• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    An active graphene electro-optic modulator (7) according to the invention provides active mode-locking in a laser, which modulator comprises two electrodes (8A, 9A), which are connectable to an electric signal generator (10). The modulator (7) comprises a graphene layer (11) and an insulating layer (12), in which layers an electric signal generated by the electric signal generator (10) is arranged to provide an electric field. The light beam of the laser is arranged go through at least the graphene layer (11) and the insulation layer (12,), the insulating layer having a thickness, which is arranged to provide a designed modulation depth.
    公开号:FI20185200A1
    申请号:FI20185200
    申请日:2018-03-01
    公开日:2019-06-13
    发明作者:Zhipei Sun；Yadong Wang；Hui Xue；Jakub Boguslawski
    申请人:Aalto Univ Foundation Sr；
    IPC主号:
    专利说明:

    An active electro-optic modulator
    20185200 prh 01 -03- 2018
    Field of technology
    The invention relates to an active electro-optic modulator, which is used with a laser in order to provide a mode locking. Further the invention relates to lasers having electro-optic modulators.
    Prior art
    An electro-optic modulator (EOM) is a device which can be used for active mode locking of a laser. The electro-optic modulator controls the power, phase or polarization of a laser beam with an electrical control signal.
    Mode locking means techniques to produce ultrashort (typically <1ns) pulses with a laser. The duration of the ultrashort pulses can be on the order of picoseconds or even 15 femtoseconds. The basis of the mode locking is to introduce a fixed-phase relationship between the longitudinal modes (i.e. standing waves) of the laser's cavity. Normally each of these modes oscillates independently, with no fixed relationship between each other. The individual phase of the light waves may vary randomly, for example due to thermal changes in materials of the laser. When the longitudinal modes are fixed20 phased having relationship between them. The laser is said to be 'phase-locked' or 'mode-locked'. Interference between these modes causes the laser light to be produced as a train of pulses.
    There are several ways to obtain the mode locking, like active mode locking and passive mode locking. The active mode locking utilizes external course like electricity 25 to achieve the mode locking. The passive mode locking is based on a passive element within the laser cavity. The element provides a saturable absorption effect, which can be used for the passive mode locking. The functionality is optical-optical phenomena.
    20185200 prh 01 -03- 2018
    The electro-optic modulator typically contains one or two Pockels cells, and possibly additional optical components such as polarizers. Figures 1A and 1B illustrate two typical Pockels cells. Pockels cell operation is normally based on the linear electrooptic effect (also called the Pockels effect), which means the modification of the 5 refractive index of a nonlinear crystal by an electric field in proportion to the field strength.
    A Pockels cell has an electro-optic crystal 1A in Fig. 1A (a crystal 1B in Fig. 1B) with electrodes 2A, 3A (electrodes 2B, 3B in Fig. 1B) attached to it. The electrodes can be metal rings or transparent layers on the end faces with metallic contacts 5A, 6A, 5B,
    6B. A light beam 4A in Fig. 1A (light beam 4B in Fig. 1B) can propagate through the crystal. The phase delay in the crystal can be modulated by applying a variable electric voltage.
    The voltage required for inducing a phase change of π, is called the half-wave voltage. Fora Pockels cell, it is usually hundreds or even thousands of volts, so that a 15 high-voltage amplifier is required. Suitable electronic circuits can switch such large voltages within a few nanoseconds, allowing the use of EOMs as fast optical switches. A modulation with smaller voltages is sufficient, when a small amplitude or phase modulation is required.
    Normally, nonlinear crystal materials are used for EOMs, such as potassium di20 deuterium phosphate, potassium titanyl phosphate, beta-barium borate, lithium niobite, lithium tantalite and ammonium dihydrogen phosphate. In addition to these inorganic electro-optic materials, there are also special polymers for EOMs.
    The invention relates to the active mode locking ways. There are several techniques to achieve active mode locking. Current electro-optical modulators used for active 25 mode-locking of lasers are fabricated by using expensive materials. They also have some other limitations, like narrow bandwidth operation (from 10 to 100 nm, depending on the wavelength of operation), high insertion losses (5-7 dB) and relatively large crystal size (for example 40 mm).
    Short description
    The object of the invention is to alleviate or even eliminate the problems said above. 5 The object is achieved in a way described in the independent claims. Dependent claims illustrate different embodiments of the invention.
