Ultrafast tunable precise laser emission light source

Abstract

The invention discloses an ultrafast tunable precise laser emission light source. The ultrafast tunable precise laser emission light source comprises an N-channel array laser chip based on a reconstruction equivalent chirp technology, an N-channel array Mach-Zehnder modulator and a coupler, n output ends of the array laser chip are correspondingly connected with N input ends of the array Mach-Zehnder modulator, and N output ends of the array Mach-Zehnder modulator are connected with the coupler; each output end of the array laser chip outputs laser with a DWDM standard wavelength, each laser beam enters a corresponding input end of the array Mach-Zehnder modulator, the array Mach-Zehnder modulator is used as a switch of the laser to modulate each laser beam, and the modulated laser beams are combined through the coupler. The Mach-Zehnder modulator is used as a switch to control different wavelength channels, fast, accurate and stable tuning can be achieved in a wide wavelength range, and meanwhile good output power and wavelength purity are kept.

Description

Technical Field

[0001] The present invention belongs to the fields of semiconductor laser array chip technology, phased array radar and optical switching technology, and specifically relates to an ultrafast tunable precision laser emission light source. Background Art

[0002] In the context of the rapid development of data-intensive applications, fast tunable lasers have become one of the core technologies for improving data transmission and processing capabilities. This type of laser can meet the rapidly changing needs of optical communications and achieve efficient and flexible optical signal transmission by quickly adjusting its output wavelength. The tuning speed of a tunable laser refers to the rate at which the laser changes its output wavelength, and is one of the key indicators for evaluating its performance.

[0003] Taking traditional temperature-controlled tunable lasers as an example, this type of laser achieves wavelength tuning by changing the ambient temperature of the laser, which has problems such as slow tuning speed, limited wavelength accuracy, and insufficient long-term stability. In addition, these traditional methods are often accompanied by large energy consumption and high costs when achieving wide-range tuning, which is not conducive to large-scale deployment and application.

[0004] Although the modulator can theoretically be used as a switch in a variety of optoelectronic applications, when passing through the Mach-Zehnder modulator, since light of different wavelengths has different refractive indices, the optical paths of optical signals on different paths have different optical paths and half-wave voltages. If only a unified tuning voltage is used, the input-output ratio of the modulator cannot be adjusted to the optimal state, and crosstalk will still occur between optical signals on different paths. Summary of the invention

[0005] In response to the above-mentioned problems, the present invention proposes an ultrafast tunable precision laser emission light source, which adds a wavelength influencing factor when adjusting the tuning voltage, controls the input-output ratio of the modulator, and achieves a better tuning effect; the present invention uses a Mach-Zehnder modulator as a switch to control different wavelength channels, which can achieve fast, precise and stable tuning in a wider wavelength range while maintaining good output power and wavelength purity.

[0006] An ultrafast tunable precision laser emission light source, comprising an N-channel array laser chip based on a reconstruction equivalent chirp technology, an N-channel array Mach-Zehnder modulator and a coupler; The N output ends of the array laser chip are connected to the N input ends of the array Mach-Zehnder modulator correspondingly, and the N output ends of the array Mach-Zehnder modulator are connected to the coupler; Each output end of the array laser chip outputs laser light of a DWDM standard wavelength, and each laser beam enters the corresponding input end of the array Mach-Zehnder modulator. The array Mach-Zehnder modulator acts as a laser switch to modulate each laser beam, and the modulated laser beams are combined through a coupler.

[0007] Furthermore, the array Mach-Zehnder modulator adjusts the radio frequency signal in real time according to the wavelength of the input laser to control the input-output ratio, so that the laser of the set channel is output to the coupler.

[0008] Furthermore, the multi-channel array laser chip calculates the period of the grating according to the following formula: ; Refractive index modulation amplitude of the grating part The refractive index modulation amplitude of the seed grating and the Fourier coefficients of the m-order sub-grating The relationship is as follows: In the formula is the output wavelength, is the equivalent refractive index in the waveguide, is the grating period, z is the position in the laser resonant cavity direction, is the variation of the sampling period.

