Compact electric pump coherent broadband mid-infrared mixed chalcogenide glass-silicon substrate integrated light source system

Abstract

The invention relates to the technical field of optoelectronic devices, and discloses a compact electric pumping coherent broadband intermediate infrared chalcogenide glass-silicon-based hybrid integrated light source system. The system comprises a pumping femtosecond laser module on a silicon substrate and an optical fiber spread spectrum compression module. The on-chip module generates femtosecond pulses under the pumping of an electric pump; the optical fiber module sequentially comprises a chalcogenide photonic crystal fiber and an anomalous dispersion compensator. The output end of the on-chip module is optically coupled with the input end of the chalcogenide fiber, and the output end of the chalcogenide fiber is connected to the anomalous dispersion compensator. The spectrum of the femtosecond pulse is broadened through the nonlinear effect in the chalcogenide fiber, then the pulse is compressed by the anomalous dispersion compensator, and finally broadband intermediate infrared coherent light is output. According to the system, low-power-consumption, wide-spectrum and high-coherence mid-infrared laser output is realized by a compact electric pumping framework through hybrid integration and dispersion nonlinear collaborative management.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optoelectronic devices, and particularly relates to a compact electrically pumped coherent broadband mid-infrared hybrid chalcogenide glass-silicon-based integrated light source system. BACKGROUND

[0002] The mid-infrared waveband (usually referring to a wavelength of 2.5-20 μm) has irreplaceable application value in the fields of molecular spectrum detection, environmental gas sensing, medical diagnosis and industrial process monitoring due to its containing a large number of unique fingerprint absorption spectral lines of gas molecules. Realizing a mid-infrared light source with high performance, low cost and miniaturization is the key to promoting the popularization of the above-mentioned applications.

[0003] At present, the technical route for generating mid-infrared coherent light mainly relies on an optical parametric oscillator (OPO) and a quantum cascade laser (QCL). The optical parametric oscillator (OPO) can generate broadband mid-infrared output, but its system usually relies on a bulky optical resonant cavity with a size of meters and a high-power pump source with a power of kilowatts, and needs a precise temperature control and mechanical tuning system. This makes the OPO system have high power consumption, poor stability and difficulty in mobilization, and cannot meet the application requirements of portable or embedded devices. The quantum cascade laser (QCL) has the potential for chip-level integration, but its output spectral range is usually narrow (generally less than 100 nm), and most working modes need to rely on a cryogenic cooling device to maintain performance, which greatly limits its applicability in many normal temperature and wide spectrum detection scenarios.

[0004] With the development of silicon photonics technology, using mature complementary metal oxide semiconductor (CMOS) process to manufacture integrated optoelectronic devices is considered as an ideal path to realize a miniaturized mid-infrared light source. However, the silicon material itself has significant two-photon absorption effect and high waveguide transmission loss (usually more than 3 dB / cm at a wavelength of 2 μm and above) in the mid-infrared waveband, resulting in that the working wavelength of the silicon-based laser is mostly limited to the near-infrared waveband of 1.3-1.6 μm, and it is difficult to directly and effectively extend to the mid-infrared region. On the other hand, chalcogenide glass (such as Ge-As-Se system) optical fiber is an ideal nonlinear medium for generating supercontinuum spectrum due to its super-high nonlinear coefficient (γ>50 W -1 m -1 ) and extremely low transmission loss (<0.5 dB / m@3-5 μm) in the mid-infrared waveband. However, the existing supercontinuum spectrum generation scheme based on chalcogenide optical fiber seriously relies on an external large femtosecond pulse laser as a pump source, and the required peak power is usually more than 100 W. Such high power requirement makes the entire light source system incompatible with the chip-level integration target in terms of volume and power consumption.

[0005] In addition, even if the silicon-based laser and the chalcogenide optical fiber are mixed and integrated, there are two key technical bottlenecks: first, due to the significant mode field mismatch between the silicon-based waveguide and the chalcogenide optical fiber, the coupling loss between them is high (typically more than 3 dB), which seriously restricts the overall energy efficiency of the system; second, in the process of supercontinuum generation, the nonlinear effect and the dispersion characteristics are not effectively coordinated and regulated, so it is difficult to achieve wide spectral broadening while ensuring the coherence and stability of the output spectrum. SUMMARY

[0006] In view of the high coupling loss, the difficulty in performance regulation and the poor system compatibility of the existing mixed integration of the silicon-based laser and the chalcogenide optical fiber, the present application provides a compact electrically pumped coherent broadband mid-infrared mixed chalcogenide glass-silicon-based integrated light source system, which realizes low-power consumption, wide spectral coverage and high coherence of the mid-infrared laser output in a compact electrically pumped driving architecture through low-loss mixed integration of the femtosecond laser on the silicon substrate and the chalcogenide photonic crystal optical fiber and dispersion nonlinear coordinated regulation.

[0007] In order to achieve the above technical purpose, the present application specifically adopts the following technical solutions: In one aspect of the present application, a compact electrically pumped coherent broadband mid-infrared mixed chalcogenide glass-silicon-based integrated light source system is provided, which comprises a pumped femtosecond laser module on a silicon substrate and a fiber spectrum expansion and compression module. The pumped femtosecond laser module on the silicon substrate is configured to generate and output femtosecond laser pulses under electric pumping; the fiber spectrum expansion and compression module comprises a chalcogenide photonic crystal optical fiber and an anomalous dispersion compensator arranged in sequence; the output end of the pumped femtosecond laser module on the silicon substrate is optically coupled with the input end of the chalcogenide photonic crystal optical fiber, and the output end of the chalcogenide photonic crystal optical fiber is connected with the anomalous dispersion compensator. The femtosecond laser pulses are nonlinearly spectrally broadened in the chalcogenide photonic crystal optical fiber, and then are pulse-compressed by the anomalous dispersion compensator to output broadband mid-infrared coherent light.

[0008] In one embodiment, the pumped femtosecond laser module on the silicon substrate comprises a pump laser, a saturable absorber mirror, a first wavelength division multiplexer, a gain waveguide, an optical coupler, a distributed grating, a semiconductor optical amplifier, an isolator and a pulse compression waveguide. The output end of the pump laser is connected with the pump port of the first wavelength division multiplexer, the common end of the first wavelength division multiplexer is connected with the input end of the gain waveguide to form a gain unit of a laser resonant cavity, and the output end of the gain waveguide is connected with the common end of a second wavelength division multiplexer; the signal end of the second wavelength division multiplexer is connected to the saturable absorber mirror after passing through the optical coupler and the distributed grating in sequence, thereby together forming a linear Fabry-Perot resonant cavity. The optical coupler also serves as an output end of the laser pulse, and the output signal thereof sequentially passes through a semiconductor optical amplifier for power amplification, an isolator for ensuring unidirectional transmission of an optical path, and a pulse compression waveguide for dispersion management and pulse compression, and finally outputs a compressed femtosecond laser pulse.

