External modulation laser chip integrated with Mach-Zehnder interferometric modulator
By introducing a dual output waveguide in the laser, the functions of continuous laser and spectrometer in the traditional Mach-Zendel interference modulator are integrated, and the problems of complex structure and high cost of external modulation laser chip are solved, and the structure is realized Simplification, cost reduction and performance improvement.
Patent Information
- Application Number
- CN202421857128.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-02
- Publication Date
- 2025-02-07
- Estimated Expiration
- 2034-08-02
AI Technical Summary
When existing external modulation laser chips realize high-speed optical signal modulation, the structure is complex and costly, and the design and manufacturing of traditional Mach-Zendel interference modulators are difficult.
The external modulation laser chip with integrated Mach-Zendel interference modulator is adopted to simplify the structure and manufacturing process by introducing a dual output waveguide in the laser.
The structure of traditional MZ modulated lasers is simplified, the chip size is reduced, the cost is reduced, the yield and output is improved, and a low-cost technical solution is provided for large-scale applications.
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Figure CN222441090U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a laser chip with an external modulator, in particular to an external modulated laser chip with an integrated Mach-Zehnder interferometer modulator. Background Art
[0002] The modulation of high-speed optical signals is the core of realizing large-capacity optical communications. Currently, there are two methods to realize high-speed modulation of optical signals: one is direct modulation, which directly drives the semiconductor laser with high-speed electrical signals to realize the output of modulated optical signals; the other is external modulation, which is to use the light waves continuously output by the semiconductor laser through an external modulator to realize the output of high-speed modulated optical signals.
[0003] Compared with direct modulation of lasers, external modulation requires a continuous laser and another modulator to achieve high-speed modulation of optical signals. Obviously, the structure of external modulation is more complex and the cost is higher than direct modulation. However, direct modulation is limited by the chirp effect of the laser itself and the dispersion of the optical fiber, and can generally only be used for short-distance high-speed optical signal transmission. For C-band 10Gbit / s optical signals, the general transmission distance is limited to about 10km. The chirp of the external modulation signal is much lower than that of direct modulation, so long-distance signal transmission can be achieved.
[0004] There are two main types of externally modulated lasers: one is the electro-absorption modulated laser (hereinafter referred to as EML) based on the effect of semiconductor material absorption changing with the external electric field; the other is the Mach-Zehnder modulated laser (hereinafter referred to as MZ modulated laser) based on the electro-optical effect of semiconductor materials. The former is widely used due to its smaller size, low modulation voltage and low manufacturing cost. However, EML can only be used for intensity modulation, while MZ modulated laser can be used for both intensity modulation and phase modulation. In addition, compared with EML, MZ modulated laser can control the chirp of the output optical signal, and the rate of the MZ modulator using traveling wave electrodes is not limited by the RC constant of the modulator, which can achieve a modulation rate higher than that of EML. Therefore, in coherent communications and higher-speed and longer-distance optical fiber transmission systems, MZ modulated lasers are the mainstream solution. However, since the size of MZ modulated lasers is much larger than EML, their high cost limits their large-scale application.
[0005] Existing integrated MZ modulated lasers such as Figure 1 As shown, the MZ modulated laser 1 includes a laser 2 providing continuous light output, a 3dB optical splitter 3a at the input end, two optical waveguides 4a and 4b for phase modulation, and a 3dB beam combiner 3b at the output end. Figure 1The electrodes for supplying current to the laser 2 and the electrodes for supplying modulated electrical signals connected to the phase modulated optical waveguides 4a and 4b are not shown. The optical splitter 3a at the input end and the beam combiner 3b at the output end of the MZ modulated laser 1 are 3dB directional couplers.