[0009] Furthermore, the single-channel inference formula of the array Mach-Zehnder modulator satisfies the following conditions: Assume the input light field at time t and drive voltage They are: Additional phase caused by DC bias voltage for: Output light field after DC bias voltage for: , is the power distribution ratio of the two Y splitters. Under ideal conditions, , then the output power is: in is the amplitude of the input light field, and is the frequency and initial phase of light, V DCis the DC bias voltage, V RF is the amplitude of the driving voltage, and are the driving voltage frequency and initial phase respectively, The wavelength is The light in the phase modulator generates a voltage with an additional phase of π. is the input optical power of the Mach-Zehnder modulator; by controlling the DC bias of the Mach-Zehnder modulator The initial working point is set, and the RF signal V(t) is controlled to adjust the input-output ratio of the array Mach-Zehnder modulator, and the output of each channel is controlled to act as a switch.

[0010] Furthermore, photonic wire bonding technology is used to carry out heterogeneous integration of different materials, and photonic wires are used to transmit optical signals.

[0011] Furthermore, photon leads are prepared by two-photon exposure technology.

[0012] Furthermore, the array Mach-Zehnder modulator is a silicon-based Mach-Zehnder modulator.

[0013] Beneficial effects: First, the ultrafast tunable precision laser emission light source of the present invention replaces the tuning scheme of the traditional tunable laser by using an array Mach-Zehnder modulator as a switch, which can greatly improve the wavelength switching speed of the tunable laser. In the field of phased array radar, by quickly adjusting the wavelength of the laser, wide bandwidth and large angle scanning of the radar beam can be achieved, thereby improving the detection performance and flexibility of the radar; in the field of optical switching, by quickly adjusting the wavelength of the laser, dynamic routing of optical signals in the optical network can be achieved, thereby improving the flexibility and scalability of the network. Compared with traditional tunable lasers, the ultrafast tunable light source proposed by the present invention shows significant advantages in tuning speed, wavelength accuracy, power stability and energy efficiency, providing strong technical support for the improvement of the next generation of optical phased array radar and optical switching systems.

[0014] Second, the ultrafast tunable precision laser emission light source and the multi-channel array laser chip of the present invention use a processing technology of reconstructing equivalent chirp technology, which has the advantages of high wavelength accuracy and multi-channel output, can effectively reduce costs, and the chip has a high degree of integration, which is conducive to large-scale production and use.

[0015] Third, the ultrafast tunable precision laser emission source of the present invention uses photon wire bonding technology to couple devices of different materials, which has the advantages of high connection accuracy, small size, and low insertion loss. In addition, photon wire bonding technology does not require the use of harmful materials, which helps to improve the environmental friendliness of microelectronics manufacturing and avoids the complex and costly high-precision alignment technology in traditional optical assembly technology. The above characteristics meet the requirements of phased array radar and optical switching systems, and are expected to be widely used in coherent communication systems in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of an eight-channel array laser chip according to an embodiment of the present invention; Figure 2 This is a schematic diagram of an eight-channel ultrafast tunable laser emission light source according to an embodiment of the present invention; Figure 3 This is a structural diagram of an eight-channel ultrafast tunable laser emission light source chip according to an embodiment of the present invention; Figure 4 A schematic diagram of an output characteristic curve of a Mach-Zehnder modulator according to an embodiment of the present invention; Figure 5 This is an output spectrum diagram of eight-channel array lasers lit up simultaneously according to an embodiment of the present invention; Figure 6 Schematic diagram of wavelength switching effect according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The following examples will enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0018] The present invention discloses an ultrafast tunable precision laser emission light source, which comprises an N-channel array laser chip based on a reconstruction equivalent chirp technology, an N-channel array Mach-Zehnder modulator and a coupler; The N output ends of the array laser chip are connected to the N input ends of the array Mach-Zehnder modulator correspondingly, and the N output ends of the array Mach-Zehnder modulator are connected to the coupler; Each output end of the array laser chip outputs a laser of the DWDM standard wavelength. Each laser beam enters the corresponding input end of the array Mach-Zehnder modulator and is modulated by the array Mach-Zehnder modulator as a laser switch. The output of the array Mach-Zehnder modulator is combined through a coupler. The structure, preparation process and working principle of the ultrafast tunable precision laser emission light source of the present invention are further described below in conjunction with the accompanying drawings.