[0009] In an embodiment, the fibered supercontinuum compression module comprises a first microlens, a chalcogenide photonic crystal fiber, a second microlens, a beam splitter, an anomalous dispersion compensator, and a collimating lens. An output end of the silicon-on-substrate pumped femtosecond laser module is optically coupled with an input end of the chalcogenide photonic crystal fiber through the first microlens, an output end of the chalcogenide photonic crystal fiber is connected with the beam splitter through the second microlens, and a transmission light path of the beam splitter sequentially provides the anomalous dispersion compensator and the collimating lens.

[0010] In an embodiment, the gain waveguide adopts a hetero-integrated structure of a III-V semiconductor material and a silicon-on-insulator waveguide, wherein the III-V semiconductor material is an InGaAs / GaAsSb quantum well bonded on the surface of the silicon-on-insulator waveguide through a transfer printing technology to form a monolithic integrated resonant cavity.

[0011] In an embodiment, the resonant cavity is composed of a distributed feedback Bragg grating and a ring cavity structure.

[0012] In an embodiment, the cross-sectional size of the pulse compression waveguide is optimized to achieve anomalous dispersion to suppress nonlinear loss.

[0013] In an embodiment, the chalcogenide photonic crystal fiber adopts a hexagonal arrangement microstructure of a chalcogenide glass material, and by adjusting the core and aperture ratio, the zero dispersion point of the fiber is located in the 2.3-2.5 μm waveband, and the fiber has a super-high nonlinear coefficient and a low transmission loss.

[0014] In an embodiment, the chalcogenide photonic crystal fiber realizes spectral broadening under the condition that the input peak power is lower than 50 W through the cooperative action of the normal dispersion broadening mode and the soliton self-frequency shift mechanism.

[0015] In an embodiment, the waveguide of the silicon-on-substrate pumped femtosecond laser module and the end face of the chalcogenide photonic crystal fiber are coupled through a tapered structure, the tapered structure is formed through an etching process, the mode field diameter is gradually expanded to realize mode field matching, and the coupling loss is lower than 1 dB.

[0016] In one embodiment, the pulse compression waveguide adopts a segmented dispersion design, including a front normal dispersion region for pulse compression and a rear abnormal dispersion region for soliton shaping, which cooperates with the flattened dispersion curve of the chalcogenide photonic crystal fiber to realize stable transmission of dispersion-managed soliton pulses.

[0017] In one embodiment, the abnormal dispersion compensator is made of quartz or calcium fluoride material, in a block cuboid structure or a wedge-shaped triangular pair structure, and the wedge-shaped triangular pair is connected with a piezoelectric motor to realize adjustable dispersion compensation.

[0018] In one embodiment, the optical splitter guides more than 90% of the power of the transmitted light path to the abnormal dispersion compensator, and reflects less than 10% of the power to a monitoring unit for working state monitoring and power adjustment.

[0019] In one embodiment, the monitoring unit is a power meter or an integrated photodiode.

[0020] In one embodiment, the system outputs a pulse width less than 20 fs, a spectral coverage of 2.5-5.0 μm band, and maintains high coherence and low noise during supercontinuum spectrum generation.

[0021] The beneficial effects of the present application are: 1) Miniaturization and system integration are achieved: the present application integrates an electrically pumped silicon-based mode-locked laser with a chalcogenide photonic crystal fiber, discards the bulky and high-power external pump laser in the traditional scheme, and constructs a complete on-chip light source system. The system is compact, laying a solid foundation for realizing portable and chip-level mid-infrared optoelectronic applications.

[0022] 2) The system power consumption and working threshold are significantly reduced: through the dispersion engineering of the silicon waveguide and the synergistic optimization of the microstructure of the chalcogenide fiber, the pump power threshold for supercontinuum generation is successfully reduced to below 50 W, which can match the output capacity of the chip-level light source, and solves the core contradiction between high-power pumping demand and integration target.

[0023] 3) High-performance spectral output is ensured: the synergistic effect of dispersion-managed soliton pulses and strong nonlinear effects of chalcogenide materials realizes high-coherence and wide-spectrum supercontinuum output in the 2.5-5.0 μm band. At the same time, through the integrated abnormal dispersion compensator, the output pulse can be compressed to below 20 fs, and high-quality few-cycle pulses are obtained.

[0024] 4) Improved energy efficiency and stability of the system: By innovative design of the tapered waveguide end face, the problem of mode field mismatch between silicon-based devices and chalcogenide optical fiber is effectively solved, and the coupling loss is reduced to below 1 dB, which significantly improves the energy transmission efficiency of the system. The design of the full polarization maintaining optical fiber and the linear chirp pulse regulation technology further enhances the robustness and long-term working stability of the system in harsh environments. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a schematic diagram of the system of the embodiment of the present application; Figure 2 is a schematic diagram of the structure of the silicon-based pumped femtosecond laser module of the embodiment of the present application; Figure 3 is a schematic diagram of the structure of the chalcogenide photonic crystal fiber spectrum expansion module of the embodiment of the present application; Figure 4 is a schematic diagram of the geometry of the dispersion adjustment optical fiber of the embodiment of the present application; Figure 5 is the mid-infrared output spectrum of the embodiment of the present application; Figure 6 is the time-domain distribution of the output pulse of the chalcogenide optical fiber of the embodiment of the present application; In the figure: 201, saturable absorber mirror, 202, pump laser, 203, first wavelength division multiplexer, 204, gain waveguide, 205, second wavelength division multiplexer, 206, optical coupler, 207, distributed grating, 208, isolator, 209, semiconductor optical amplifier, 210, pulse compression waveguide; 301, first microlens, 302, chalcogenide photonic crystal fiber, 303, second microlens, 304, optical splitter, 305, anomalous dispersion compensator, 306, collimating lens. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described in detail below with reference to specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0027] In one specific embodiment of the present application, with reference to Figure 1As shown, a compact electrically pumped coherent broadband mid-infrared chalcogenide glass-silicon-based integrated light source system is provided, which integrates the functions of electrically pumped femtosecond pulse generation, nonlinear spectral broadening and pulse compression by hybrid integration of a silicon-based photonic chip and a chalcogenide glass fiber, and finally realizes high-efficiency and high-coherence broadband mid-infrared laser output. The system comprises a silicon-based on-chip pumped femtosecond laser module and a fiber spectral broadening and compression module.