    An active electro-optic modulator according to the invention provides mode-locking in a laser. The modulator comprises two electrodes, which are connectable to an electric signal generator. The modulator comprises a graphene layer (or multiple 10 graphene layers) and an insulating layer, in which layers an electric signal generated by the electric signal generator is arranged to provide an electric field. A light beam of the laser is arranged to interact at least with the graphene layer. The thickness of the insulating layer is arranged to provide designed modulation performance.
    List of figures
    In the following, the invention is described in more detail by reference to the enclosed drawings, where
    20185200 prh 01 -03- 2018
    Figures 1A and 1Billustrate typical examples of known electro-optical modulators,Figure 2illustrates an example of an embodiment according to the invention,Figure 3illustrates an example of fiber laser wherein the embodiment ofFigure 2 is installed,Figure 4illustrates another example of an embodiment according to the invention,Figure 5illustrates a third example of an embodiment according to the invention,Figure 6illustrates a fourth example of an embodiment according to the invention,
    20185200 prh 01 -03- 2018
    Figure 7
    Figure 8
    Figure 9
    Figure 10
    Figure 11
    Figure 12
    Figure 13
    Figure 14
    Figure 15
    Figure 16 illustrates a fifth example of an embodiment according to the invention, illustrates a sixth example of an embodiment according to the invention, illustrates a seventh example of an embodiment according to the invention, illustrates an eight example of an embodiment according to the invention, illustrates a ninth example of an embodiment according to the invention, illustrates an example of fiber laser wherein the active electrooptic modulator is situated into the cavity of a ring-cavity fiber laser, illustrates an example of fiber laser wherein the active electrooptic modulator is situated into the cavity of a linear-cavity fiber laser, illustrates an example of fiber laser wherein the active electrooptic modulator is situated at the end the cavity of a linear-cavity fiber laser, illustrates an example of fiber laser wherein the active electrooptic modulator is situated on a side-polished fiber into the cavity of a ring-cavity fiber laser, and illustrates an example of fiber laser wherein the active electrooptic modulator is situated on a side-polished fiber into the cavity of a linear-cavity fiber laser.
    Description of the invention
    Figure 2 shows an embodiment an active electro-optic modulator 7 for providing mode-locking in a laser according to the invention. The modulator comprises two
    20185200 prh 01 -03- 2018 electrodes 8A, 9A, which are connectable to an electric signal generator 10 (Fig.3). The modulator comprises also a graphene layer 11 and an insulating layer 12. An electric signal generated by the electric signal generator 10 is arranged to provide an electric field in the graphene layer 11 and insulating layer 12. A light beam 13 of the laser is arranged to go through at least the graphene layer 11 and the insulation layer
    12. The insulating layer has a thickness, which is arranged to provide designed modulation performance. The bottom electrode 9A in Figure 2 is made of a reflective material, so the light beam reflects from it. The graphene layer and the insulating layer are transparent, for the light beam.
    The metal reflection electrode can, for example, be made of Ti/Au, having 5/130 nm thickness. Also the top electrode 8A can be made of the same material being connected to the graphene 11, which can be monolayer. The insulating (high-k dielectric material) layer 12 can, for example, be hafnium dioxide (HfO2) having thickness 187 nm. The insulating layer allows reducing the driving voltage of the modulator. The driving voltage is generated by the electric signal generator 10.
    The embodiment of figure 2 can, for example, be made by utilizing a base layer, for example a bottom metal contact 14. Next an example of a possible manufacturing process is described. The bottom metal contact is firstly patterned into a suitable size (such as 80 pm-diameter disk) via conventional electron beam lithography (EBL), 20 evaporation and lift-off process. Atomic layer deposition (ALD) process is then used to deposit HfO2 and other dielectric layer on the patterned metal contact, acting as a high permittivity insulator layer. Next, monolayer chemical vapor deposition (CVD) grown graphene is transferred to the insulator layer. Note that other fabrication method (e.g., mechanical exfoliation, liquid exfoliation, molecular beam epitaxy, chemical synthesis, 25 grown on SiC, precipitation from metals) can also be an option. Finally, metal titanium/gold (for example 5/50 nm thickness) contact is fabricated on the top of graphene for gating.
    Figure 3 illustrates an example of fiber laser 15 wherein the embodiment of Figure
    2, manufactured as described above, is installed. The laser is a ring-cavity laser, 30 because its elements are connected with fiber providing a ring cavity of the laser. The
    20185200 prh 01 -03- 2018
    10% (in this example) output coupler (OC) 20 extracts the radiation (light beam) outside the laser and also works like a mirror reflecting 90% of the radiation back to the cavity. The modulator 7 having the reflective electrode 9A, works also like another mirror of the laser.