[0019] 1. Design and preparation of multi-channel array laser chips The design and preparation of multi-channel array laser chips are based on the reconstruction of equivalent chirp technology. The period of the grating is calculated according to the formula, which is necessary to ensure that the laser can oscillate stably within the target wavelength range: In order to flexibly realize various special structures required for high-performance semiconductor lasers, such as phase shift, chirp and toe cutting, in order to accurately calculate the equivalent phase shift and realize specific laser characteristics, the refractive index modulation amplitude of the grating part must be accurately calculated. The refractive index modulation amplitude of the seed grating and the Fourier coefficients F of the m-order sub-grating m The relationship is as follows: In the formula is the output wavelength, n eff is the equivalent refractive index in the waveguide, is the grating period, z is the position in the laser resonant cavity direction, is the variation of the sampling period.

[0020] 2. Design and fabrication of array Mach-Zehnder modulators First, design the array structure of the modulator, including waveguide layout, modulator distribution, and overall size; Next, select suitable electro-optical materials. Since the principle of the Mach-Zehnder modulator is to control the optical path of the waveguide by applying voltage, it is necessary to select materials with strong photoelectric effect. This patent uses silicon-based Mach-Zehnder modulators. Then, through etching, deposition and other steps, the waveguide and modulator structure are accurately produced to form a complete array Mach-Zehnder modulator. Finally, through testing and performance optimization, ensure the various performance indicators of the modulator.

[0021] 3. Heterogeneous integration of different materials Photonic wire bonding (PWB) is an emerging microelectronic packaging technology that uses photonic wires to connect optical devices of different materials to achieve efficient transmission of optical signals. It has the advantages of high precision, small size, and no need to use harmful materials. In this patent, PWB technology is used to achieve coupling between the laser and the Mach-Zehnder modulator. Due to the different materials of the laser and the modulator, their optical field mode field diameters (MFD) may be different. To ensure mode matching, this patent has carefully calculated and designed the shape of the photonic wire bonding between the laser and the modulator to gradually convert the size of the optical field and achieve efficient transmission of optical signals from one waveguide to another.

[0022] 4. Wavelength switching based on Mach-Zehnder modulator The structure of a Mach-Zehnder modulator usually includes an optical beam splitter and two optical waveguides. According to the principle of electro-optical effect, by changing the voltage on one waveguide, the phase of the optical signal in the optical waveguide can be changed, thereby modulating the amplitude of the optical signal through the interference effect. In tunable lasers, Mach-Zehnder modulators are used as key components for wavelength switching. Figure 4 The output characteristic curve of the Mach-Zehnder modulator is shown.

[0023] The single-channel inference formula of the array Mach-Zehnder modulator satisfies the following conditions: Assume that the input light field and driving voltage are: The additional phase caused by the DC bias voltage is: The output light field after DC bias voltage is: , is the power distribution ratio of the two Y splitters. For an ideal situation, , so the output power is: Where E0 is the amplitude of the input light field, and is the frequency and initial phase of light, V DC is the DC bias voltage, V RF is the amplitude of the driving voltage, and are the driving voltage frequency and initial phase respectively, The wavelength is The light in the phase modulator generates a voltage with an additional phase of π, also called half-wave voltage. is the input optical power of the Mach-Zehnder modulator.

[0024] By precisely controlling the voltage V(t) applied to the modulator, the input-output ratio of the Mach-Zehnder modulator can be changed, and then used as a switch to change the wavelength of the laser light source output. The wavelength of the laser output module is relatively small, so the laser output module can achieve fast wavelength switching. The specific switching process is as follows: in the initial state, one of the MZMs of the array Mach-Zehnder modulator is in the initial state, no external voltage is applied to the waveguide, the phase difference between the two arms is zero, and the amplitude of the output optical signal remains constant; while one of the waveguides of the remaining MZMs is acted upon by an external voltage, and due to the photoelectric effect, the phase difference between the two arms is exactly half a cycle, and the output optical signal is zero. When wavelength tuning is performed, the voltage on one of the waveguides of the MZM of the original channel changes, and the phase difference between the two arms becomes half a cycle, while the voltage on one of the waveguides of the MZM of the desired channel changes, and the phase difference between the two arms becomes zero, completing the wavelength tuning.

