Electro-optic modulator, photonic integrated chip and optical module

Abstract

An electro-optic modulator (100), a photonic integrated chip and an optical module. The electro-optic modulator (100) comprises a pair of modulation arms (10), wherein each modulation arm (10) comprises a ridge portion (11), and slab portions (12a, 12b) connected to two lateral sides of the ridge portion (11); each modulation arm (10) has a P-type region (15) and an N-type region (16) that are arranged side by side in a transverse direction, and a longitudinal PN junction (14) formed in the ridge portion (11); the height of the slab portions (12a, 12b) is within 1 / 3 of the height of the ridge portion (11); and the transverse width of the ridge portion (11) is 0.8-1.5 times the height thereof. Compared with conventional flat-structured ridge-type electro-optic modulation structures, the electro-optic modulator (100) can enable, by means of increasing the etching depth of the slab portions (12a, 12b), an optical signal to operate in a TM mode in the electro-optic modulator (100), such that the direction of an optical field is consistent with that of the PN junction, and the optical field has a high degree of overlap with a depletion region of the PN junction, thus improving the modulation efficiency of the electro-optic modulator (100).

Description

Electro-optical modulator, photonic integrated chip and optical module

[0001] The present application claims priority to the Chinese patent application No. 202421932978.7, filed on August 9, 2024, and entitled "Electro-optical modulator, photonic integrated chip and optical module", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The utility model belongs to optical communication element manufacturing technical field, concretely relates to a kind of electro-optical modulator, photonic integrated chip and optical module. BACKGROUND

[0003] Silicon optical chip can effectively reduce the cost and power consumption of module in optical communication system, and is a key technology to realize optical interconnection. Electro-optical modulator is one of the most important active devices in silicon optical chip, and plays an extremely important role in high-speed optical communication. Its function is to convert high-speed changing electrical signal into high-speed changing optical signal.

[0004] The phase shift region of a typical electro-optical modulator is a ridge waveguide structure, specifically including a ridge portion and a slab portion. The ridge portion is usually a transverse flat structure and is adapted to horizontal polarized light (TE), but the PN junction of the ridge portion is longitudinally distributed. In this way, in the phase shift region of the electro-optical modulator, the coincidence of the optical field and the PN junction depletion region is poor due to the inconsistency in direction between the longitudinal PN junction and the transverse optical field, which further leads to limited modulation efficiency of the electro-optical modulator and low modulation efficiency. SUMMARY

[0005] To solve the problem of limited modulation efficiency, the purpose of the utility model is to provide an electro-optical modulator, a photonic integrated chip and an optical module.

[0006] To achieve the above-mentioned purpose, an embodiment provides an electro-optical modulator. The electro-optical modulator includes a pair of modulation arms, each of which includes a ridge portion and a slab portion connected to the transverse two sides of the ridge portion.

[0007] The modulation arm has a P-type region and an N-type region transversely side by side, and a longitudinal PN junction formed in the ridge portion.

[0008] The height of the slab portion is within 1 / 3 of the height of the ridge portion; and the transverse width of the ridge portion is 0.8-1.5 times its height.

[0009] As a further improvement of an embodiment, the transverse width of the ridge portion is 150-550 nm, and the height of the ridge portion is 250-400 nm.

[0010] As a further improvement of the embodiment, the lateral width of the flat plate portion is not less than 100 nm.

[0011] As a further improvement of the embodiment, the modulation arm further comprises a step portion connected to the lateral end of the flat plate portion and away from the ridge portion, the height of the step portion is greater than the height of the flat plate portion.

[0012] As a further improvement of the embodiment, the step portion is configured as a single-step structure or a multi-step structure, the height of the step portion is within 2 / 3 of the height of the ridge portion.

[0013] As a further improvement of the embodiment, the modulation arm further comprises a contact portion connected to the lateral end of the step portion and away from the ridge portion.

[0014] The electro-optical modulator further comprises two electrodes, one of the electrodes is electrically connected to one of the contact portions, and the other of the electrodes is electrically connected to the other of the contact portions.

[0015] As a further improvement of the embodiment, the height from the flat plate portion to the contact portion increases sequentially at any lateral side of the ridge portion.

[0016] As a further improvement of the embodiment, the P-type region and the N-type region each have a lightly doped region, a medium doped region and a heavily doped region arranged sequentially away from the PN junction in the lateral direction.

[0017] The flat plate portion and the ridge portion intersect at the lightly doped region, the flat plate portion and the step portion intersect at the lightly doped region, the medium doped region or the heavily doped region, and the step portion and the contact portion intersect at the heavily doped region.

[0018] As a further improvement of the embodiment, the P-type region and the N-type region are configured to be mirror-symmetric with respect to the PN junction.