    The graphene absorption is controlled by electrical tuning of its Fermi level. The Fermi level illustrates the most upper energy band level wherein the electrons occupies. The electric tuning is providing by the electric signal generator 10. The modelocking happens when a light pulse with the correct timing can effectively pass the modulator at times where the losses (absorption) are at minimum in graphene. The 10 correct timing depends on the wavelength and phase of the light pulse. The passed pulses with certain periods are amplified in the laser cavity due to a gain medium 16, and finally pass out through the output coupler 20.
    At zero voltage the Fermi level in graphene is in Dirac point or slightly shifted. When the voltage is applied, the graphene layer, which is one of the capacitor’s plates, 15 becomes doped by electrons (or holes depending on voltage polarization). This allows for gate-controlled shift in Fermi level. So, the graphene layer can become transparent due to the Pauli blocking, when it reaches the half photon energy of the incident light. Pauli blocking means that transition states for electrons are filled, so a next incoming electron can no longer do that transition between the energy bands.
    The example of the ring-fiber laser of figure 3 comprises other elements as well. An active gain medium 16 is 80 cm erbium doped fiber (EDF) with a peak absorption of 41 dB/m at 1530 nm in this example. The laser is forward-pumped by a 980 nm semiconductor laser diode 17 coupled into the cavity through a 980/1550 wavelengthdivision multiplexer 18, for example. The polarization independent isolator 19 ensures 25 clockwise, unidirectional operation, providing higher isolation than the circulator. So, the isolator ensures that the radiation propagates clockwise. The measurements of the EOM were performed with a typical EOM characterization setup (for example, in this example, a continuous wave (CW) laser diode at 1550 nm with 1 mW power). The modulation depth of 1.94% was obtained (in this example). The reflectance changed 30 linearly when the voltage from -5V up to 5V was applied in this example.
    20185200 prh 01 -03- 2018
    The polarization controller 21 is also included to adjust the intracavity polarization state. The graphene modulator 7 is inserted in a linear part of the cavity coupled with the ring-shaped part by a fiber circulator. The fiber circulator 22 is an element directing an incoming beam to the next port of the circulator at the clockwise direction (in this example). A fiber collimator 23 and an aspheric focusing lens 24 (in this example f = 4.63 mm) are used to extract the beam outside the fiber and focus at the surface of the modulator 7. The fiber collimator 23 is a device for collimating the light coming from a fiber, or for launching collimated light into the fiber. The beam size at the focal point is 18.6 pm. The total cavity length in this example of figure 3 is 47.6 m, which corresponds to 4.35 MHz fundamental repetition rate. The net cavity dispersion is anomalous and equal to approx. -1.094 ps2 (in this example).
    The thickness of the insulating layer is one of the parameters, affecting the EOM performance and thus the laser performance. In a high reflectivity mirror based design the incoming and reflected waves form a standing wave. By changing the position of graphene layer along the standing wave, it is possible to control the linear absorption and available modulation depth of the EOM. Adjustment of insulating layer thickness thus allows tailoring linear absorption of graphene from almost 0 (when graphene is placed in the node the standing wave) up to 1000% (when placed in the antinode of the standing wave, which corresponds to λΙ4 distance). In the measurement made by the applicant, the thickness of the HfO2 layer was chosen to bring the graphene close to the antinode of the standing wave. The measured insertion loss of the device was 12.85% at zero voltage (around 6.1% coming from graphene absorption).
    When considering the embodiment of Figure 3, the active mode-locking operation occurs immediately when the modulating signal frequency is set to precisely match the round-trip frequency of the laser cavity (f0 = 4.3505725 MHz), and the pump power exceeds the lasing threshold (18 mW). When the amplitude of the modulating electrical signal was set to 8 V (from -4 to 4 V), the best stability of the output laser pulses was observed in this measurement. The mode-locking operation is lost after detuning the driving frequency by <100 Hz. Stable pulses were generated regardless of the polarization controller 21 setting. However, the polarization controller may slightly adjust the output pulse duration.
    20185200 prh 01 -03- 2018
    The active mode-locking with output pulse duration of 1.44 ps (in this example) and pulse energy of 844 pJ at <1559 nm wavelength (Erbium doped gain fiber is used in this example) was achieved for synchronized longitudinal modes of an erbium-doped fiber laser.