[0025] The wavelength switching of traditional tunable lasers requires milliseconds, and even the wavelength switching of the current advanced dot matrix tunable lasers requires nanoseconds. Since the modulation rate of the Mach-Zehnder modulator can reach hundreds of GHz, the switching speed of the ultrafast tunable light source described in this patent can reach sub-nanoseconds. This wavelength switching mechanism enables tunable lasers to quickly switch between different wavelengths to meet diverse application requirements: In optical communication networks, the wavelength switching speed of tunable lasers directly affects the flexibility of the network. With the development of the next generation of intelligent networks, the requirements for the wavelength switching speed of tunable lasers are getting higher and higher. In the field of phased array radar, faster wavelength switching speed means faster adjustment of the wavelength of the laser, which can achieve wide bandwidth and large angle scanning of the radar beam, thereby improving the detection performance and flexibility of the radar, and fast tunable lasers can provide stable and continuous optical signal output, thereby improving the reliability and stability of the radar system. In addition, in the field of optical switching, fast tunable lasers can provide multiple optical signal outputs of different wavelengths, thereby supporting more optical channels and higher network capacity.

[0026] Examples In order to better demonstrate the functional characteristics of the ultrafast tunable laser emission light source, this patent embodiment takes an eight-way light wave output light source as an example. The ultrafast tunable laser emission light source system embodiment includes an eight-channel laser array, an eight-array Mach-Zehnder modulator, and seven 2×1 couplers. The eight-channel array laser chip is as follows: Figure 1 As shown in the figure, the chip is mounted on the carrier film circuit, and then the TEC temperature control module is added to achieve the precise output of eight wavelengths of light. This structure can realize the eight ports of the eight-array laser to input multiple wavelengths of light at the same time. The eight-array Mach-Zehnder modulator is used as a switch to control the on and off of each wavelength, and the output light is combined in the coupler. Figure 2 The chip schematic is shown in Figure 3 shown.

[0027] Step 1: The starting wavelength of the eight-channel array laser chip is the C60 channel of the DWDM standard wavelength: 1529.55nm, corresponding to a frequency of 196THz, and a channel spacing of 100GHz. The corresponding grating period is calculated according to the laser wavelength, and the laser array is prepared using epitaxial growth technology. Crystals are grown layer by layer on the substrate to form high-quality epitaxial layers, including a lower confinement layer, an active area, and an upper confinement layer, to ultimately form the structure of the laser. After the preparation of the laser chip is completed, a suitable carrier is designed for the chip to be mounted, and the chip electrodes and the carrier electrodes are connected by gold wire bonding to form a COC (chip on carrier). The COC is mounted on the TEC temperature control module to ensure the consistency of the laser operating temperature, thereby achieving precise and stable output. The laser chip is tested to obtain a spectrum such as Figure 5 The schematic diagram of the eight-channel array laser chip structure is shown in Figure 1 shown.

[0028] Step 2: Design a silicon-based array Mach-Zehnder modulator based on the waveguide spacing of the laser. The waveguide and modulator structures are constructed through precise etching and deposition processes, thus completing the manufacture of the entire array Mach-Zehnder modulator. Finally, to ensure that all performance indicators of the modulator meet the requirements, comprehensive testing and performance optimization are carried out. Formula 3 and Figure 4 The output characteristic equation of the Mach-Zehnder modulator and its corresponding output characteristic curve are shown respectively.

[0029] Step three, use photon wire bonding to heterogeneously integrate different materials. Specifically, according to the optical field mode field diameter (MFD) of the laser and modulator, the shape of the photon wire bonding between the laser and the modulator is carefully calculated and designed to ensure mode matching and gradually convert the size of the optical field. Then control the high-energy pulse beam to undergo multi-photon polymerization in the photoresist, identify the area based on machine vision technology, and accurately control the trajectory and shape of the beam to form a photon wire bonding that meets the design requirements, complete heterogeneous integration, and lay the foundation for the construction of optoelectronic devices and integrated optical systems.