[0006] Of course, multi-mode interferometers (MMI) or other optical elements can also be used as beam splitters and combiners. Figure 2 The figure shows the use of 1X2 multimode interferometer (MMI) 3am as a 3dB splitter at the input end and 2X2 multimode interferometer (MMI) 3bm as a beam combiner at the output end. It is not difficult to see that the MZ modulated laser requires a light source, a splitter, a beam combiner, and two phase modulated optical waveguides. In actual use, a phase adjustment waveguide must be added. Therefore, the entire chip needs to be several millimeters long, which is much longer than the EML chip length of about 0.5 mm, so the chip cost increases significantly.
[0007] In addition, MZ modulated laser is based on phase modulation, so there are strict requirements on the phase and splitting ratio of the splitting and combining at the input and output ends. Otherwise, the final small light ratio of the modulator will not meet the requirements. For example, for Figure 1 The 3dB splitter based on directional coupler requires a splitting ratio of 50% / 50% and a phase difference of 90 degrees. These put forward extremely strict requirements on the chip manufacturing process, which ultimately affects the yield and cost of the chip.
[0008] Specifically, Figure 1 and Figure 2 In the conventional MZ modulated laser shown, the continuous laser 2 is composed of a straight waveguide, the rear end face of the waveguide is generally coated with a high reflective (HR) film, and the front port is connected to the beam splitter 3a or 3am. The beam splitter 3a or 3am divides the light from the continuous laser 2 into two light paths with the same intensity and a fixed phase difference, which enter the two phase waveguide arms 4a and 4b of the MZ modulator. In practice, due to manufacturing errors, it is difficult to achieve a perfect 50% / 50% intensity. For a 2X2 3dB beam splitter, the phase difference is 90 degrees (such as Figure 1 As shown); for 1X2 multimode interferometer, the phase difference is 0 (as shown Figure 2 Then the two beams pass through the second beam combiner 3b ( Figure 1 3dB directional coupler) or 3bm ( Figure 2 The phase of the two phase waveguides is modulated by an external electrical signal. The intensity modulation of the light output is achieved by phase modulation. Generally, the modulation phase difference between the two phase waveguides 4a and 4b varies between 0 and 180 degrees. The extinction ratio of the high and low levels of the output signal is determined by the splitting ratio and phase difference of the beam splitter 3a and the beam combiner 3b. Therefore, the MZ modulated laser has high requirements for chip manufacturing technology. Utility Model Content
[0009] The technical problem to be solved by the utility model is to provide an externally modulated laser chip with an integrated Mach-Zehnder interferometer modulator, which can simplify the design and manufacture of a traditional Mach-Zehnder interferometer modulator by utilizing the structure of the laser.
[0010] In order to solve the above technical problems, the technical solution of the externally modulated laser chip with integrated Mach-Zehnder interferometer modulator of the utility model is:
[0011] The invention comprises a laser, an optical beam combiner and two phase-modulated optical waveguides, wherein the laser has two waveguides to realize dual output in the same direction; the laser is powered by direct current; the laser is a continuous laser; the optical beam combiner has dual input ports; one end of the phase-modulated optical waveguide is respectively connected to the two waveguides of the laser, and the other end is respectively connected to the two input ends of the optical beam combiner; the phase-modulated optical waveguide is driven by an alternating current modulated electrical signal.
[0012] In another embodiment, the waveguide of the laser is a U-shaped structure.
[0013] In another embodiment, the two waveguides are connected at the other end of the dual outputs through a bent waveguide to form the waveguide of the laser.
[0014] In another embodiment, the two waveguides are connected at the other end of the dual outputs through two reflection surfaces and a waveguide in a perpendicular direction to form the waveguide of the laser.
[0015] In another embodiment, the waveguide of the laser is a V-shaped structure.
[0016] In another embodiment, the two waveguides are connected at the other end of the dual output via two bent waveguides.
[0017] In another embodiment, the two bent waveguides are placed in opposite directions at the other end face of the laser and meet at the end face of the laser.
[0018] In another embodiment, the end face of the laser is coated with a high reflective (HR) film.
[0019] In another embodiment, the waveguide of the laser is a Y-shaped structure.