[0019] As a further improvement of the embodiment, the electro-optical modulator further comprises a beam splitter and a beam combiner, and a pair of the modulation arms are connected in parallel between the beam splitter and the beam combiner.

[0020] To achieve the above object, an embodiment provides a photonic integrated chip. The photonic integrated chip comprises a first polarization rotation unit and the electro-optical modulator arranged sequentially along an optical path.

[0021] The first polarization rotation unit is configured to change a received horizontally polarized light into a vertically polarized light.

[0022] The electro-optical modulator is configured to receive the vertically polarized light and modulate the vertically polarized light.

[0023] As a further improvement of an embodiment, the photonic integrated chip further comprises a second polarization rotation unit located at an output end of the electro-optical modulator, the second polarization rotation unit being configured to receive the modulated vertically polarized light and change the vertically polarized light into the horizontally polarized light.

[0024] As a further improvement of an embodiment, the photonic integrated chip further comprises:

[0025] a total beam splitter located in an incident light path of the first polarization rotation unit, or located in an optical path between the first polarization rotation unit and the electro-optical modulator.

[0026] To achieve the above object, an embodiment provides an optical module. The optical module comprises an optical emission unit and the photonic integrated chip,

[0027] the first polarization rotation unit being configured to change the horizontally polarized light emitted by the optical emission unit into the vertically polarized light, and the electro-optical modulator being configured to receive the vertically polarized light and modulate the vertically polarized light.

[0028] Compared with the prior art, the electro-optical modulator of the present application can make the optical signal work in a vertically polarized light (TM) mode in the electro-optical modulator by increasing the etching depth of the flat plate part, that is, the electro-optical modulator can be applied to modulate the vertically polarized light, so that the direction of the optical field is consistent with the direction of the PN junction, the coincidence degree of the optical field and the PN junction depletion region is good, and the modulation efficiency of the electro-optical modulator is improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Fig. 1 is a structural schematic diagram of an electro-optical modulator according to an embodiment of the present application;

[0030] Fig. 2 is a module schematic diagram of an optical path of the electro-optical modulator according to the embodiment of the present application;

[0031] Fig. 3 is a schematic block diagram of a photonic integrated chip according to the embodiment of the present application;

[0032] Fig. 4 is a structural schematic diagram of an electro-optical modulator according to an embodiment of the present application;

[0033] Fig. 5 is a schematic block diagram of a photonic integrated chip according to an embodiment of the present application;

[0034] Fig. 6 is a schematic block diagram of a photonic integrated chip according to an embodiment of the present application. DETAILED DESCRIPTION

[0035] The utility model will be described in detail below in combination with the specific embodiments shown in the drawings. However, these embodiments do not limit the utility model, and the changes in structure, method or function made by those skilled in the art based on these embodiments are all included in the protection scope of the utility model.

[0036] Embodiment 1

[0037] Referring to FIG. 1 and FIG. 2, the embodiment provides an electro-optical modulator 100 for modulating a received optical signal and outputting the modulated optical signal.

[0038] Specifically, referring to FIG. 1, the electro-optical modulator 100 includes a pair of modulation arms 10, each of which includes a P-type region 15 and an N-type region 16.

[0039] The P-type region 15 and the N-type region 16 are arranged side by side in a first direction, and a PN junction 14 extending in a second direction is formed between them, wherein the first direction and the second direction are perpendicular to each other.

[0040] For the convenience of understanding and description, in this application, the first direction is defined as the lateral direction, and the second direction is defined as the longitudinal direction, that is, the lateral direction is defined by the relative position of the P-type region 15 and the N-type region 16, and the longitudinal direction is defined by the protruding direction of the PN junction 14.

[0041] When the electro-optical modulator 100 is working, by applying an electrical signal to the P-type region 15 and the N-type region 16 respectively, a depletion region is generated at the PN junction 14, so that the effective refractive index of the optical signal propagating in the modulation arm 10 changes, thereby changing the phase of the optical signal and realizing the modulation of the optical signal.

[0042] In terms of configuration, the modulation arm 10 includes a ridge portion 11 and flat plate portions 12a, 12b connected to the lateral sides of the ridge portion 11.

[0043] Among them, the flat plate portion 12a is connected to one lateral side of the ridge portion 11, and the flat plate portion 12a and a part of the ridge portion 11 are formed in the P-type region 15; while the flat plate portion 12b is connected to the other lateral side of the ridge portion 11, and the flat plate portion 12b and the other part of the ridge portion 11 are formed in the N-type region 16.

[0044] The height of the flat plate portions 12a, 12b is less than the height of the ridge portion 11, which can be processed by etching process. The ridge portion 11 protrudes longitudinally relative to the flat plate portions 12a, 12b.