[0028] The silicon-based on-chip pumped femtosecond laser module is based on the principle of electrically pumped mode-locked laser, and forms and maintains ultrashort pulse oscillation in the laser resonant cavity through a mode-locked element. The time-domain and frequency-domain characteristics of the pulse are regulated by using the dispersion management (such as introducing a distributed grating) of the silicon-based waveguide, to generate initial femtosecond-level (for example, hundreds of femtosecond-level) laser pulses. Specifically, the electric pumping energy is absorbed by the gain medium and converted into laser energy. Under the mode-locked mechanism, ultrashort optical pulses are formed in the cavity. The average power of the pulses is then amplified to hundreds of milliwatts from milliwatts, so as to obtain high peak power and provide sufficient driving energy for subsequent nonlinear processes.

[0029] The fiber spectral broadening and compression module comprises a chalcogenide photonic crystal fiber and an anomalous dispersion compensator arranged in sequence. The output end of the silicon-based on-chip pumped femtosecond laser module is connected to the input end of the chalcogenide photonic crystal fiber in an optical coupling manner, and the output end of the chalcogenide photonic crystal fiber is optically connected to the anomalous dispersion compensator. After the femtosecond laser pulses are nonlinearly spectrally broadened in the chalcogenide photonic crystal fiber, pulse compression is performed by the anomalous dispersion compensator, and finally broadband mid-infrared coherent light is output.

[0030] Specifically, the high-peak-power femtosecond pulses output from the silicon-based on-chip pumped femtosecond laser module are injected into the chalcogenide photonic crystal fiber through low-loss coupling technology. The fiber sets its zero dispersion point at the 2.3-2.5 μm wavelength band near the pump wavelength by regulating the arrangement and size of the air holes, so that the pulse realizes significant spectral broadening by means of nonlinear effects such as self-phase modulation during transmission, and cooperates with the normal dispersion broadening mechanism or soliton dynamics to efficiently expand the spectrum from near-infrared (about 2 μm) to the 2.5-5.0 μm mid-infrared band or even a wider band, while maintaining good spectral coherence during the entire process.

[0031] The abnormal dispersion compensator is based on dispersion compensation principle, and is used for time domain compression of a pulse carrying a large amount of normal dispersion (linear chirp) after nonlinear broadening of the chalcogenide photonic crystal fiber; the chirp pulse is incident into an optical element composed of a mid-infrared abnormal dispersion material after collimation, and the chirp accumulated in the fiber is effectively offset by causing different frequency components to produce corresponding delays, so that the pulse width is compressed to a femtosecond or even a sub-20 fs ultra-short time domain scale. Finally, the system outputs coherent light with the characteristics of a wide spectrum (covering the mid-infrared band) and an ultra-short pulse (high peak power).

[0032] The system replaces a traditional bulky femtosecond laser with an electrically pumped chip-on-silicon, and is mixed and integrated with a chalcogenide fiber module, thereby greatly reducing the volume and complexity of the system, and laying a foundation for developing a desktop or portable mid-infrared light source device. Meanwhile, by using the super-high nonlinear effect of the chalcogenide glass fiber, high-efficiency spectral broadening can be realized at a relatively low pump power, and the molecular fingerprint spectrum region is covered. By dispersion coordination design and normal dispersion broadening mechanism, nonlinear noise is effectively suppressed, and high coherence and low intensity noise of the output supercontinuum spectrum are ensured.

[0033] In some embodiments, referring to Figure 1 and Figure 2 The silicon chip-on-pump femtosecond laser module comprises a pump laser 202, a saturable absorber mirror 201, a first wavelength division multiplexer (WDM1) 203, a gain waveguide 204, a second wavelength division multiplexer 205, an optical coupler 206, a distributed Bragg grating (DBR) 207, a semiconductor optical amplifier (SOA) 209, an isolator (ISO) 208, and a pulse compression waveguide (CPW) 210.

[0034] An output end of the pump laser 202 is connected with a pump port of the first wavelength division multiplexer 203. A common end of the first wavelength division multiplexer 203 is connected with an input end of the gain waveguide 204, and forms a gain unit of a laser resonant cavity. An output end of the gain waveguide 204 is connected with a common end of the second wavelength division multiplexer (WDM2) 205. A signal end of the second wavelength division multiplexer 205 is connected to the saturable absorber mirror 201 in sequence through the optical coupler 206 and the distributed Bragg grating 207. The saturable absorber mirror 201, the gain waveguide 204, the second wavelength division multiplexer 205, the optical coupler 206 and the distributed Bragg grating 207 jointly form a linear Fabry-Perot (F-P) resonant cavity.

[0035] Meanwhile, the optical coupler 206 also serves as the output end of the laser pulse, and the output signal thereof sequentially passes through the semiconductor optical amplifier 209 for power amplification, the isolator 208 for ensuring unidirectional transmission of the optical path, and the pulse compression waveguide 210 for dispersion management and pulse compression, and finally outputs the compressed femtosecond laser pulse.

[0036] The working process of the laser module follows the principle of mode-locked laser generation of a linear F-P resonant cavity, and the specific steps are as follows: Pumping and gain generation: a pump laser 202 (for example, a pump laser diode) driven by electric pumping generates pump light. The pump light is injected through the pump port of the first wavelength division multiplexer 203, is output from the common port thereof, and enters the gain waveguide 204.

[0037] Resonant cavity circulation and mode locking start: the stimulated radiation light oscillates back and forth between the high-reflection end composed of the saturable absorber mirror 201 and the distributed grating 207. The optical path is as follows: the light output from the gain waveguide 204 enters the common port of the second wavelength division multiplexer 205, is output from the signal port thereof, passes through the optical coupler 206, and is subjected to dispersion compensation and wavelength selection by the distributed grating 207, and finally reaches the saturable absorber mirror 201. The saturable absorber mirror 201 has a saturable absorption characteristic, and when the cavity light power is low, the absorption loss is high. With the circulation of light in the cavity, the energy is continuously accumulated, and when the total energy makes the saturable absorber reach the saturation state, the absorption loss sharply decreases, and the total loss in the cavity instantaneously decreases, thereby meeting the threshold condition for laser emission. This process promotes the laser to work in a mode-locked manner, and releases a series of ultrashort pulses.

[0038] Pulse extraction and amplification: when the formed mode-locked pulse reaches the optical coupler 206 each time, a small part (for example, not more than 10%) of the energy thereof is coupled out as a laser pulse. Most of the energy continues to circulate in the cavity to maintain the mode-locked operation. The coupled-out pulse first enters the semiconductor optical amplifier (SOA) 209 for power amplification, significantly increasing the average power from the order of milliwatt to the order of hundred milliwatt, thereby obtaining high peak power.