[0020] In another embodiment, the two waveguides of the laser are connected to the same straight waveguide through a curved waveguide; the cavity facet end of the straight waveguide is coated with a high-reflection film.
[0021] In another embodiment, the optical combiner is a 1X2 multimode interferometer, a 2X2 multimode interferometer (MMI) or a 3dB directional coupler.
[0022] In another embodiment, the laser is a distributed feedback laser (DFB) with a grating structure;
[0023] In another embodiment, the laser is a distributed Bragg reflector laser (DBR);
[0024] In another embodiment, the laser is a wavelength tunable laser with a sampled grating structure.
[0025] In another embodiment, the two phase modulated optical waveguides have different lengths, and one of them has a bent waveguide.
[0026] In another embodiment, the phase modulated optical waveguide consists of two sections; one section is DC biased for phase adjustment, and the other section is connected to the modulated signal for signal modulation.
[0027] In another embodiment, a semiconductor optical amplifier is integrated after the optical combiner.
[0028] In another embodiment, the waveguide region of the laser comprises part or all of the grating structure.
[0029] In another embodiment, the grating is arranged symmetrically in the waveguide region of the laser.
[0030] In another embodiment, the waveguide width of the laser is about 1 to 3 microns.
[0031] The technical effects that can be achieved by the utility model are:
[0032] The utility model introduces a new continuous laser into the traditional MZ modulated laser. The laser has two output waveguides in the same direction, and the output lights have the same phase. Thus, the functions of the continuous laser and the first beam splitter in the traditional MZ modulated laser are realized with one continuous laser. The structure of the traditional MZ modulated laser can be greatly simplified, the chip size can be reduced, and the cost of the traditional MZ modulated laser chip can be greatly reduced.
[0033] The utility model is compatible with the material growth and process technology of the existing MZ modulated laser chip, and can be applied to all modulated laser chips based on phase modulation. In addition, the current MZ modulated laser packaging test can be simplified, which will greatly reduce the production cost of MZ modulated laser devices.
[0034] The utility model utilizes the same-phase optical characteristics of two same-direction output ends of the same laser, simplifies the structure of the existing Mach-Zehnder interference modulated laser, and only requires a phase-modulated optical waveguide and a beam combiner to achieve phase and intensity modulation of high-speed optical signals, thereby reducing the size of the externally modulated laser, improving the yield and output of the externally modulated laser, and providing a low-cost technical solution for large-scale application of externally modulated lasers. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Those skilled in the art should understand that the following description is only to schematically illustrate the principles of the present invention, which can be applied in a variety of ways to achieve many different alternative embodiments. These descriptions are only used to illustrate the general principles of the teaching content of the present invention and are not meant to limit the utility model concepts disclosed herein.
[0036] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the general description above and the detailed description of the drawings below, are used to explain the principles of the present invention.
[0037] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:
[0038] Figure 1 It is a schematic diagram of the structure of a traditional externally modulated laser chip based on a 3dB directional coupler in the prior art;
[0039] Figure 2 It is a schematic diagram of the structure of a traditional externally modulated laser chip based on multi-mode interferometer splitting and beam combining in the prior art;
[0040] Figure 3 It is a schematic diagram of the structure of an externally modulated laser chip based on a U-shaped laser and a 2X1 multi-mode interference beam combiner of the utility model;
[0041] Figure 3a It is a schematic diagram of the structure of a distributed Bragg reflector U-shaped laser;
[0042] Figure 4 It is a schematic diagram of the structure of an externally modulated laser chip based on a U-shaped laser and a 2X2 multi-mode interference beam combiner of the utility model;
[0043] Figure 5 It is a schematic structural diagram of an externally modulated laser chip based on a U-shaped laser and a 3dB directional coupling beam combiner of the utility model;
[0044] Figure 6 It is a structural schematic diagram of an externally modulated laser based on a U-shaped laser of a reflecting surface of the utility model;
[0045] Figure 7 This is a schematic diagram of the structure of an externally modulated laser based on a V-shaped laser of the utility model;
[0046] Figure 8 It is a schematic diagram of the structure of an externally modulated laser based on a Y-shaped laser of the utility model;
[0047] Fig. 9 It is a schematic diagram of the structure of a tunable U-shaped laser based on sampled grating laser.