[0045] The PN junction 14 is formed in the ridge portion 11 and its extension direction is basically consistent with the protruding direction of the ridge portion 11.

[0046] In the present application, the lateral width W of the ridge portion 11 is 0.8-1.5 times the height H thereof, i.e. 0.8H≤W≤1.5H; the height of the flat plate portions 12a, 12b is ≤H / 3.

[0047] Here, the "lateral width of the ridge portion 11" refers to the dimension of the ridge portion 11 in the second direction, for example, the ridge portion 11 has a side edge 111 protruding longitudinally from the flat plate portion 12a at one lateral end and a side edge 112 protruding longitudinally from the flat plate portion 12b at the other lateral end, the side edges 111 and 112 are substantially parallel and opposite in the lateral direction, and the distance between the two defines the lateral width of the ridge portion 11.

[0048] Similarly, in the present application, the "height of the ridge portion 11" refers to the dimension of the P-type region 15 and the N-type region 16 constituting the ridge portion 11 in the first direction, i.e. in the direction parallel to the protruding direction of the ridge portion 11; similarly, the height of the flat plate portion 12a refers to the dimension h of the P-type region 15 constituting the flat plate portion 12a in the first direction, and the height of the flat plate portion 12b refers to the dimension h of the N-type region 16 constituting the flat plate portion 12b in the first direction.

[0049] Thus, compared with the conventional flat-structure ridge portion 11, the present application can make the optical signal work in the vertical polarization light (TM) mode in the electro-optical modulator 100 by increasing the etching depth of the flat plate portions 12a, 12b, i.e. the electro-optical modulator 100 can be suitable for modulating the vertical polarization light, so that the light field direction is consistent with the direction of the PN junction 14, the coincidence degree of the light field and the PN junction depletion region is good, and the modulation efficiency of the electro-optical modulator 100 is improved.

[0050] It should be noted that the height of the flat plate portion 12a and the height of the flat plate portion 12b can be set to be the same, for example, as shown in the figure, denoted by the same symbol h; and in the present application, the height of the flat plate portion 12a and the height of the flat plate portion 12b can also be set to be different.

[0051] The lateral width W of the ridge portion 11 is 150-550 nm, and the height H of the ridge portion 11 is 250-400 nm.

[0052] The lateral width w of the flat plate portion 12a is not less than 100 nm, and similarly, the lateral width w of the flat plate portion 12b is also not less than 100 nm.

[0053] Here, the lateral width of the flat plate portion 12a and the lateral width of the flat plate portion 12b can be set to be the same, for example, as shown in the figure, denoted by the same symbol w; and in the present application, the lateral width of the flat plate portion 12a and the lateral width of the flat plate portion 12b can also be set to be different.

[0054] Further, the modulation arm 10 further comprises a contact portion 13a, 13b.

[0055] In the embodiment, the contact portion 13a is connected with the lateral end of the flat portion 12a and faces away from the ridge portion 11, i.e. the contact portion 13a and the ridge portion 11 are separated at the lateral ends of the flat portion 12a; the contact portion 13b is connected with the lateral end of the flat portion 12b and faces away from the ridge portion 11, i.e. the contact portion 13b and the ridge portion 11 are separated at the lateral ends of the flat portion 12b.

[0056] Each modulation arm 10 further comprises an electrode 191, 192 located around the modulation arm 10. The electrode 191 is electrically connected with the contact portion 13a, in particular through the conductive via structure 18; similarly, the electrode 192 is electrically connected with the contact portion 13b, in particular through the conductive via structure 18.

[0057] Thus, when the electro-optical modulator 100 is in operation, the electrodes 191, 192 apply electrical signals to the P-type region 15 and the N-type region 16 respectively, so that the P-type region 15 is at a low potential and the N-type region 16 is at a high potential, and a depletion region is generated at the PN junction 14, which changes the effective refractive index of the light signal propagating in the modulation arm 10, thereby changing the phase of the light signal and achieving modulation of the light signal.

[0058] Further, on one lateral side of the ridge portion 11, the height of the flat portion 12a to the contact portion 13a increases successively, i.e. the height of the contact portion 13a is greater than the height of the flat portion 12a; similarly, on the other lateral side of the ridge portion 11, the height of the flat portion 12b to the contact portion 13b increases successively, i.e. the height of the contact portion 13b is greater than the height of the flat portion 12b.

[0059] In the embodiment, the height of the contact portion 13a, 13b is substantially consistent with the height H of the ridge portion 11.