[0030] Step 4: Test the prepared eight-channel ultrafast tunable laser emission source. By collecting and analyzing a large amount of data, the spectrum of the laser emission module when it is lit at the same time is finally obtained. The eight ports output eight light waves with a starting wavelength of 1529.55nm and a spacing of 100GHz. The wavelength output is accurate and stable. The specific wavelength switching process of the embodiment is as follows: Figure 5As shown, in the initial state, the array lasers LD1 to LD8 are all in the light-on state, MZM1 in the array Mach-Zehnder modulator is in the initial state, no external voltage is applied to the waveguide, the phase difference between the two arms is zero, and the amplitude of the output optical signal remains constant; while one of the waveguides from MZM2 to MZM8 is acted upon by an external voltage, due to the photoelectric effect, the phase difference between the two arms is exactly half a cycle, and the output optical signal is zero. After coupling, the eight-channel ultrafast tunable laser emission light source emits a wavelength of If the system no longer needs wavelength of light, which in turn requires When wavelength tuning is performed, the voltage on one waveguide of MZM1 changes, and the phase difference between the two arms becomes half a cycle, while the voltage on one waveguide of MZM2 changes, and the phase difference between the two arms becomes zero. After coupling, the eight-channel ultrafast tunable laser emission light source emits a wavelength of of light to complete wavelength tuning. Figure 6 A tuning schematic diagram of the ultrafast tunable laser emission source is given. The eight-channel ultrafast tunable laser emission source can complete wavelength tuning in sub-nanosecond time, which is several orders of magnitude faster than traditional tunable lasers. Under the same structure, if a higher-speed Mach-Zehnder modulator is used, a faster switching speed can be achieved, thereby realizing wide-bandwidth and large-angle scanning of radar beams in the field of phased array radars, thereby improving the detection performance and flexibility of radars; in the field of optical switching, by quickly adjusting the wavelength of the laser, dynamic routing of optical signals in optical networks can be achieved, thereby improving the flexibility and scalability of the network.

[0031] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. An ultrafast tunable precision laser emission source, characterized in that: The ultrafast tunable precision laser emission light source includes an N-channel array laser chip based on the reconstruction equivalent chirp technology, an N-channel array Mach-Zehnder modulator and a coupler; The N output ends of the array laser chip are connected to the N input ends of the array Mach-Zehnder modulator correspondingly, and the N output ends of the array Mach-Zehnder modulator are connected to the coupler; Each output end of the array laser chip outputs laser light of a DWDM standard wavelength, and each laser beam enters the corresponding input end of the array Mach-Zehnder modulator. The array Mach-Zehnder modulator acts as a laser switch to modulate each laser beam, and the modulated laser beams are combined through a coupler.

2. The ultrafast tunable precision laser emission source according to claim 1, characterized in that: The array Mach-Zehnder modulator adjusts the radio frequency signal in real time according to the wavelength of the input laser to control the input-output ratio, so that the laser of the set channel is output to the coupler.

3. The ultrafast tunable precision laser emission source according to claim 1, characterized in that: The multi-channel array laser chip calculates the period of the grating according to the following formula: ； Refractive index modulation amplitude of the grating part The refractive index modulation amplitude of the seed grating and the Fourier coefficients of the m-order sub-grating The relationship is as follows: In the formula is the output wavelength, is the equivalent refractive index in the waveguide, is the grating period, z is the position in the laser resonant cavity direction, is the variation of the sampling period.

4. The ultrafast tunable precision laser emission source according to claim 1, characterized in that: The single-channel inference formula of the array Mach-Zehnder modulator satisfies the following conditions: Assume the input light field at time t and drive voltage They are: Additional phase caused by DC bias voltage for: Output light field after DC bias voltage for: , is the power distribution ratio of the two Y splitters. Under ideal conditions, , then the output power is: in is the amplitude of the input light field, and is the frequency and initial phase of light, V DC is the DC bias voltage, V RF is the amplitude of the driving voltage, and are the driving voltage frequency and initial phase respectively, The wavelength is The light in the phase modulator generates a voltage with an additional phase of π. is the input optical power of the Mach-Zehnder modulator; by controlling the DC bias of the Mach-Zehnder modulator The initial working point is set, and the RF signal V(t) is controlled to adjust the input-output ratio of the array Mach-Zehnder modulator, and the output of each channel is controlled to act as a switch.

5. The ultrafast tunable precision laser emission source according to claim 1, characterized in that: Photonic wire bonding technology is used for heterogeneous integration of different materials, and photonic wires are used to transmit optical signals.

6. The ultrafast tunable precision laser emission source according to claim 5, characterized in that: Photonic leads were prepared by two-photon exposure technique.

7. The ultrafast tunable precision laser emission source according to claim 1, characterized in that: The array Mach-Zehnder modulator is a silicon-based Mach-Zehnder modulator.

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