[0048] Description of reference numerals in the figures:
[0049] Prior art
[0050] 1 is a semiconductor substrate, 2 is a continuous laser,
[0051] 3a is a 3dB directional coupling splitter, 3b is a 3dB directional coupling combiner,
[0052] 3am is a 1X2 multimode splitter, 3bm is a 2X2 multimode combiner,
[0053] 4a is a first phase modulated optical waveguide, 4b is a second phase modulated optical waveguide,
[0054] The utility model
[0055] 4a is a first phase modulated optical waveguide, 4b is a second phase modulated optical waveguide,
[0056] 5a is an electrical isolation area, 5b is another electrical isolation area,
[0057] 10a is a co-directional dual-output continuous U-shaped laser.
[0058] 10b is a U-shaped laser based on a reflective surface.
[0059] 10b1 is a reflection surface, 10b2 is another reflection surface,
[0060] 10b3 is a vertical straight waveguide, 10b4 is a horizontal straight waveguide
[0061] 10b5 is another horizontal straight waveguide.
[0062] 10c is a V-shaped co-directional dual-output laser.
[0063] 10c1 is a horizontal straight waveguide, 10c2 is another horizontal straight waveguide,
[0064] 10d1 is a curved waveguide, 10d2 is another curved waveguide,
[0065] 10e is the cavity surface with high reflection film.
[0066] 10f is a straight waveguide connecting two curved waveguides.
[0067] 10a1 is the gain region of the U-shaped laser,
[0068] 10m1 is the first Bragg reflector, 10m2 is the second Bragg reflector,
[0069] 10m3 is the first sampling grating, and 10m4 is the second sampling grating. DETAILED DESCRIPTION
[0070] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution of the embodiment of the utility model will be clearly and completely described in conjunction with the drawings of the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the described embodiment of the utility model, all other embodiments obtained by ordinary technicians in the field without creative work belong to the scope of protection of the utility model. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the utility model belongs. The "first", "second" and similar words used in this article do not indicate any order, quantity or importance, but are only used to distinguish different components. "Including" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right", etc. are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.
[0071] The core idea of the utility model is to use a laser with co-directional dual output waveguides to realize the functions of a continuous laser and a beam splitter in a traditional MZ modulated laser, thereby simplifying the structure and size of the MZ modulated laser and realizing a low-cost MZ modulated laser chip for long-distance transmission of high-speed optical signals.
[0072] The utility model aims at the function of the optical splitter in the traditional MZ modulated laser chip to distribute the light from the continuous laser to two phase waveguides and maintain a fixed phase difference. Based on the theory that the light from the front and rear ports of the same laser has the same phase, the output light of the rear end face of the continuous laser is creatively utilized, the light output from the front and rear ports is directly connected to the two phase waveguides 4a and 4b, and two paths of light are directly input from the light source with a fixed phase, thereby removing the optical splitter to simplify the design and manufacture of the existing MZ modulated laser chip.
[0073] In addition, because the laser's resonant cavity adopts a folded design, the laser's cavity length is doubled for the same length of semiconductor material. This will increase the chip output per unit area and further reduce costs for semiconductor lasers that require a long cavity structure, such as wavelength tunable lasers. Due to the symmetrical structure, the light at the two output ends of the laser not only has the same phase, but also the same intensity, which will help improve the performance and yield of the modulated laser.
[0074] In order to achieve the purpose of simplifying the MZ modulated laser chip structure based on the two-way output light of the front and rear ports of a single laser, the utility model is described through the following embodiments.
