Photonic chip with one or two Mach-Zehnder modulators

Description

FIELD OF THE INVENTION

[0001] The present invention relates to the field of photonics and more particularly to integrated photonic chips.

[0002] In particular, the invention relates to a photonic chip provided with a Mach Zehnder modulator and for which the insertion losses are compensated by two optical amplifiers with semiconductor materials.

[0003] According to the present invention, the optical amplifiers with semiconductor materials are arranged in such a way as to limit the negative effects relating to the amplification of an intensity-modulated optical signal. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0004] There figure 1represents a Mach Zehnder 1 device known from the state of the art. The Mach Zehnder 1 device comprises in particular two modulation branches, called first branch 2 and second branch 3, connected at one end by an optical input 4 and at the other end by an optical output 5.

[0005] In particular, the two modulation branches 2 and 3 are arranged so that a light radiation injected at the optical input 4 is divided into a first radiation and a second radiation guided, respectively, by the first branch 2 and the second branch 3, and so that said first radiation and said second radiation are recombined at the optical output.

[0006] The device is also provided with two phase modulators, called first modulator 6 and second modulator 7, intended to impose a phase shift, respectively, on the first radiation and the second radiation before their recombination at the optical output 5. The modification of the phase of one and / or the other of the first and second radiation makes it possible in particular to modulate the intensity of the recombined radiation at the output of the Mach Zehnder device.

[0007] However, such a Mach Zehnder 1 device is subject to losses, and more particularly to losses linked to the losses of phase modulators 6 and 7, which reduce its performance.

[0008] Also, in order to overcome this problem, it is considered to add to the Mach Zehnder device a semiconductor optical amplifier ("Semiconductor Optical Amplifier" or "SOA" according to Anglo-Saxon terminology) in order to amplify the recombined radiation. In this regard, the document [1] cited at the end of the description as well as the document US9344196 disclose a Mach Zehnder device provided with a semiconductor optical amplifier arranged downstream of the optical output of said device.

[0009] However, this arrangement is not satisfactory. Indeed, and as indicated in document [2] cited at the end of the description, the optical gain G of an optical amplifier with semiconductor materials is not linear. More particularly, the optical gain G decreases when the optical power injected at the input of said amplifier increases so that the power delivered at the output of the optical amplifier with semiconductor materials cannot exceed a saturation power. This non-linear behavior thus gives rise to distortions of the intensity-modulated signal amplified by the SOA.Furthermore, by the 'amplitude / phase' coupling effect known and quantified by those skilled in the art by the 'Henry factor' in III-V SOAs semiconductor components or lasers, the strong variations in optical intensity give rise to phase variations, and consequently, also alter a signal modulated in intensity and phase, also distorting the phase modulation.

[0010] Thus, an aim of the present invention is to propose a photonic chip provided with at least one Mach Zehnder modulator whose optical signal can be amplified without imposing distortion of the modulated signal. BRIEF DESCRIPTION OF THE INVENTION

[0011] The aim of the invention is achieved by a photonic chip comprising: a support substrate provided with a front face; a waveguide layer resting on the front face; one or two Mach Zehnder modulators formed on and / or in the waveguide layer, each comprising two modulation branches, called first branch and second branch, the modulation branches being arranged between an optical input and an optical output, so that light radiation injected at the optical input is divided into a first radiation and a second radiation intended to be guided by the Mach Zehnder modulator(s), and are then recombined at the optical output, each modulation branch being configured to modulate the phase of light radiation that said modulation branch is capable of guiding; the photonic chip being remarkable in that it comprises at least two optical amplifiers with semiconductor materials arranged to separately amplify the first radiation and the second radiation before their recombination at the optical output.

[0012] According to one embodiment, each of the two modulation branches comprises a modulation section formed by a waveguide, called a modulation waveguide, and a modulation element, advantageously the modulation element comprises at least one electrode, the modulation element being configured to modulate the phase of radiation capable of being guided by the modulation waveguide, the second branch also comprising a phase shift module configured to impose a fixed phase shift on light radiation capable of being guided by said second branch.

[0013] According to one embodiment, the Mach Zehnder modulator(s) comprises a single Mach Zehnder modulator, the first branch and the second branch of the single Mach Zehnder modulator being connected, by one of their ends, by the optical input and, by the other of their ends, by the optical output so that the first radiation and the second radiation are guided, respectively, by the first branch and by the second branch.