[0060] Further, the P-type region 15 has a P-type lightly doped region 151, a P-type moderately doped region 152 and a P-type heavily doped region 153 arranged successively away from the PN junction 14 in the lateral direction. It can be understood that the P-type lightly doped region 151, the P-type moderately doped region 152 and the P-type heavily doped region 153 are all P-type doped and the doping concentration increases successively. Optionally, the doping concentration of the P-type lightly doped region 151 is 1 x 1016cm-3, the doping concentration of the P-type moderately doped region 152 is 1 x 1018cm-3, and the doping concentration of the P-type heavily doped region 153 is 1 x 1020cm-3. 16 cm -3 ~1 x 1018cm-3 18 cm -3 ~1 x 1018cm-3 17 cm -3 ~1 x 1018cm-3 20 cm -3, the doping concentration of the P-type heavily doped region 153 is 1×10 19 cm -3 ~1×10 22 cm -3 .

[0061] Similarly, the N-type region 16 has the N-type lightly doped region 161, the N-type moderately doped region 162 and the N-type heavily doped region 163 arranged in sequence along the transverse direction away from the PN junction 14. It can be understood that the N-type lightly doped region 161, the N-type moderately doped region 162 and the N-type heavily doped region 163 are all N-type doped, and the doping concentration increases in sequence. Optionally, the doping concentration of the N-type lightly doped region 161 is 1×10 16 cm -3 ~1×10 18 cm -3 , the doping concentration of the N-type moderately doped region 162 is 1×10 17 cm -3 ~1×10 20 cm -3 , and the doping concentration of the N-type heavily doped region 163 is 1×10 19 cm -3 ~1×10 22 cm -3 .

[0062] In this embodiment, the flat plate portion 12a and the ridge portion 11 intersect at the P-type lightly doped region 151, and the flat plate portion 12a and the contact portion 13a intersect at the P-type heavily doped region 153. That is, part of the P-type lightly doped region 151 is located in the ridge portion 11, and the other part is located in the flat plate portion 12a; part of the P-type heavily doped region 153 is located in the contact portion 13a, and the other part is located in the flat plate portion 12a; and the P-type moderately doped region 152 is located in the flat plate portion 12a.

[0063] The flat plate portion 12b and the ridge portion 11 intersect at the N-type lightly doped region 161, and the flat plate portion 12b and the contact portion 13b intersect at the N-type heavily doped region 163. That is, part of the N-type lightly doped region 161 is located in the ridge portion 11, and the other part is located in the flat plate portion 12b; part of the N-type heavily doped region 163 is located in the contact portion 13b, and the other part is located in the flat plate portion 12b; and the N-type moderately doped region 162 is located in the flat plate portion 12b.

[0064] That is, the P-type heavily doped region 153 of the P-type region 15 is electrically connected with the electrode 191, and accesses a relatively low potential through the electrode 191; and the N-type heavily doped region 163 of the N-type region 16 is electrically connected with the electrode 192, and accesses a relatively high potential through the electrode 192.

[0065] In the embodiment, the shape of the modulation arm 10 is set to be mirror-symmetrical with the PN junction 14 as the plane of symmetry. Correspondingly, in the ridge portion 11, the lateral width of the N-type lightly doped region 161 of the N-type region 16 and the lateral width of the P-type lightly doped region 151 of the P-type region 15 are the same, and the height of the N-type lightly doped region 161 and the height of the P-type lightly doped region 151 are the same; the height of the flat plate portion 12a and the flat plate portion 12b is the same, and the width is also the same; the height of the contact portion 13a and the contact portion 13b is the same, and the width is also the same.

[0066] In addition, the doping ion types of the P-type lightly doped region 151 and the N-type lightly doped region 161 are different, but the doping concentrations are basically the same (for example, of the same order of magnitude); similarly, the doping ion types of the P-type middle doped region 152 and the N-type middle doped region 162 are different, but the doping concentrations are basically the same (for example, of the same order of magnitude); and similarly, the doping ion types of the P-type heavily doped region 153 and the N-type heavily doped region 163 are different, but the doping concentrations are basically the same (for example, of the same order of magnitude).

[0067] Further, referring to FIG. 2, the electro-optical modulator 100 further includes a beam splitter 101 and a beam combiner 102. A pair of modulation arms 10 are arranged in parallel between the beam splitter 101 and the beam combiner 102.

[0068] In the application of the electro-optical modulator 100, the vertically polarized light received by the electro-optical modulator 100 is first split into two beams of vertically polarized light by the beam splitter 101, one of which is output to one modulation arm 10 for modulation, and the other of which is output to the other modulation arm 10 for modulation. The two beams of vertically polarized light after modulation are both output to the beam combiner 102, which combines them into one beam of vertically polarized light, which is then output.

[0069] Specifically, the electro-optical modulator 100 can be a Mach-Zehnder modulator (MZM for short).

[0070] Further, referring to FIG. 3, the embodiment also provides a photonic integrated chip, which includes the electro-optical modulator 100.