[0075] like Figure 3 As shown, the external modulated laser chip of the utility model includes a U-shaped laser 10a, two phase modulated optical waveguides 4a and 4b, an optical beam combiner 3bm, and two electrical isolation regions 5a and 5b located between the laser 10a and the modulation waveguides 4a and 4b, which are arranged in sequence from left to right. The two ports of the U-shaped laser 10a are connected to the phase modulated optical waveguides 4a and 4b through the electrical isolation regions 5a and 5b; the laser 10a is connected to a DC power supply through electrodes (not shown in the figure); the phase modulated optical waveguides 4a and / or 4b are connected to a modulation signal through another electrode (not shown in the figure). The U-shaped laser 10a is a continuously operating semiconductor laser.
[0076] Figure 3 The optical combiner 3bm is a 2X1 multimode interferometer (MMI). The waveguide of the U-shaped laser 10a consists of two straight waveguides connecting the phase modulated optical waveguides 4a and 4b and a section of curved waveguide. The waveguide region of the U-shaped laser 10a contains part or all of the grating structure. In order to achieve the purpose of equal laser power output from the two ports of the U-shaped laser 10a, the grating should be symmetrically arranged in the waveguide region of the U-shaped laser 10a. Because of the grating structure, the laser 10a will no longer need a cleaved cavity surface as a resonant cavity. Removing the phase uncertainty caused by the cleaved cavity surface will help improve the yield of single-mode lasers.
[0077] The laser based on the grating structure can be either a single-mode distributed feedback laser (DFB) or a distributed Bragg reflector (DBR) laser. Figure 3aIt is a schematic diagram of a distributed Bragg reflector (DBR) laser. It includes distributed Bragg reflectors (DBR) 10m1 and 10m2 at both ends, and a gain zone 10a1 in the middle. A phase adjustment zone can also be added to adjust the laser output wavelength. Based on the arrangement of the U-shaped waveguide structure, the two ports of the U-shaped waveguide of the laser 10a will simultaneously output continuous light with the same phase and intensity into the phase modulated optical waveguides 4a and 4b. If the phase difference between the phase modulated optical waveguides 4a and 4b is 0, then the two paths of light with the same phase will be coherently superimposed after passing through the output combiner 3bm to obtain a "1" signal; if the phase difference between the phase modulated optical waveguides 4a and 4b is 180 degrees, then the two paths of light with opposite phases will be coherently subtracted after passing through the output combiner 3bm to obtain a "0" signal, thereby realizing the modulated output of continuous light.
[0078] For the 1550nm band used in optical communication, all structures of the above modulated lasers are deposited on a semiconductor substrate (generally indium phosphide) by epitaxial growth (generally metal organic vapor phase epitaxy MOCVD). Generally, the epitaxial structure of the laser 10a is grown first, and then the secondary epitaxial growth phase modulation 4a and 4b and the structure of the combiner are provided. The epitaxial structure generally includes N-type semiconductor materials, active regions and P-type materials from bottom to top. After the material growth is completed, the waveguide structure is formed by etching. The width of the waveguide is generally about 1 to 3 microns. Etching is generally a combination of dry and wet methods. The laser 10a, the modulated waveguide 4a / 4b and the combiner 3bm are generally indium gallium arsenic phosphide (InGaAsP) or indium gallium aluminum arsenic (InGaAlAs) of different components. The active region of the laser 10a can be a quantum well structure.
[0079] like Figure 4 As shown, as another preferred embodiment of the utility model, the output end adopts a 2X2 multi-mode interferometer (MMI) structure, and the two modulated waveguides 4a and 4b have different waveguide lengths. In this way, one of the two output ends is used as an output signal, and the other can be used as a monitoring end for signal monitoring. Different from 2X1 MMI, the two output signals of the 2X2 combiner have a 90-degree phase difference, so it is generally necessary to design the waveguides of the two phase modulated optical waveguides 4a and 4b to be of different lengths. Before the modulated signal is added, the phase difference between the two phase modulated optical waveguides 4a and 4b is 90 degrees.