[0039] Isolation and pulse compression: the amplified pulse passes through the isolator 208 to ensure unidirectional transmission of the optical signal and prevent the reflected light from the subsequent components from returning to the laser cavity to destroy the stability thereof. Subsequently, the pulse enters the pulse compression waveguide 210. The pulse compression waveguide 210 is usually composed of a medium with abnormal dispersion characteristics, and is used for compensating and compressing the linear chirp generated after passing through the normally dispersive waveguide in the cavity. Through precise dispersion management, the pulse width is compressed to the order of hundred femtoseconds, and finally a femtosecond laser pulse with high quality and high peak power is output, which provides an ideal pump source for the subsequent fiber spectrum expansion compression module.

[0040] In certain embodiments, with reference to Figure 1 and Figure 3 As shown in FIG. 3, the fibered supercontinuum compression module includes the following elements arranged in sequence: a first microlens 301, a chalcogenide photonic crystal fiber 302, a second microlens 303, a beam splitter 304, an anomalous dispersion compensator 305, and a collimating lens 306.

[0041] The optical connection between each element is strictly constructed in the order of light transmission. The femtosecond laser pulses generated at the final output end of the silicon-on-chip pumped femtosecond laser module (i.e., the output end of the pulse compression waveguide 210) are first collimated and focused by the first microlens 301. The first microlens 301 efficiently couples the light beam emitted from the silicon-based waveguide into the input end of the chalcogenide photonic crystal fiber 302, thereby solving the problem of high coupling loss caused by the mismatch of the mode field size between the silicon-based waveguide and the chalcogenide fiber. The input end of the chalcogenide photonic crystal fiber 302 receives the femtosecond pulses from the first microlens 301 through optical splicing, and the output end is connected to the second microlens 303. The emitted light after being expanded by the chalcogenide photonic crystal fiber 302 is collimated by the second microlens 303 to form a parallel light beam, which is then incident on the beam splitter 304 (e.g., a partial mirror or a grating beam splitter). On the transmission path of the beam splitter 304, the anomalous dispersion compensator 305 and the collimating lens 306 are arranged in sequence. Specifically, most of the light energy transmitted by the beam splitter 304 enters the anomalous dispersion compensator 305, and the compressed broadband mid-infrared coherent light is finally output by the collimating lens 306.

[0042] Specifically, the spectral broadening and pulse compression process of the fibered supercontinuum compression module is as follows: High peak power pulse injection: the compressed high peak power femtosecond laser pulses output from the silicon-on-chip laser module are efficiently focused and injected into the core of the chalcogenide photonic crystal fiber 302 by the first microlens 301.

[0043] Nonlinear spectral broadening: when the pulse is transmitted in the chalcogenide photonic crystal fiber 302, strong nonlinear optical effects occur due to the extremely high nonlinear coefficient inherent in the chalcogenide glass material and the specific dispersion characteristics achieved through microstructure design. These effects mainly include self-phase modulation (SPM), soliton self-frequency shift (SSFS), and waveform breaking, etc. The synergistic effect of these effects leads to a significant broadening of the pulse spectrum, covering a mid-infrared wavelength band of 2.5 μm to 5.0 μm or even wider. In this process, the normal dispersion characteristics of the fiber help to maintain the coherence of the broadened spectrum.

[0044] Beam collimation and power monitoring: After the broadened pulse light is output from the chalcogenide photonic crystal fiber 302, it is collimated by the second microlens 303 into a parallel light beam for subsequent processing. After the parallel light beam is incident on the beam splitter 304, it is divided into two paths: the transmission light path, which carries more than 90% of the optical power, is the main signal light path, which continues to be transmitted to subsequent components for processing and output; the reflection light path, which reflects less than 10% of the optical power, can be guided to a power meter or an integrated photodiode (not fully shown in the figure), which is used to monitor the system output power and working state in real time, and to realize closed-loop control and system stability.

[0045] Dispersion compensation and pulse compression: The main light signal transmitted by the beam splitter 304 enters the anomalous dispersion compensator 305. After passing through the normal dispersion transmission and nonlinear broadening of the chalcogenide fiber, the pulse has been broadened in the time domain and has a chirp. The anomalous dispersion compensator 305 is made of a material with anomalous dispersion characteristics, such as quartz, calcium fluoride crystal, etc., which introduces a group velocity dispersion opposite to the inherent chirp of the pulse, thereby re-compressing the pulse in the time domain. This process can compress the pulse width from the picosecond level to below 20 femtoseconds, close to the Fourier transform limit, significantly improving the peak power.

[0046] Final collimation output: The compressed ultrashort pulse finally passes through the collimating lens group 306. The lens group is used to eliminate chromatic aberration and optimize the size and divergence angle of the output spot to adapt to different application scenarios (such as coupling into a spectrometer or transmitting to a sample to be tested). Finally, the system outputs a stable mid-infrared laser with a wide spectral coverage, high coherence, and ultrashort pulse width.

[0047] In some embodiments, in the femtosecond laser module pumped on the silicon substrate, the gain waveguide 204 adopts a hetero-integrated structure of III-V semiconductor material and silicon-on-insulator (SOI) waveguide.

[0048] The III-V semiconductor material is an InGaAs / GaAsSb quantum well, which serves as an active gain medium responsible for generating optical amplification under electrical pumping. The emission wavelength of this material system can effectively cover the 2.0 μm to 2.3 μm band, perfectly matching the pump wavelength required for subsequent nonlinear broadening of the chalcogenide fiber.

[0049] The silicon-on-insulator (SOI) is used as the basic waveguide platform, with the top silicon layer used to make low-loss optical waveguides and the buried oxide layer (BOX) providing the lower cladding layer to achieve effective confinement of the optical field and low transmission loss.

[0050] The integration of the III-V semiconductor material with the SOI waveguide is achieved by a transfer printing technique. Specifically, a high-quality InGaAs / GaAsSb quantum well gain structure is first epitaxially grown on a native substrate (such as an InP substrate), and then the prepared micro gain unit is peeled off from the native substrate and accurately bonded to the surface of a silicon chip on which a SOI waveguide circuit is previously prepared by a precise micro transfer technique. The optical gain characteristics of the III-V material and the low-loss, compact optical path control capability of the silicon waveguide are complementary to each other.

[0051] In some embodiments, the monolithic integrated resonant cavity can preferably be composed of a distributed feedback Bragg grating and a ring cavity structure.