[0071] Specifically, the photonic integrated chip includes a first polarization rotation unit 201 and the electro-optical modulator 100 arranged in sequence along the direction of optical transmission.

[0072] That is, the first polarization rotation unit 201 is relatively in front, and the electro-optical modulator 100 is relatively in back. In this application, “front” and “back” are defined on the basis of the direction of light transmission, “front” means that the light signal reaches first in the optical path, and “back” means that the light signal reaches later in the optical path.

[0073] The first polarization rotation unit 201 is configured to receive the horizontal polarized light and change the polarization state of the received horizontal polarized light, i.e., convert the horizontal polarized light into vertical polarized light, and output the vertical polarized light.

[0074] As can be seen from the foregoing, the photonic integrated chip has the excellent adaptability to the vertical polarized light output by the first polarization rotation unit 201, the direction of the light field is consistent with the direction of the PN junction 14, the coincidence degree of the light field and the PN junction depletion region is good, the modulation efficiency is greatly improved, and the coupling loss of the photonic integrated chip is reduced.

[0075] Further, the photonic integrated chip further comprises a second polarization rotation unit 202 located at the output end of the electro-optical modulator 100.

[0076] The second polarization rotation unit 202 is configured to receive the modulated vertical polarized light and change the polarization state of the received vertical polarized light, i.e., convert the vertical polarized light into horizontal polarized light, and output the horizontal polarized light.

[0077] In this way, the first polarization rotation unit 201, the electro-optical modulator 100 and the second polarization rotation unit 202 are sequentially arranged along the optical path, so that the vertical polarized light is transmitted in the electro-optical modulator 100, thereby greatly reducing the nonlinear loss caused by the transmission of light on the ridge waveguide.

[0078] Further, the embodiment also provides an optical module, which comprises a shell, a circuit board and the photonic integrated chip, i.e., comprises the electro-optical modulator 100.

[0079] The shell forms an accommodating cavity inside to accommodate at least the photonic integrated chip and the circuit board. The shell forms an optical port, which can be used to connect the optical module with an external optical fiber. The optical signal emitted by the optical assembly is output to the external optical fiber at the optical port, realizing the optical signal emission function of the optical module.

[0080] In addition, the optical module can further comprise an optical emission unit, a focusing lens, a first isolator, a mode spot conversion unit, a second isolator, a coupling lens, an optical fiber, etc.

[0081] For example, the optical emission unit, the focusing lens, the first isolator and the mode spot conversion unit are sequentially arranged in the optical path before the photonic integrated chip (for example, in the optical path before the first polarization rotation unit 201 in FIG. 3), and the second isolator, the coupling lens and the optical fiber are sequentially arranged in the optical path after the photonic integrated chip (for example, in the optical path after the second polarization rotation unit 202 in FIG. 3).

[0082] In operation of the photonic integrated chip, the light emitting unit emits horizontally polarized light, which sequentially passes through the focusing lens, the first isolator, the mode field conversion unit, and then enters the first polarization rotation unit 201; the first polarization rotation unit 201 converts the horizontally polarized light into vertically polarized light; then, the vertically polarized light enters the electro-optical modulator 100, the beam splitter 101 splits the vertically polarized light into two paths, and the two paths of the vertically polarized light are modulated via the two modulation arms of the electro-optical modulator respectively, and then the two paths of the modulated vertically polarized light are combined into one path of the vertically polarized light by the beam combiner 102 to serve as the output light of the electro-optical modulator 100; then, the output vertically polarized light is converted into horizontally polarized light by the second polarization rotation unit 202; then, the horizontally polarized light sequentially passes through the second isolator, the coupling lens, and the optical fiber to realize rear emission.

[0083] The light emitting unit can be a semiconductor laser, specifically a distributed feedback laser (DFB-LD), and can also be implemented as other light emitters known in the art.

[0084] In an embodiment, the optical module can be a light transmitter (TOSA) having only a light transmitting function, or a transceiver having both a light transmitting function and a light receiving function.

[0085] In summary, the embodiment has at least the following beneficial effects: compared with the conventional flat structure of the ridge portion 11, by increasing the etching depth of the flat plate portions 12a and 12b, the light signal can work in the vertically polarized light (TM) mode in the electro-optical modulator 100, so that the light field direction is consistent with the direction of the PN junction 14, the coincidence degree of the light field and the depletion region of the PN junction 14 is good, and the modulation efficiency of the electro-optical modulator 100 is improved.

[0086] Embodiment 2

[0087] Referring to FIG. 4, the embodiment provides an electro-optical modulator, and provides a photonic integrated chip and an optical module having the electro-optical modulator.