[0080] Figure 5 Another preferred embodiment of the utility model uses a 3dB directional coupler 3b instead of Figure 4 The 2X2MMI interferometer in.
[0081] The U-shaped waveguides in the above preferred embodiments are connected by curved waveguides. Generally, the curved waveguide is limited by the difference in waveguide refractive index and the bending radius cannot be too small. If it is necessary to further reduce the chip size, a miniaturized U-shaped waveguide can be realized by introducing two total reflection surfaces. Figure 6 As shown in FIG. 1 , as another preferred embodiment of the present invention, it at least comprises from left to right a continuous single-mode laser 10b, two phase-modulated optical waveguides 4a and 4b, and an output combiner 3b ( Figure 6 It is a 3dB directional coupler, and it can also be an MMI or Y-type combiner). The single-mode laser 10b is a U-shaped structure that includes two total reflection surfaces 10b1 and 10b2, a vertical waveguide 10b3 and two horizontal waveguides 10b4 and 10b5. The horizontal waveguides 10b4 and 10b5 are connected by the reflection surfaces 10b1 and 10b2 and the waveguide 10b3 to form the resonant cavity of the laser, thereby ensuring that the light input to the two phase-modulated optical waveguides 4a and 4b is two paths of light with the same phase. The refractive index of III-V semiconductor materials is greater than 3 between 1200 and 1600nm, so the critical angle of total reflection for air is less than 20 degrees. For Figure 6 In the example, the incident angle of light from the horizontal waveguides 10b4 and 10b5 and the vertical waveguide 10b3 is 45 degrees, which is much higher than the critical angle of total reflection. Therefore, the light from 10b4 and 105 can be totally reflected and coupled into 10b3, and vice versa. The total reflection surfaces 10b1 and 10b2 can be realized by dry etching, and the etching depth is greater than the size of the waveguide mode field. In order to reduce the requirements for the etching position accuracy, a tapered structure can be added to the waveguide near the reflection surfaces 10b1 and 10b2 to expand the size of the optical mode field, thereby reducing the influence of the etching accuracy on the optical coupling efficiency. In this embodiment, at least the horizontal waveguides 10b4 and 10b5 include a grating structure.
[0082] like Figure 7 As shown, as another preferred embodiment of the utility model, it at least includes a continuous laser 10c composed of a V-shaped waveguide from left to right, two phase-modulated optical waveguides 4a and 4b, and an output optical combiner 3b. The V-shaped waveguide includes two waveguides 10c1 and 10c2 in the horizontal direction, and curved waveguides 10d1 and 10d2 connected to the horizontal waveguides 10c1 and 10c2. The curved waveguides 10d1 and 10d2 intersect at equal angles in opposite directions on the laser end face 10e. A high-reflection (HR) film is coated on the laser end face 10e. In this way, the light from 10d1 will be reflected and coupled into 10d2 through the cavity surface 10e, and vice versa. This structure will solve the problem. Figure 5 In the example, the bending radius cannot be too small due to the difference in refractive index of the waveguide. On the other hand, the end face 10e can be formed by cleavage, without the need for Figure 6The example requires a special etching method to form the reflective surface, so Figure 7 The example will likely further simplify the fabrication of the modulated laser.
[0083] Figure 7 The V-shaped waveguide structure in the example can be further replaced by a Y-shaped one, that is, Figure 8 Another preferred embodiment is shown. In this embodiment, the curved waveguides 10d1 and 10d2 are S-shaped bends, and are connected to a straight waveguide 10f at the end of the laser cavity surface to form two coupled resonant cavities. One is composed of 10c1, 10d1, 10f and the cavity surface 10e with HR film; the other is composed of 10c2, 10d2, 10f and 10e. The two resonant cavities are symmetrically coupled together through 10f and 10e, thereby ensuring that the phases of the continuous light output from the two paths are consistent. Of course, the straight waveguide 10f can also be replaced by two mutually coupled double straight waveguides.