[0052] The distributed feedback Bragg grating is made by periodically modulating the refractive index of the SOI waveguide (for example, by etching a periodic grating structure). It serves as a feedback element and a wavelength selector for the resonant cavity. Its working principle is that only light that satisfies the Bragg condition (i.e., the wavelength and the grating period satisfy a certain relationship) can be strongly reflected in the cavity and establish stable laser oscillation, thereby ensuring that the laser output is a single longitudinal mode or narrow linewidth laser to produce high-coherence femtosecond pulses.

[0053] The ring cavity structure is a closed waveguide loop in which light circulates and propagates. When combined with the gain unit and the distributed feedback Bragg grating, it can form a compact ring laser. Light repeatedly circulates through the gain medium in the ring cavity and is continuously amplified. The distributed feedback Bragg grating can be integrated into the straight waveguide portion of the ring cavity or serve as a coupling element to provide wavelength-selective feedback for the ring cavity.

[0054] The combination of the distributed feedback Bragg grating and the ring cavity structure together constitutes a high-performance on-chip resonant cavity. The ring cavity provides a long effective interaction length and a small mode volume, which is beneficial to reducing the laser threshold and improving the efficiency; while the distributed feedback Bragg grating ensures precise wavelength control and single-mode operation characteristics. This combined structure works in cooperation with the III-V gain unit bonded by the transfer printing technique to achieve stable, narrow linewidth electrically pumped laser output, providing a high-quality seed light source for subsequent mode locking and pulse compression.

[0055] In some embodiments, the pump laser 202, the saturable absorber mirror 201, the semiconductor optical amplifier 209 and the isolator 208 can be discrete or hybrid integrated components. Specifically, they can be fabricated on a silicon chip in a heterogeneous or hybrid integrated manner, e.g. the pump laser and the semiconductor optical amplifier can also be III-V / Si heterogeneous integrated devices. Or as miniaturized bulk optical components, they can be coupled to the waveguide facets on the SOI chip through high-precision mounting techniques (e.g. active alignment packaging).

[0056] In some embodiments, the distributed feedback grating and the ring cavity can be formed by direct etching on the SOI waveguide, together with the gain waveguide 204 part to form a complete, monolithic resonant cavity.

[0057] In some embodiments, the cross-sectional size of the pulse compression waveguide is optimized to achieve anomalous dispersion to suppress nonlinear loss.

[0058] wherein the cross-sectional size optimization refers to the precise design and fabrication of the width and height of the SOI (Silicon on Insulator) layer that constitutes the waveguide.

[0059] The dispersion property of a silicon waveguide is strongly dependent on its geometric size. By increasing the cross-sectional area of the waveguide (typically by increasing the width and / or height), the confinement strength of the optical field in the silicon core can be weakened, allowing more optical field energy to be distributed in the silica cladding. Since the material dispersion of silica is typically negative around 2 μm, the combined effect of this "waveguide dispersion" and "material dispersion" can make the waveguide exhibit overall anomalous dispersion at the target wavelength. Specifically, by simulating different combinations of width (e.g. from 400 nm to 800 nm) and height (e.g. from 220 nm to 500 nm) using electromagnetic simulation software (e.g. Lumerical MODE), the optimized size range that can provide the required amount of anomalous dispersion (e.g. a negative dispersion parameter D) around 2.1 μm wavelength can be determined.

[0060] Meanwhile, increasing the cross-sectional area of the waveguide can suppress nonlinear loss. For the same pulse energy, a larger cross-sectional area means that the spatial range of the optical field mode distribution (i.e., the effective mode field area) increases, which directly leads to two synergistic favorable effects: first, the optical power density (light intensity) decreases significantly, and the probability of nonlinear loss such as two-photon absorption (TPA) is proportional to the square of the light intensity, so the reduction of power density can directly and effectively weaken the TPA effect; second, the nonlinear coefficient γ of the waveguide is inversely proportional to the effective mode field area, and the expansion of the mode field area naturally reduces the γ value, thereby further suppressing the transmission loss and pulse waveform distortion caused by the nonlinear effects of self-phase modulation (SPM) and TPA. Therefore, by optimizing and increasing the cross-sectional size, the efficiency and high fidelity of the pulse compression process can be effectively guaranteed while achieving anomalous dispersion.

[0061] In some embodiments, the chalcogenide photonic crystal fiber uses chalcogenide glass (such as Ge-As-Se system) as the matrix material. Its cross section has a hexagonal arrangement of microstructures, that is, a solid core surrounded by a ring of air holes (or a defect core formed by missing an air hole), such as the several geometric structures shown in Figure 4

[0062] By precisely adjusting the ratio of the core diameter to the air hole diameter (i.e., the hole diameter ratio) and the hole spacing and other structural parameters, the dispersion characteristics of the optical fiber can be "tailored". In this embodiment, the optimization goal is to make the zero dispersion point (i.e., the wavelength at which the group velocity dispersion is zero) of the optical fiber in the 2.3 μm to 2.5 μm waveband, to ensure that the femtosecond pump pulses with a center wavelength of about 2.0-2.3 μm output from the silicon substrate pumped femtosecond laser are in the normal dispersion region when entering the optical fiber (i.e., the pump wavelength is less than the zero dispersion wavelength).

[0063] This microstructure design, in combination with the intrinsic properties of the material, brings two advantages: on the one hand, thanks to the extremely high nonlinear refractive index of chalcogenide glass and the ability of photonic crystal structure to confine the light field energy to a small core, the optical power density is significantly improved, so that the optical fiber as a whole exhibits an ultra-high nonlinear coefficient; on the other hand, the optimized preparation process ensures that the chalcogenide glass matrix still has extremely low transmission loss (typical value less than 0.5 dB / m) in the mid-infrared waveband of 3-5 μm. The former is the basis for achieving efficient nonlinear spectral broadening, and the latter ensures that the broadened wide spectrum signal can be transmitted with low loss, which together provides a key guarantee for realizing efficient and wideband mid-infrared light source output.

[0064] The chalcogenide photonic crystal fiber realizes effective spectral broadening under the condition of low input peak power (less than 50 W) through the synergistic effect of normal dispersion broadening mode and soliton self-frequency shift mechanism. The specific physical process is as follows:​ Normal dispersion broadening (ANDi) dominant: Since the pump pulse propagates in the normal dispersion regime of the fiber, the main nonlinear effect is self-phase modulation (SPM). SPM broadens the pulse spectrum symmetrically. More importantly, in the normal dispersion regime, the walk-off effect between different frequency components is weak, which helps to maintain the phase relationship between different spectral components during the broadening process, thus ensuring the generated supercontinuum spectrum has high coherence.

[0065] Soliton self-frequency shift mechanism assisted: Although the whole is in the normal dispersion regime, the long-wavelength part after broadening enters the anomalous dispersion regime of the fiber. In this region, the pulse can form a soliton and further shift its center wavelength to the mid-infrared (e.g. 3-5 μm) direction through the soliton self-frequency shift effect (SSFS, driven by Raman effect), further widening the spectral coverage.