[0088] The embodiment is basically the same as the foregoing embodiment 1, and the difference is that a step portion 17a is additionally provided between the flat plate portion 12a and the contact portion 13a, and a step portion 17b is additionally provided between the flat plate portion 12b and the contact portion 13b. In addition to this, the other contents of the embodiment are the same as those of embodiment 1, and only the above difference will be introduced below, and the other same technical contents can be referred to embodiment 1, which will not be described here.

[0089] Specifically, in the foregoing embodiment 1, the lateral end of the flat plate part 12a is connected with the contact part 13a, and the lateral end of the flat plate part 12b is connected with the contact part 13b. Different from the foregoing embodiment 1, in the present embodiment, the modulation arm 10 further comprises step parts 17a and 17b.

[0090] Specifically, the step part 17a is connected with the lateral end of the flat plate part 12a and is away from the ridge part 11, that is, the step part 17a and the ridge part 11 are separated at the lateral ends of the flat plate part 12a, and the height h1 of the step part 17a is greater than the height h of the flat plate part 12a.

[0091] Similarly, the step part 17b is connected with the lateral end of the flat plate part 12b and is away from the ridge part 11, that is, the step part 17b and the ridge part 11 are separated at the lateral ends of the flat plate part 12b, and the height h1 of the step part 17b is greater than the height h of the flat plate part 12b.

[0092] Thus, while ensuring that the deep etching obtains the flat plate parts 12a and 12b, compared with the embodiment 1, in the present embodiment, by arranging the step parts 17a and 17b with greater height at the ends of the flat plate parts 12a and 12b away from the ridge part 11, the connection areas (i.e. the channels for electrical connection) on both sides of the ridge part 11 are formed by the flat plate parts 12a and 12b and the step parts 17a and 17b, so that the electrical resistance of the modulation arm 10 is greatly reduced by the step parts 17a and 17b, and the bandwidth of the electro-optical modulator is improved.

[0093] Herein, similar to the foregoing embodiment 1, in the present application, the height of the step part 17a refers to the dimension h1 of the P-type region 15 constituting the step part 17a in the first direction, and the height of the step part 17b refers to the dimension h1 of the N-type region 16 constituting the step part 17b in the first direction.

[0094] Herein, the height of the step part 17a and the height of the step part 17b can be arranged to be the same, for example, as shown in the figure, denoted by the same symbol h1; and in the present application, the height of the step part 17a and the height of the step part 17b can also be arranged to be different.

[0095] Correspondingly, different from the foregoing embodiment 1, in the present embodiment, the contact part 13a of the modulation arm 10 is connected with the lateral end of the step part 17a and is away from the ridge part 11; and the contact part 13b of the modulation arm 10 is connected with the lateral end of the step part 17b and is away from the ridge part 11.

[0096] That is, in the foregoing embodiment 1, the flat plate parts 12a and 12b are directly connected with the contact parts 13a and 13b, respectively. In the present embodiment, the step parts 17a and 17b are respectively arranged between the flat plate parts 12a and 12b and the contact parts 13a and 13b.

[0097] Further, in the present embodiment, the step portion 17a is provided as a single-step structure, i.e. it has a single constant height h1; similarly, the step portion 17b is provided as a single-step structure, i.e. it has a single constant height h1. Preferably, the height h1 of the step portions 17a, 12b is ≤ 2H / 3. The step portions 17a, 17b of the present application are not limited to a single-step structure, e.g. in a variant embodiment, the step portions 17a, 17b can be provided as a multi-step structure, e.g. each comprising a first step having a single constant height h1 and a second or more steps having a height less than h1.

[0098] Preferably, on one lateral side of the ridge portion 11, the height increases successively from the flat portion 12a to the contact portion 13a, i.e. the height of the contact portion 13a is greater than the height h1 of the step portion 17a, the height h1 of the step portion 17a is greater than the height h of the flat portion 12a, and when the step portion 17a is a multi-step structure, the height of each step also increases successively towards the contact portion 13a. Similarly, on the other lateral side of the ridge portion 11, the height increases successively from the flat portion 12b to the contact portion 13b, i.e. the height of the contact portion 13b is greater than the height h1 of the step portion 17b, the height h1 of the step portion 17b is greater than the height h of the flat portion 12b, and when the step portion 17b is a multi-step structure, the height of each step also increases successively towards the contact portion 13b.

[0099] Further, in the present embodiment, the flat portion 12a and the ridge portion 11 intersect at a P-type lightly doped region 151, the step portion 17a and the contact portion 13a intersect at a P-type heavily doped region 153, and the step portion 17a and the flat portion 12a can intersect at a P-type moderately doped region 152 as shown in Fig. 3, or can vary to intersect at the P-type lightly doped region 151, or can vary to intersect at the P-type heavily doped region 153.