[0014] According to one embodiment, the at least two optical amplifiers with semiconductor materials comprise a first amplifier and a second amplifier arranged respectively on the first branch and on the second branch, the first amplifier and the second amplifier being configured to amplify, respectively, the first radiation and the second radiation.

[0015] According to one embodiment, the semiconductor material amplifier of a modulation branch is arranged downstream of the modulation section of the modulation branch considered.

[0016] According to one embodiment, the semiconductor material amplifier of a modulation branch is arranged upstream of the modulation section of the modulation branch considered.

[0017] According to one embodiment, the Mach Zehnder modulator(s) comprises two Mach Zehnder modulators called, respectively, modulator I and modulator Q so that the photonic chip forms an IQ modulator, the first branch and the second branch of modulator I being connected, by one of their ends, by an intermediate optical input called input I, and, by the other of their ends, by an intermediate optical output called output I, the first branch and the second branch of modulator Q being connected, by one of their ends, by another intermediate optical input called input Q, and, by the other of their ends, by another intermediate optical output called output Q.

[0018] According to one embodiment, said photonic chip comprises a radiation splitter and a radiation combiner, the radiation splitter comprising two waveguides called, respectively, input guide I and input guide Q, the input guide I and the input guide Q connecting the optical input with, respectively, input I and input Q, so that the first radiation and the second radiation are injected at, respectively, input I and input Q, the radiation combiner comprising two waveguides called, respectively, output guide I and output guide Q, the output guide I and output guide Q connecting the optical output with, respectively, output I and output Q.

[0019] According to one embodiment, the at least two optical amplifiers with semiconductor materials comprise a first amplifier I, a second amplifier I, a first amplifier Q and a second amplifier Q, the first amplifier I, the second amplifier I are arranged respectively on the first branch and on the second branch of the modulator I, while the first amplifier Q and the second amplifier Q are arranged respectively on the first branch and on the second branch of the modulator Q.

[0020] According to one embodiment, the semiconductor optical amplifier of a modulation branch of a Mach Zehnder modulator is arranged between the modulation section of the modulation branch in question and the intermediate optical output of said Mach Zehnder modulator.

[0021] According to one embodiment, the semiconductor optical amplifier of a modulation branch of a Mach Zehnder modulator is arranged between the modulation section of the modulation branch in question and the intermediate optical input of said Mach Zehnder modulator.

[0022] According to one embodiment, the at least two optical amplifiers with semiconductor materials comprise an amplifier I and an amplifier Q carried, respectively, by the output guide I and the output guide Q.

[0023] According to one embodiment, said photonic chip further comprises another phase shift module configured to impose another fixed phase shift on a light radiation between the Q output and the optical output.

[0024] According to one embodiment, the modulation waveguide comprises silicon, advantageously doped silicon, even more advantageously a PN junction along the silicon waveguide.

[0025] According to one embodiment, the at least two optical amplifiers with semiconductor materials comprise a waveguide made of III-V semiconductor materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other characteristics and advantages of the invention will emerge from the detailed description which follows with reference to the appended figures in which: [ Fig. 1 ] There figure 1 is a schematic representation of a Mach Zehnder 1 device known from the state of the art; [ Fig.2 ] There figure 2 is a schematic representation of a Mach Zehnder device capable of being implemented within the framework of the present invention; [ Fig.3 ] There figure 3 is a schematic representation of a support substrate on one face of which the waveguide layer rests, and according to a section plane perpendicular to the front face; [ Fig.4 ] There figure 4is a schematic representation of a photonic chip according to a first variant of a first embodiment of the present invention, the photonic chip according to this first embodiment notably comprises a single Mach Zehnder modulator and two optical amplifiers with semiconductor materials; [ Fig.5 ] There Figure 5 is a schematic representation of a photonic chip according to a second variant of the first embodiment of the present invention, the photonic chip according to this first embodiment notably comprises a single Mach Zehnder modulator and two optical amplifiers with semiconductor materials; [ Fig.6 ] There figure 6is a schematic representation of a photonic chip according to a first variant of a second embodiment of the present invention, the photonic chip according to this second embodiment notably comprises two Mach Zehnder modulators and four optical amplifiers with semiconductor materials; [ Fig.7 ] There figure 7 is a schematic representation of a photonic chip according to a second variant of a second embodiment of the present invention, the photonic chip according to this second embodiment notably comprises two Mach Zehnder modulators and four optical amplifiers with semiconductor materials; [ Fig.8 ] There figure 8 represents the photonic chip of the figure 7 associated with an intermediate module; [ Fig.9 ] There figure 9is a schematic representation of a photonic chip according to a third embodiment of the present invention, the photonic chip according to this third embodiment notably comprises two Mach Zehnder modulators and two optical amplifiers with semiconductor materials. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention relates to a photonic chip, and more particularly to a photonic chip provided with one or two Mach Zehnder modulators formed on and / or in a layer, called a waveguide layer, resting on a front face of a support substrate.