    The electrical signal generator allows generating various electrical signals, including sine wave and square wave with the controlled filling factor. The mode-locking operation was possible with both signal shapes. The shortest pulses were observed using square wave with 10% filling factor. When using this shape of the electric signal, the modulator is Open’ for a shorter time, which facilitates the shortening of the pulse 10 duration.
    The example of figure 3 demonstrates also that the laser provides stable modelocking operation for a broad range of pump power starting from 18 mW up to 129 mW. For higher pump power the laser operation becomes unstable. The enough higher pump power can provide passive mode-locking. However, in the invention, the actively 15 mode-locking operation can occur immediately when the pump power exceeds the lasing threshold. So, the actively mode-locking works with low power threshold. The output power and single pulse energy typically grow linearly together with the pump power. The highest output power was recorded to be 3.7 mW in the measurements, which corresponds to pulse energy of 844 pJ in this example.
    The obtained pulses are much shorter than Kuizenga-Siegman limit, which sets theoretically in certain simple conditions the shortest duration of actively mode-locked pulses for a given modulation strength and frequency, as well as laser cavity parameters. The reason for this is the nonlinear pulse shortening effect (i.e. anomalous dispersion and self-phase modulation). Any case, this indicates that the invention 25 provides very good level of the pulses with respect to their duration. The output pulse train from the laser was observed to have excellent pulse-to-pulse amplitude stability. The measured pulse separation was 228 ns, which corresponds to the fundamental repetition rate of the cavity of Figure 3.
    Figures 4-11 illustrate other possible embodiments of the modulator according to 30 the invention. Figure 4 shows an example 71 wherein there are two graphene layers
    20185200 prh 01 -03- 2018
    11, 11A. One graphene layer 11 is on the surface of the insulation layer 12A, and it is connected to an electrode 8B, so in this way it can be said to act as a part of the electrode. The other graphene layer 11A is also connected to another electrode 9B. There is a separate reflective layer 25 in order to reflect the light beam 13 in this embodiment. As can be seen the other graphene layer is inserted into the insulation layer.
    Figure 5 shows an example 72 wherein there is one graphene layer 11. The graphene layer 11 is on the surface of the insulation layer 12C, and it is connected to an electrode 8B, so it acts as a part of the electrode. The other electrode 9C is on the 10 other side’s surface of the insulation layer. The other insulating layer can be a reflective layer in which case a light beam 13 reflects. The other insulating layer can also be a transparent layer in which case a light beam 13 goes through the electrode 9C.
    Figure 6 shows an example 73 wherein there are two graphene layers 11,11B. One graphene layer 11 is on the surface of the insulation layer 12D, and it is connected to 15 an electrode 8D. The other graphene layer 11B is also on the other surface of the insulating layer, on the other side, and connected to another electrode 9D. In this embodiment the light beam 13 goes through the modulator 73.
    Figure 7 shows an example 74 wherein there is one graphene layer 11C inside the insulation layer 12E. The electrodes 8E, 9E are on the surfaces of the insulation layer, 20 at opposite sides of the insulation layer. The both electrodes are transparent, so the light beam 13 goes through the modulator 74 Figure 8 shows a variation example 75 of the embodiment of figure 7. The embodiment 75 of figure 8 has two graphene layers (11D) inside the insulation layer (12E).
    As can be seen the electrodes can be situated on the opposite sides of the 25 insulating layer, and the graphene layer can be on a surface of the insulating layer being in contact with the electrode on the same surface, or the graphene layer is inside the insulating layer. There can be two or more insulating layers in the modulator. At least one graphene layer can be inside the insulating layer, and at least one graphene layer on at least one surface of the insulating layer. The both electrodes can be made
    20185200 prh 01 -03- 2018 of transparent materials, or one electrode can be made of transparent material and the other electrode can be made of reflective material.
    Figures 9 and 10 show embodiments where the modulator 76, 77 is directly installed on a fiber-tip. The fiber 26 is coated by a cladding 27. The transparent embodiment 76 5 of figure 9 comprises two graphene layers 11E, 11F on the both surfaces of the insulating layer 12F. The electrodes 8F, 9F are connected to the graphene layers in such a way that they do not disturb the light beam 13 going through the modulator. In the reflective embodiment of figure 10, the reflective electrode 8F on the other surface of the insulating layer 12G reflects the light beam back to the fiber 26 through the 10 insulating layer 12G and the graphene layer 11G.