[0100] Similarly, the flat portion 12b and the ridge portion 11 intersect at an N-type lightly doped region 161, the step portion 17b and the contact portion 13b intersect at an N-type heavily doped region 163, and the step portion 17b and the flat portion 12b can intersect at an N-type moderately doped region 162 as shown in Fig. 3, or can vary to intersect at the N-type lightly doped region 161, or can vary to intersect at the N-type heavily doped region 163.

[0101] In the embodiment, the shape of the modulation arm 10 is set to be mirror-symmetrical with the PN junction 14. Correspondingly, in the ridge portion 11, the lateral width of the N-type lightly doped region 161 of the N-type region 16 and the lateral width of the P-type lightly doped region 151 of the P-type region 15 are the same, and the height of the N-type lightly doped region 161 and the height of the P-type lightly doped region 151 are the same; the height of the flat plate portion 12a and the flat plate portion 12b is the same, and the width is also the same; the height of the step portion 17a and the step portion 17b is the same, and the width is also the same; the height of the contact portion 13a and the contact portion 13b is the same, and the width is also the same.

[0102] The embodiment 2 further has the beneficial effect compared with the previous embodiment 1: by setting the step portions 17a, 17b with greater height at the end of the flat plate portions 12a, 12b away from the ridge portion 11, the flat plate portions 12a, 12b and the step portions 17a, 17b jointly constitute the connecting region on both sides of the ridge portion 11 (i.e. constitute the channel for electrical connection), thereby greatly reducing the resistance of the modulation arm 10 by using the step portions 17a, 17b, and improving the bandwidth of the electro-optical modulator.

[0103] Embodiment 3

[0104] Referring to FIG. 5, the embodiment provides an electro-optical modulator, and provides a photonic integrated chip and an optical module with the electro-optical modulator.

[0105] The electro-optical modulator of the embodiment can be completely the same as the electro-optical modulator introduced in the previous embodiment 1 or embodiment 2, and the difference between the embodiment and the previous embodiment 1 or embodiment 2 is only that the photonic integrated chip is a two-way or more optical output and the corresponding optical path structure. The differences are introduced below.

[0106] In the embodiment, the photonic integrated chip includes a total beam splitter 203, which is used to divide the received optical signal into n-way optical signals.

[0107] Wherein, n is set to be a positive integer greater than or equal to 2, such as 2, 3, 4, 8, 12, etc.

[0108] In the embodiment, corresponding to the n-way optical signals, the photonic integrated chip further includes a first polarization rotation unit 201, an electro-optical modulator 100 and a second polarization rotation unit 202 in each of the n-way optical signals, so that each optical signal output by the total beam splitter 203 is first converted into vertical polarized light by the first polarization rotation unit 201 in the optical path, then modulated by the electro-optical modulator 100 in the optical path, and then converted into horizontal polarized light by the second polarization rotation unit 202 in the optical path, and then continues to output.

[0109] The optical module comprises, in sequence in the incident light path of the total beam splitter 203, an optical emission unit, a focusing lens, a first isolator, a mode spot conversion unit, the optical emission unit emitting horizontally polarized light, the light signal passing through the focusing lens, the first isolator, and the mode spot conversion unit in turn, and then entering the total beam splitter 203 and being divided into n light signals by the total beam splitter 203.

[0110] In addition, corresponding to the n light signals, the optical module further comprises a second isolator, a coupling lens, an optical fiber, and the like in each of the n light signals, after the second polarization rotation unit 202 in each light signal converts the vertically polarized light into horizontally polarized light, the horizontally polarized light passes through the second isolator, the coupling lens, and the optical fiber in the light signal in turn and is emitted backward. Thus, the photonic integrated chip realizes n light signal output.

[0111] The other technical contents of this embodiment are the same as those of the previous embodiments 1 or 2, and will not be described again.

[0112] Embodiment 4

[0113] Referring to FIG. 6, this embodiment provides an electro-optical modulator, and provides a photonic integrated chip and an optical module having the electro-optical modulator.

[0114] This embodiment is basically the same as the previously described embodiment 3, and the difference between this embodiment and the previous embodiment 3 is only that the position of the total beam splitter 203 in the light path and the number of the first polarization rotation units 201 adapted thereto. The differences will be described below.

[0115] In the previous embodiment 3, the total beam splitter 203 is located in the light path before the n first polarization rotation units 201, in other words, the n light signals divided by the total beam splitter 203 each have a corresponding first polarization rotation unit 201.

[0116] In this embodiment, the total beam splitter 203 is located in the light path after the first polarization rotation unit 201, that is, in the light path of the first polarization rotation unit 201. In this way, a horizontally polarized light is first converted into a vertically polarized light by the first polarization rotation unit 201, the total beam splitter 203 is used to receive the vertically polarized light from the first polarization rotation unit 201 and divide the vertically polarized light into n vertically polarized lights, and each of the vertically polarized lights output by the total beam splitter 203 is output to the electro-optical modulator 100 in the corresponding light path for modulation, and then converted into a horizontally polarized light by the second polarization rotation unit 202 in the corresponding light path and then continuously output backward.