[0066] Synergistic effect and low power operation: ANDi mode is responsible for generating a wide spectrum and maintaining coherence, while SSFS mechanism is responsible for effective energy transfer to the mid-infrared band. These two mechanisms work synergistically on the platform of a carefully designed dispersion curve, significantly reducing the requirement for peak power of the pump pulse. Compared with the traditional scheme which requires a peak power of more than 100 W, the present application optimizes the dispersion and nonlinearity to start an effective spectral broadening process under the input condition of a peak power of less than 50 W, thus matching the output capability of chip-level silicon-based lasers.

[0067] In some embodiments, a specially designed tapered coupling structure is used to achieve efficient optical power transmission between the output waveguide of the silicon-based on-chip pump femtosecond laser module and the input end of the chalcogenide photonic crystal fiber 302.

[0068] Specifically, the tapered structure is prepared by using an anisotropic or selective etching process (such as reactive ion etching) at the output end of the waveguide of the silicon-based chip. The tapered structure is an extension of the waveguide itself, and its lateral dimensions (such as width and / or height) gradually decrease along the direction of light transmission, forming a gradual transition zone. The mode field of light transmitted from a standard silicon waveguide (which usually has a smaller mode field diameter of sub-micron order) can be gradually expanded in the tapered zone, and the mode field diameter can be smoothly and adiabatically increased.

[0069] By accurately designing the length, taper angle and size of the final end face of the tapered zone, the expanded mode field distribution can be highly matched in spatial form and size with the mode field of the input end face of the chalcogenide photonic crystal fiber, and the scattering and radiation loss caused by low mode field overlap when light is coupled from the silicon chip into the chalcogenide fiber is minimized. Through the above tapered coupling structure, the present application achieves a coupling loss of less than 1 dB.

[0070] In certain embodiments, to achieve high-coherence supercontinuum generation, the temporal profile of the pulse before nonlinear broadening needs to be precisely controlled. To this end, the pulse compression waveguide 210 employs a segmented dispersion design. Specifically, the waveguide is divided into two regions in the direction of light propagation: a front normal dispersion region and a rear anomalous dispersion region.

[0071] The front normal dispersion region is designed to have normal dispersion (positive group velocity dispersion). The pulse output from the laser cavity, usually with slight negative chirp or near transform-limited, is compressed. Specifically, the normal dispersion causes linear chirp, which, when properly combined with the inherent frequency modulation characteristics of the pulse, narrows the pulse in the time domain and initially increases its peak power, preparing for subsequent nonlinear processes.

[0072] The rear anomalous dispersion region is immediately behind the front normal dispersion region. This region is designed to have anomalous dispersion (negative group velocity dispersion) for soliton formation. When the pulse compressed in the front region and with increased peak power enters this region, under the balanced action of anomalous dispersion and nonlinear effects (mainly self-phase modulation), the pulse evolves into an optical soliton, which remains stable in shape during transmission.

[0073] The segmented design produces a well-shaped, temporally stable dispersion-managed soliton pulse as a pump source. The dispersion-managed soliton pulse is then coupled into the chalcogenide photonic crystal fiber 302 for spectral broadening. The chalcogenide photonic crystal fiber has a flattened dispersion curve in the target wavelength range of 2.5-5.0 μm, i.e., the dispersion value changes little with wavelength, due to its microstructure design. The dispersion-managed soliton pulse produced by the pulse compression waveguide is coordinated with the flattened dispersion curve of the chalcogenide photonic crystal fiber. The flat dispersion characteristic effectively suppresses instability phenomena such as splitting, jitter, or too fast Raman soliton shift of the soliton during transmission due to dispersion fluctuations. This allows the soliton pulse to maintain stable transmission characteristics during nonlinear spectral broadening in the chalcogenide fiber, ensuring controllable phase relationships between spectral components during the broadening process, and ultimately enabling the system to output broadband, smooth, and coherent mid-infrared light.

[0074] In certain embodiments, the anomalous dispersion compensator 305 is a key element for pulse temporal compression in the fiber spectral expansion and compression module. The pulse, which has accumulated normal dispersion (positive chirp) after nonlinear broadening in the chalcogenide photonic crystal fiber, is introduced with an equal and opposite amount of anomalous dispersion (negative dispersion), thereby re-compressing the pulse width in the time domain and restoring its ultra-short pulse characteristics.

[0075] The anomalous dispersion compensator 305 is made of optical material with high mid-infrared light transmission and required anomalous dispersion characteristics, preferably quartz or calcium fluoride. Both materials have low absorption loss in the target mid-infrared waveband (e.g. 2.5-5.0 μm), and their material dispersion is anomalous in the waveband, which can provide effective negative dispersion.

[0076] The anomalous dispersion compensator 305 is a block cuboid structure or a wedge-shaped triangular pair structure. The block cuboid structure provides a fixed dispersion compensation amount, which is determined by the dispersion coefficient of the material and the precise thickness of the cuboid. This scheme is simple and stable, and is suitable for application scenarios with fixed compensation requirements. The wedge-shaped triangular pair structure is composed of two straight-angle wedge-shaped prisms (i.e. wedge-shaped triangular pairs) with the same material, shape and size, and the inclined surfaces of the two prisms are placed facing each other or away from each other. The wedge-shaped triangular pair is connected to a piezoelectric motor, which can accurately control the relative displacement of the two wedge-shaped prisms in the horizontal direction. The total effective material thickness of the light passing through the pair of prisms can be continuously and finely changed, so that the introduced anomalous dispersion amount can be dynamically and continuously adjusted, thereby realizing adjustable dispersion compensation.

[0077] In some embodiments, the beam splitter directs more than 90% of the power of the transmitted light path to the anomalous dispersion compensator, and reflects less than 10% of the power to a monitoring unit for working state monitoring and power adjustment. In one implementation, the monitoring unit is a power meter or an integrated photodiode.

[0078] The beam splitter 304 is a key element for realizing light path distribution and system monitoring in the fibered supercontinuum compression module. As shown in FIGS. Figure 1 and Figure 3 The beam splitter 304 is configured to split the received light beam according to a specific power ratio.

[0079] In the transmitted light path, more than 90% of the optical power is transmitted and directed to the subsequent anomalous dispersion compensator 305. Ensuring that most of the signal light energy after nonlinear spectral broadening can be effectively used for final pulse compression and output is the main channel to ensure the output power and efficiency of the system.