    Figure 11 shows an example of a modulator, which is installed on a side-polished fiber 26 into the cavity of the laser. The cladding 27 has been cut away on one side of the fiber, which makes it possible to install the modulator 78 on the side of the fiber 26. The graphene layer 11H, which is connected to an electrode 9F can allow the light 15 beam enter the isolation layer 12H.
    Figures 12-16 show different embodiments of lasers wherein the inventive modulator is installed. Figure 12 illustrates a ring-cavity laser having an active electrooptic modulator 72 into the cavity of the laser. The modulator is connected to an electric signal modulator 10. Lenses 24 are on the both sides of the modulator in order to focus 20 the radiation in the cavity to the modulator 72. When comparing this embodiment with the embodiment of figure 3, it can be noted that the embodiment of figure 12 is designed so that no collimator/s is needed. So, each laser can be designed individually. For example, the polarization controller 21 is not installed if properties of the elements of a laser allow this.
    Figure 13 shows an example of a linear-cavity fiber laser wherein an active electrooptic modulator 72 is installed. 72 into the cavity of the laser. The modulator is connected to an electric signal generator 10. Lenses 24 are on the both sides of the modulator in order to focus the radiation in the cavity to the modulator 72. There are mirrors 34 at the both end of the cavity in order reflect the radiation in the cavity. The 30 gain medium 16 and the fiber 33 of the laser are illustrated schematically as circles in
    20185200 prh 01 -03- 2018 order to show that the length of the gain medium and the length of the fiber can be designed to be any suitable lengths. Different gain fiber can be used for gain medium 16. As can be seen the examples of figure 12 and figure 13 show embodiments wherein the electro-optic modulator 72 allows the light beam to go through the modulator, and the modulator is installed into the cavity of the fiber laser. So, the both electrodes can be transparent material allowing the light beam of the laser going through the modulator.
    Figures 3 and 14 show examples wherein the electro-optic modulator 7 has the electrode made of the reflective material for reflecting the light beam of the laser. So, 10 the modulator can act as mirror, and the modulator can be installed on one end of the cavity of the laser. Therefore, the modulator 7 can replace the mirror 34 at the other end of the cavity. If the modulator is directly installed on a fiber-tip/s as illustrated in figures 9 and 10, the lense/s 24 and the collimator/s 23 are not needed in linear-cavity or ring-cavity fiber lasers.
    Figures 15 and 16 show embodiments wherein the modulator 78 is installed on a side-polished fiber 26 into the cavity of the laser. See figure 11. The modulator is connected to an electric signal generator 10. As can be seen this type of a modulator can also be installed in a ring-cavity or a linear-cavity fiber laser.
    Although, the base layer 14 is showed only in some embodiments above, it is clear 20 that every embodiment of the invention may comprise it. Any inventive embodiment may also comprise further layers for protecting the other layers.
    The invention can also be used in solid state lasers and semiconductor lasers. For example, a solid-state laser is a laser wherein a gain medium is solid material. For example, crystalline or glass which is doped can be used as the gain medium. Although 25 the fiber lasers have a solid gain medium, they are called fiber lasers. The light is guided due to the total internal reflection in the optical fiber. It is also possible to build the inventive modulator on a silicon chip, with CMOS (complementary metal-oxidesemiconductor) integrated optics. So, it is possible to provide a chip-scale modelocking laser. As indicated above, the semiconductor-based lasers are also in the solid 30 state but are generally considered as a separate class from solid-state lasers. The
    20185200 prh 01 -03- 2018 invention is possible to produce shorter pulses than that in current actively mode locked lasers wherein pulse durations are significantly longer than those of passively mode locked lasers. Further advantages are that actively mode locked lasers produce pulses with higher repetition rate and excellent phase stability and without dropouts of pulses.
    So, the modulator structure having a graphene layer or layers with an insulation layer makes it possible to produce high quality shorter pulses than known active modelocking lasers produce. The graphene absorption is controlled by electrical tuning of its Fermi level, which allows to electrically control the repetition rate of generated pulses for higher repetition rate.
    The invention combines advantages of simple design, small footprint, broad operation bandwidth, robust performance and huge potential for integration with, for example, fiber or silicon-on-chip platform. The size of the inventive modular can be much smaller than in known solutions. The inventive structure can be used in industrial laser applications, in material processing, surgery applications and in 15 telecommunications just to mentioning some applicable areas.