[0117] The other technical contents of this embodiment are the same as those of the previous embodiment 3, and will not be described again.

[0118] In summary, the beneficial effects of the present application are that, compared with the conventional flat structure ridge type part 11, the electro-optical modulator 100 of the present application can make the optical signal work in the vertical polarization light (TM) mode in the electro-optical modulator 100 by increasing the etching depth of the flat plate part 12a, 12b, that is, the electro-optical modulator can be applied to modulate the vertical polarization light, so that the light field direction is consistent with the direction of the PN junction 14, the coincidence degree of the light field and the PN junction depletion region is good, and the modulation efficiency of the electro-optical modulator 100 is improved.

[0119] It should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

[0120] The series of detailed descriptions listed above are only specific descriptions of the feasible implementation modes of the present application, and they are not used to limit the protection scope of the present application, and any equivalent implementation modes or changes made without departing from the spirit of the present application should be included in the protection scope of the present application.

Claims

1. An electro-optical modulator comprising a pair of modulation arms, each of the modulation arms comprising a ridge portion and a slab portion connected to both lateral sides of the ridge portion; the modulation arms having a P-type region and an N-type region in lateral side-by-side arrangement, and a longitudinal PN junction formed in the ridge portion; characterized in that, a height of the slab portion is within 1 / 3 of a height of the ridge portion; and a lateral width of the ridge portion is 0.8-1.5 times a height of the ridge portion.

2. The electro-optic modulator of claim 1, wherein, a lateral width of the ridge portion is 150-550 nm, and a height of the ridge portion is 250-400 nm.

3. The electro-optic modulator of claim 1, wherein, a lateral width of the slab portion is not less than 100 nm.

4. The electro-optic modulator of claim 1, wherein, the modulation arms further comprise a step portion connected to lateral ends of the slab portion and away from the ridge portion, the step portion having a height greater than that of the slab portion.

5. The electro-optic modulator of claim 4, wherein, the step portion is provided in a single-step structure or a multi-step structure, and the height of the step portion is within 2 / 3 of the height of the ridge portion.

6. The electro-optic modulator of claim 4, wherein, the modulation arms further comprise a contact portion connected to lateral ends of the step portion and away from the ridge portion; the electro-optical modulator further comprises two electrodes, one of the electrodes being electrically connected to one of the contact portions, and the other of the electrodes being electrically connected to the other of the contact portions.

7. The electro-optic modulator of claim 6, wherein, from the slab portion to the contact portion, a height on either lateral side of the ridge portion increases in sequence.

8. The electro-optic modulator of claim 6, wherein, the P-type region and the N-type region each have a lightly-doped region, a medium-doped region, and a heavily-doped region arranged in sequence away from the PN junction in the lateral direction; the slab portion and the ridge portion meet at the lightly-doped region, the slab portion and the step portion meet at the lightly-doped region, the medium-doped region, or the heavily-doped region, and the step portion and the contact portion meet at the heavily-doped region.

9. The electro-optic modulator of claim 1, wherein, the P-type region and the N-type region are arranged to be mirror-symmetric with respect to the PN junction.

10. The electro-optic modulator of claim 1, wherein, the electro-optical modulator further comprises a beam splitter and a beam combiner, and the pair of modulation arms are connected in parallel between the beam splitter and the beam combiner.

11. A photonic integrated chip, characterized in that the photonic integrated chip comprises a first polarization rotation unit and the electro-optical modulator according to any one of claims 1-10 arranged in sequence along an optical path; the first polarization rotation unit is configured to change a received horizontally-polarized light into a vertically-polarized light; the electro-optical modulator is configured to receive the vertically-polarized light and modulate the vertically-polarized light.

12. The photonic integrated chip according to claim 11, wherein, the photonic integrated chip further comprises a second polarization rotation unit at an output end of the electro-optical modulator, the second polarization rotation unit being configured to receive the modulated vertically-polarized light and change the vertically-polarized light into the horizontally-polarized light.

13. The photonic integrated chip of claim 11, wherein, the photonic integrated chip further comprises: a total beam splitter located in an incident light path of the first polarization rotation unit, or in an optical path between the first polarization rotation unit and the electro-optical modulator.

14. An optical module characterized by comprising: the optical module comprises an optical emission unit and the photonic integrated chip according to any one of claims 11-13, the first polarization rotation unit is configured to change horizontally-polarized light emitted by the optical emission unit into vertically-polarized light, and the electro-optical modulator is configured to receive the vertically-polarized light and modulate the vertically-polarized light.

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