[0084] In the above embodiments of the utility model, the semiconductor laser is generally a single-mode DFB or DBR laser. However, many applications require the laser wavelength to be tunable. For narrow-band wavelength tunability, the grating region of the DBR laser can be injected with current or heated to change its refractive index to achieve wavelength tuning in the range of 5 to 12 nm. For broadband wavelength tunability, a sampled grating structure can be introduced. Fig. 9 The schematic diagram of a U-shaped tunable wavelength laser with a sampled grating structure. The structure includes at least two sampled gratings 10m3 and 10m4 with different sampling periods at the output end, and a gain waveguide 10a1. Generally, a phase adjustment region (not shown) may also be included. By controlling the refractive index of the sampled gratings 10m3 and 10m4 respectively, the wavelength of the laser can be varied over a wide range. The sampled grating structure can also be applied to the other U-shaped, V-shaped and Y-shaped lasers mentioned above to achieve the purpose of wavelength tunability.
[0085] In the above embodiments of the present invention, the semiconductor laser chip, the phase modulated optical waveguide and the optical combiner are integrated on a semiconductor substrate. Of course, a hybrid integration method can also be used to implement the idea of the present invention. For example, the laser is a III-V compound semiconductor material, the phase modulated optical waveguide and the optical combiner are silicon or lithium niobate materials or other electro-optical materials, and the modulator based on these materials can also save the splitter.
[0086] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these changes and modifications.
Claims
1. An externally modulated laser chip with an integrated Mach-Zehnder interferometer modulator, characterized in that: include: A laser with two waveguides to achieve dual outputs in the same direction; the laser is powered by direct current; the laser is a continuous laser; an optical beam combiner having dual input ports; as well as Two phase modulated optical waveguides, one end of which is connected to the two waveguides of the laser respectively, and the other end of which is connected to the two input ends of the optical combiner respectively; the phase modulated optical waveguide is driven by an AC modulated electrical signal.
2. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 1, characterized in that: The waveguide of the laser is a U-shaped structure.
3. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 2, characterized in that: The two waveguides are connected at the other end of the dual output through a bent waveguide to form the waveguide of the laser.
4. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 2, characterized in that: The two waveguides are connected at the other end of the dual outputs through two reflection surfaces and a waveguide in a vertical direction to form the waveguide of the laser.
5. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 1, characterized in that: The waveguide of the laser is a V-shaped structure.
6. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 5, characterized in that: The two waveguides are connected at the other end of the dual output through two bent waveguides.
7. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 6, characterized in that: The two bent waveguides are placed in opposite directions at the other end face of the laser and meet at the end face of the laser.
8. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 7, characterized in that: The end face of the laser is plated with a high reflection film.
9. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 1, characterized in that: The waveguide of the laser is a Y-shaped structure.
10. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 9, characterized in that: The two waveguides of the laser are connected to the same straight waveguide through a curved waveguide; the cavity surface end of the straight waveguide is plated with a high reflection film.
11. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 1, characterized in that: The optical combiner is a 1X2 multimode interferometer, a 2X2 multimode interferometer or a 3dB directional coupler.
12. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 1, characterized in that: The laser is a distributed feedback laser with a grating structure; Alternatively, the laser is a distributed Bragg reflector laser; Alternatively, the laser is a wavelength tunable laser.
13. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 1, characterized in that: The two phase modulated optical waveguides have different lengths, and one of them has a bent waveguide.
14. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 1 or 13, characterized in that: The phase modulation optical waveguide consists of two sections; one section is DC biased for phase adjustment, and the other section is connected to the modulation signal for signal modulation.
15. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 1, characterized in that: A semiconductor optical amplifier is integrated after the optical combiner.
16. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 1, characterized in that: The waveguide region of the laser contains part or all of the grating structure.
17. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 16, characterized in that: The gratings are arranged symmetrically in the waveguide region of the laser.
18. The externally modulated laser chip with integrated Mach-Zehnder interferometer modulator according to claim 1, characterized in that: The waveguide width of the laser is about 1 to 3 microns.