[0080] In the reflected light path, less than 10% of the optical power is reflected and directed to a monitoring unit. The monitoring unit is used for real-time monitoring of the system working state and power adjustment. By continuously monitoring the power level of this part of the reflected light, the stability of the final output power of the system can be indirectly reflected. These monitoring data can be used to build a feedback control loop, for example, when a power drop is detected, a feedback signal can be used to adjust the driving current of the pump laser 202 or the gain of the semiconductor optical amplifier 209 in the opposite direction, thereby realizing stable closed-loop control of the output power and ensuring long-term reliable operation of the system.

[0081] Specifically, the monitoring unit is preferably a power meter or an integrated photodiode. The power meter can be used to provide accurate power absolute value measurement, while the integrated photodiode can provide faster response speed, facilitating real-time and high-speed feedback control. The monitoring unit (such as the power meter position schematically pointed to in the middle) can be monolithically integrated on the chip, or can be installed as a discrete component beside the optical path. Figure 1

[0082] Embodiment The embodiment provides a compact electrically pumped coherent broadband mid-infrared hybrid chalcogenide glass-silicon-based integrated light source system, and specific components and working procedures thereof are as follows: 1. System composition Referring to Figure 1 , the system mainly comprises two modules: a pump femtosecond laser module on a silicon substrate and a fiber spectrum expansion and compression module.

[0083] The pump femtosecond laser module on the silicon substrate is used to generate femtosecond laser pulses with high peak power. The specific structure thereof is referred to Figure 2 , and comprises: Pump laser 202: a commercial semiconductor laser diode with a tail fiber, with a center wavelength of about 980 nm, and providing pump light through electrical driving.

[0084] Saturable absorber mirror 201: an element prepared based on semiconductor saturable absorber mirror technology, with a modulation depth of about 5% and a recovery time of several picoseconds.

[0085] First and second wavelength division multiplexers 203 and 205: fused-taper fiber wavelength division multiplexers, used for multiplexing and demultiplexing 980 nm pump light and about 2.1 μm signal light.

[0086] Gain waveguide 204: InGaAs / GaAsSb multi-quantum well is used as gain material, which is bonded to an SOI waveguide with a thickness of 340 nm through transfer printing technology, to form a monolithically integrated active waveguide with a length of about 5 mm.

[0087] Optical coupler 206: a directional coupler structure, with an output coupling ratio of 5%.

[0088] Distributed grating 207: a second-order Bragg grating etched on an SOI waveguide, providing wavelength selection feedback and dispersion compensation.

[0089] Semiconductor optical amplifier 209: an active amplification waveguide with a structure similar to that of the gain waveguide, with a length of about 10 mm.

[0090] ​Isolator 208: An on-line isolator with optical fiber is used to ensure unidirectional transmission of the optical path.

[0091] Pulse compression waveguide 210: An SOI waveguide with optimized cross-sectional size (width 650 nm, height 300 nm) is used, which is determined by simulation to provide the required abnormal dispersion (D ≈ -500 ps / (nm·km) near 2.1 μm wavelength, while the effective mode field area is increased to about 2 μm 2 to suppress nonlinear losses such as two-photon absorption. The waveguide uses a segmented design, with the front 2 mm being a normal dispersion region for pulse shaping, and the rear 3 mm being an abnormal dispersion region for soliton formation.

[0092] The fibered spectrum expansion and compression module is used to expand the spectrum of femtosecond pulses to the mid-infrared and compress the pulse width. Its specific structure is referred to Figure 3 , comprising: First micro-lens 301 and second micro-lens 303: Aspherical lenses made of calcium fluoride, numerical aperture NA=0.25, working waveband covering 2-5 μm.

[0093] Chalcogenide photonic crystal fiber 302: Ge 20 As 20 Se 60 glass as the matrix, prepared by extrusion drilling method. Its microstructure is hexagonal arrangement, hole spacing Λ=3.5 μm, hole diameter d=2.1 μm (hole diameter ratio d / Λ=0.6), core diameter about 4 μm. This design makes its zero dispersion point at about 2.4 μm wavelength, and the nonlinear coefficient γ is estimated to be 60 W -1 ·m -1 , transmission loss <0.4 dB / m in the 3-5 μm waveband. The fiber length is selected as 1.5 cm.

[0094] Splitter 304: A mid-infrared light splitting film coated on a calcium fluoride substrate is used, with transmittance set to 95% and reflectance 5%.

[0095] Abnormal dispersion compensator 305: In this embodiment, two right-angle wedge-shaped prisms made of calcium fluoride are used to form a wedge-shaped triangular pair structure. The wedge-shaped pair is connected with a piezoelectric motor (not shown in the figure), and by controlling the displacement of the piezoelectric motor through a program, the relative overlapping thickness of the two prisms can be continuously adjusted, so as to realize the precise adjustment of the dispersion amount, and the adjustment range corresponds to about ±100 fs 2 .

[0096] Collimating lens group 306: An afocal system composed of two calcium fluoride lenses, used for collimating and expanding the output beam.

[0097] Monitoring unit: A thermoelectric refrigeration type mercury cadmium telluride mid-infrared photodetector is used as an integrated photodiode to receive about 5% of the light power reflected by the optical splitter and feed the current signal back to the system main controller for real-time power monitoring.

[0098] The output end of the pump femtosecond laser module on the silicon substrate (i.e. the output end of the pulse compression waveguide 210) is connected to the input end of the chalcogenide photonic crystal fiber through a tapered coupling structure. The tapered structure is formed by local etching at the end of the SOI waveguide, with a length of about 100 μm and an end width of about 1.2 μm, so that the mode field diameter of the silicon waveguide gradually expands from about 1 μm to well match the mode field diameter of the input end of the chalcogenide photonic crystal fiber (about 4.5 μm), and the actual coupling loss is less than 0.8 dB.

[0099] 2. System workflow After the system is powered on, the pump laser 202 is driven to emit continuous pump light at 980 nm. The pump light enters the gain waveguide 204 through the first wavelength division multiplexer 203, excites the InGaAs / GaAsSb quantum well to produce particle inversion, and the gain waveband covers 2.0-2.3 μm.

[0100] In the linear F-P resonant cavity composed of the saturable absorber mirror 201, the gain waveguide 204, the second wavelength division multiplexer 205, the optical coupler 206 and the distributed grating 207, the mode-locked is realized by the fast saturable absorption effect of the saturable absorber mirror 201, and a pulse sequence with a repetition frequency of 100 MHz and a center wavelength of about 2.1 μm is generated.

[0101] The pulse sequence extracts 5% of the energy output through the optical coupler 206, and then enters the semiconductor optical amplifier 209 after filtering out the residual pump light through the second wavelength division multiplexer 205 for power amplification, so that the average power is increased from about 15 mW to 120 mW. The amplified pulse then enters the pulse compression waveguide 210, which uses its segmented dispersion characteristics for compression and soliton shaping, and finally outputs a femtosecond soliton pulse with a pulse width of about 60 fs and a peak power of about 45 W.

