode 13, and a substrate material 111.

[0045] The chip body is epitaxially grown on an InP substrate 111. A single-ridge straight waveguide structure is formed on the chip body through etching, serving as the transmission path for the input laser. The chip body includes an n-type confinement layer 112, a semiconductor core layer 113, a p-type confinement layer 114, and two dielectric layers. The n-type confinement layer 112, the semiconductor core layer 113, and the p-type confinement layer 114 are stacked sequentially from bottom to top. The two dielectric layers are respectively disposed between the n-type confinement layer 112 and the semiconductor core layer 113, and between the semiconductor core layer 113 and the p-type confinement layer 114. Mesa 14 is formed on the InP substrate 111 and the n-type confinement layer 112 through etching. Mesa 14 is also formed on the n-type confinement layer 112, the semiconductor core layer, and the p-type confinement layer 114 through etching.

[0046] A radio frequency (RF) traveling-wave electrode 12 is disposed at the top of the p-confinement layer and connected to the p-confinement layer. A bias electrode 13 is disposed at the end away from the semiconductor core layer 113 and connected to the n-confinement layer. The changing electric field between the bias electrode 13 and the RF traveling-wave electrode 12 acts on the input laser, generating output optical signals of different frequencies. Specifically, the RF traveling-wave electrode 12 on the modulator is connected to an RF signal, and the bias electrode 13 is connected to a DC bias signal, causing a time-varying electric field to be generated at the waveguide. After the incident light signal passes through the single-arm modulator, the phase of the output light signal changes with time.

[0047] In this embodiment, the material of the single-ridge straight waveguide structure is the same as the dielectric layer material of the chip body or a semiconductor material. Furthermore, the two ends of the single-ridge straight waveguide structure are the input port 15a for the input laser and the output port 15b for the output optical signal, respectively.

[0048] See Figure 4 and Figure 5 , Figure 4 A frequency-modulated continuous triangular wave shifted by 15 GHz. Figure 5 This describes the phase change corresponding to a frequency-modulated continuous triangular wave shifted by 15 GHz. Based on the relationship that frequency and phase are mutually differential and integral, the phase change of the frequency-modulated continuous triangular wave when the wavelength of 1550 nm is shifted by 15 GHz is calculated. The electrical signal applied to the traveling wave electrode is then controlled to adjust the phase of the incident light according to... Figure 5 The changes shown produce the following: Figure 4 The frequency-modulated continuous triangular wave shown is shown.

[0049] The present invention discloses a method for manufacturing a single-arm modulator that generates a frequency-modulated continuous wave as follows: a modulator body 11 is epitaxially grown on an InP substrate 111 material; the chip body is etched to form two mesa 14 on the chip body; the chip body is etched to form a single-ridge straight waveguide on the chip body; a radio frequency traveling wave electrode 12 is formed on the top of the p-type confinement layer, and a bias electrode 13 is formed on the portion of the n-type confinement layer away from the modulator body.

[0050] In this embodiment, a method for generating a frequency-modulated continuous wave is also included, specifically comprising the following steps: incident light enters a single-ridge straight waveguide structure; the bias electrode 13 and the radio frequency traveling wave electrode 12, which generates a time-varying electric field on the single-ridge straight waveguide structure, cause the incident light to undergo a phase change in the single-ridge straight waveguide structure through the electro-optic effect; the optical phase change corresponding to the frequency-modulated continuous wave is calculated using the differential-integral relationship between the phase of the incident light and the optical frequency; and the frequency-modulated continuous wave is generated according to the optical phase change corresponding to the frequency-modulated continuous wave.

[0051] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited thereto. Any simple changes or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. A single-arm modulator for generating frequency-modulated continuous waves, comprising a modulator body (11), characterized in that, The modulator body (11) includes: The chip body has a single-ridge straight waveguide structure formed by etching on the chip body; this serves as the transmission path for transmitting the input laser. Radio frequency traveling wave electrode (12) is disposed on the chip body; A bias electrode (13) is disposed on the chip body; the changing electric field between the bias electrode (13) and the radio frequency traveling wave electrode (12) acts on the input laser to generate output light signals of different frequencies; The modulator body (11) also includes: The chip body is formed by epitaxial growth of the substrate (111) material; The chip body includes: The layers stacked from bottom to top are an n-type confinement layer (112), a semiconductor material core layer (113), and a p-type confinement layer (114); Two dielectric layers are respectively disposed between the n-type confinement layer (112) and the semiconductor material core layer (113) and between the semiconductor material core layer (113) and the p-type confinement layer (114); The radio frequency traveling wave electrode (12) is disposed at the top of the p-type confinement layer and connected to the p-type confinement layer; The bias electrode (13) is disposed at one end away from the semiconductor material core layer (113) and is connected to the n-type confinement layer.

2. The single-arm modulator for generating frequency-modulated continuous waves according to claim 1, characterized in that, Mesa (14) is formed on the substrate (111) and the n-type confinement layer (112) by etching.

3. The single-arm modulator for generating frequency-modulated continuous waves according to claim 1, characterized in that, Mesa (14) is formed by etching on the n-type confinement layer (112), the semiconductor material core layer and the p-type confinement layer (114).

4. The single-arm modulator for generating frequency-modulated continuous waves according to claim 1, characterized in that, The material of the single-ridge straight waveguide structure is a semiconductor material.

5. The single-arm modulator for generating frequency-modulated continuous waves according to claim 1, characterized in that, The two ends of the single-ridge straight waveguide structure are the light inlet (15a) for input laser light and the light outlet (15b) for output optical signal light.

6. A method for generating a frequency-modulated continuous wave using a single-arm modulator according to any one of claims 1-5, characterized in that, Includes the following steps: Incident light enters the single-ridge straight waveguide structure; The bias electrode (13) and the radio frequency traveling wave electrode (12) of the time-varying electrical signal work together to generate a time-varying electric field on the single-ridge straight waveguide structure. Through the electro-optic effect, the incident light generates a phase change in the single-ridge straight waveguide structure. By utilizing the relationship between the phase of the incident light and the optical frequency, the optical phase change corresponding to the frequency-modulated continuous wave can be calculated. Frequency-modulated continuous waves are generated according to the optical phase changes corresponding to the frequency-modulated continuous wave.

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