    Actively mode-locked lasers offer large degrees of flexibility for a wider range of applications. Graphene, with advantages of broad-operation bandwidth, fast transition time, and high flexibility, is illustrated in this description to be suitable for the active mode-locking. Graphene based electric-optic modulator can work in a range 20 wavelengths from visible to even millimeter. So the invention can be utilized in this large range with proper gain media.
    As summary, the inventive modulators with graphene distinguish with broader operation bandwidth, lower insertion loss and smaller dimensions. The active modelocking technique, together with nonlinear pulse shortening, promises, for example, the 25 generation of transform-limited 1.4 ps pulses with energy of 844 pJ. The invention provides a practical and effective approach for actively mode-locked operation.
    It is evident from the above that the invention is not limited to the embodiments described in this text but can be implemented in many other different embodiments within the scope of the independent claims.
    权利要求:
    Claims (5)
    [1] 1. An active electro-optic modulator (7, 72) for providing mode-locking in a laser, which modulator comprises two electrodes (8A, 9A, 8C, 9C), which are connectable to an electric signal generator (10), characterised in that the modulator (7, 72) comprises
    5 a graphene layer (11) and an insulating layer (12, 12C), in which layers an electric signal generated by the electric signal generator (10) is arranged to provide an electric field, and a light beam of the laser is arranged to go through at least the graphene layer (11) and the insulation layer (12, 12C), the insulating layer having a thickness, which is arranged to provide a designed modulation performance.
    10
    [2] 2. An active electro-optic modulator according to claim 1, characterised in that the electrodes (8A, 9A, 8C, 9C) are situated on the opposite sides of the insulating layer (12, 12C), and the graphene layer (11) is on a surface of the insulating layer being in contact with the electrode on the same surface, or the graphene layer (11) is inside the insulating layer (12).
    15
    [3] 3. An active electro-optic modulator according to claim 2, characterised in that there are two or more insulating layers (12, 12C).
    [4] 4. An active electro-optic modulator according to claim 3, characterised in that there is at least one graphene layer (11) inside the insulating layer (12, 12C), and at least one graphene layer (11) on at least one surface of the insulating layer.
    20 5. An active electro-optic modulator according to claim 2, characterised in that the both electrodes (8A, 9A, 8C, 9C) are made of transparent material, or one electrode is made of transparent material and the other electrode is made of reflective material.
    6. An active electro-optic modulator according to any of claim 1 - 5, characterised it is installed into a ring-cavity fiber laser (15, 28, 31) or a linear-cavity fiber laser (29,
    25 30,32).
    7. An active electro-optic modulator according to claim 6, characterised in that when the electro-optic modulator (7, 72) has the electrode made of the reflective material for reflecting the light beam of the laser, the modulator is installed on one end of the cavity of the laser (15, 30).
    30 8. An active electro-optic modulator according to claim 6, characterised in that the electro-optic modulator (7, 72) comprises a layer (25) made of the reflective material
    20185200 prh 01 -03- 2018 for reflecting the light beam of the laser, the modulator being installed on one end of the cavity of the laser (15, 30).
    9. An active electro-optic modulator according to claim 7 or 8, characterised in that the modulator (76, 77) is directly installed on a fiber-tip (26).
    [5] 5 10. An active electro-optic modulator according to claim 6, characterised in that when the both electrodes (8C, 9C) are transparent allowing the light beam of the laser going through the modulator, the modulator is installed into the cavity of the laser (28, 29, 31, 32).
    11. An active electro-optic modulator according to claim 10, characterised in that 10 modulator (76, 77) is directly installed on fiber-tips (26).
    12. An active electro-optic modulator according to claim 6, characterised in that the modulator (78) is installed on a side-polished fiber (26) into the cavity of the laser (31, 32).
    13. An active electro-optic modulator according to any of claim 6-12, characterised
    15 in that the electrodes (8A, 9A, 8C, 9C) are connected to the electric signal generator.
    14. An active electro-optic modulator according to claim 13, characterised in that the modulator comprises a base plate (14).
    15. An active electro-optic modulator according to any of claim 1 - 5, characterised in that it is installed into a solid state laser.
    20 16. An active electro-optic modulator according to any of claim 1 - 5, characterised in that it is installed into a semiconductor laser.
    17. An active electro-optic modulator according to any of claim 1 - 5, characterised in that it is built on a silicon chip, with CMOS integrated optics.
    18. An active electro-optic modulator according to any of claim 1-17, characterised
    25 in that two-dimensional layered material active modulators are used.
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    2021-10-20| MM| Patent lapsed|
    优先权:
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    FI20176105|2017-12-12|
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