[0102] The high peak power pulse is coupled into the chalcogenide photonic crystal fiber 302 through the tapered coupling structure and the first microlens 301. When the pulse propagates in the fiber, it mainly undergoes spectral broadening through self-phase modulation and other nonlinear effects in the normal dispersion region (2.1 μm<0 dispersion point 2.4 μm) of the fiber while maintaining high coherence. At the same time, the long-wavelength components broadened to the anomalous dispersion region are further shifted to the mid-infrared through the soliton self-frequency shift mechanism. The two mechanisms work together to effectively broaden the spectrum in the 1.5 cm long fiber under a peak pump power of less than 50 W.

[0103] The broadened light is collimated by the second microlens 303, and then is divided into two paths by the beam splitter 304. About 5% of the light power in the reflection path is received by the photodiode for monitoring. About 95% of the light power in the transmission path enters the anomalous dispersion compensator 305 composed of a pair of calcium fluoride wedge prisms. By adjusting the relative position of the wedge pair, an appropriate amount of negative dispersion is introduced to compensate for the positive chirp accumulated in the broadening process, and the pulse is compressed to about 18 fs. The compressed pulse is finally output through the collimating lens group 306.

[0104] The spectral characteristics of the final output mid-infrared light of the embodiment are shown in Figure 5 The pulse time-domain characteristics are shown in Figure 6

[0105] Although the embodiments of the present application are described above with reference to the drawings, the present application is not limited to the specific embodiments and application fields described above, and the specific embodiments described above are merely illustrative and instructive, but not restrictive. Those skilled in the art can make many forms under the guidance of the present specification and without departing from the scope protected by the claims of the present application, which are all within the protection scope of the present application.​

Claims

1. A compact electrically pumped coherent broadband mid-infrared chalcogenide glass-silicon hybrid integrated light source system, characterized in that, The module comprises a silicon chip on-pumped femtosecond laser module and a fiber spectrum expansion compression module. The silicon chip on-pumped femtosecond laser module is configured to generate and output femtosecond laser pulses under electrical pumping; the fiber spectrum expansion compression module comprises a chalcogenide photonic crystal fiber and an abnormal dispersion compensator arranged in sequence; an output end of the silicon chip on-pumped femtosecond laser module is optically coupled with an input end of the chalcogenide photonic crystal fiber, and an output end of the chalcogenide photonic crystal fiber is connected with the abnormal dispersion compensator. The femtosecond laser pulses are nonlinearly spectrally broadened in the chalcogenide photonic crystal fiber, and then are pulse-compressed by the abnormal dispersion compensator to output broadband mid-infrared coherent light.

2. The hybrid chalcogenide glass-silicon-based integrated light source system of claim 1, wherein, The silicon chip on-pumped femtosecond laser module comprises a pump laser, a saturable absorber mirror, a first wavelength division multiplexer, a gain waveguide, an optical coupler, a distributed grating, a semiconductor optical amplifier, an isolator and a pulse compression waveguide. An output end of the pump laser is connected with a pump port of the first wavelength division multiplexer, a common end of the first wavelength division multiplexer is connected with an input end of the gain waveguide to form a gain unit of a laser resonant cavity, and an output end of the gain waveguide is connected with a common end of a second wavelength division multiplexer; a signal end of the second wavelength division multiplexer is connected to the saturable absorber mirror through the optical coupler and the distributed grating in sequence, thereby forming a linear Fabry-Perot resonant cavity. The optical coupler also serves as an output end of the laser pulses, and the output signal thereof is sequentially subjected to power amplification by the semiconductor optical amplifier, unidirectional transmission by the isolator, and dispersion management and pulse compression by the pulse compression waveguide, and finally outputs the compressed femtosecond laser pulses.

3. The hybrid chalcogenide glass-silicon-based integrated light source system of claim 1, wherein, The fiber spectrum expansion compression module comprises a first microlens, a chalcogenide photonic crystal fiber, a second microlens, a beam splitter, an abnormal dispersion compensator and a collimating lens. An output end of the silicon chip on-pumped femtosecond laser module is optically coupled with an input end of the chalcogenide photonic crystal fiber through the first microlens, an output end of the chalcogenide photonic crystal fiber is connected with the beam splitter through the second microlens, and a transmission light path of the beam splitter is sequentially provided with the abnormal dispersion compensator and the collimating lens.

4. The hybrid chalcogenide glass-silicon-based integrated light source system of claim 1, wherein, The gain waveguide adopts a hetero-integrated structure of III-V semiconductor material and silicon-on-insulator waveguide, wherein the III-V semiconductor material is InGaAs / GaAsSb quantum well, which is bonded on the surface of the silicon-on-insulator waveguide by transfer printing technology to form a monolithic integrated resonant cavity.

5. The hybrid chalcogenide glass-silicon-based integrated light source system of claim 1, wherein, The resonant cavity is composed of a distributed feedback Bragg grating and a ring cavity structure.

6. The hybrid chalcogenide glass-silicon-based integrated light source system of claim 1, wherein, The chalcogenide photonic crystal fiber adopts a hexagonal arrangement microstructure of chalcogenide glass material.

7. The hybrid chalcogenide glass-silicon-based integrated light source system of claim 1, wherein, The chalcogenide photonic crystal fiber realizes spectrum expansion through the cooperative action of normal dispersion broadening mode and soliton self-frequency shift mechanism under the condition that the input peak power is less than 50 W.

8. The hybrid chalcogenide glass-silicon-based integrated light source system of claim 1, wherein, The waveguide of the silicon chip on-pumped femtosecond laser module is coupled with the end face of the chalcogenide photonic crystal fiber through a tapered structure, and the tapered structure is formed by etching process to gradually expand the mode field diameter to realize mode field matching.

9. The hybrid chalcogenide glass-silicon-based integrated light source system of claim 1, wherein, The pulse compression waveguide adopts a segmented dispersion design, including a front normal dispersion region for pulse compression and a rear abnormal dispersion region for soliton shaping, which cooperates with the flattened dispersion curve of the chalcogenide photonic crystal fiber to realize stable transmission of the dispersion managed soliton pulse.

10. The hybrid chalcogenide glass-silicon-based integrated light source system of claim 1, wherein, The abnormal dispersion compensator is made of quartz or calcium fluoride material, and has a block cuboid structure or a wedge-shaped triangular pair structure, and the wedge-shaped triangular pair is connected with a piezoelectric motor to realize adjustable dispersion compensation.

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