[0028] According to the present invention, the Mach Zehnder modulator(s) are arranged between an optical input and an optical output, such that light radiation injected at the optical input is split into a first radiation and a second radiation intended to be guided by the Mach Zehnder modulator(s), and are then recombined at the optical output.

[0029] The photonic chip comprises at least two optical amplifiers made of semiconductor materials arranged to separately amplify the first radiation and the second radiation before their recombination at the optical output.

[0030] There figure 2 is a schematic representation of a Mach Zehnder 100 modulator that can be implemented within the framework of the present invention.

[0031] In particular, the Mach Zehnder modulator 100 may be formed on or in a layer, called a waveguide layer 200 resting on a front face 310 of a support substrate 300 ( figure 3 ).

[0032] The support substrate 300 may comprise any type of material, and more particularly a semiconductor material. In particular, the semiconductor material may comprise silicon, or a III-V semiconductor. Alternatively, the support substrate 300 may comprise a piezoelectric material and in particular lithium niobate (LiNbO 3 ).

[0033] The waveguide layer 200 may comprise a dielectric material, for example silicon dioxide.

[0034] According to the terms of the present invention, a Mach Zehnder modulator comprises two modulation branches called, respectively, first branch 101 and second branch 102.

[0035] The first branch 101 and the second branch 102 are connected, by one of their ends, by an intermediate optical input 103, and, by the other of their ends, by an intermediate optical output 104.

[0036] More particularly, the first branch 101 and the second branch 102 each comprise a waveguide called, respectively, first waveguide 101a and second waveguide 102a. The first branch 101 and the second branch 102 each comprise a modulation section called, respectively, first modulation section 105 and second modulation section 106.

[0037] The modulation section of a given modulation branch is configured to modulate the phase of a light radiation likely to be guided by the modulation branch considered.

[0038] A modulation section of a modulation branch may in particular comprise a section of the waveguide of said branch, called the modulation waveguide, and an electrode intended to impose an electrical potential on said modulation waveguide.

[0039] A modulation section is in particular configured so that an electrical potential imposed by the electrode on the modulation waveguide modifies the refractive index of the modulation waveguide in question. This index modification makes it possible to impose a phase shift on light radiation capable of being guided by the modulation section in question. In this regard, the modulation waveguide may comprise a doped silicon guide, and more particularly a silicon waveguide accommodating a PN junction. Such a waveguide has a refractive index capable of being modulated as a function of an electrical potential imposed on it. Document [3] cited at the end of the description provides an example thereof that a person skilled in the art may implement within the scope of the present invention. The invention is however not limited to these aspects alone, and a person skilled in the art may envisage other solutions.In particular, and by way of example, the first modulation waveguide 108 and the second modulation waveguide 110 may comprise a III-V semiconductor or even LiNbO 3 , for example transferred by bonding to the substrate.

[0040] Thus, the modulation waveguide and the electrode of the first modulation section 105, called, respectively, first modulation guide 108 and first electrode 109, make it possible to impose a phase modulation, called first phase shift, on a light radiation guided by the first section 101. This first phase shift is notably modulated by the electrical potential, called first potential, imposed by the first electrode 109.

[0041] Equivalently, the modulation waveguide and the electrode of the second modulation section 106, called, respectively, second modulation guide 110 and second electrode 111, make it possible to impose a phase modulation, called second phase shift, on a light radiation guided by the second panel 102. This second phase shift is notably modulated by the electrical potential, called second potential, imposed by the second electrode 111.

[0042] According to the present invention, the first potential and the second potential may be equal to, respectively, u(t) / 2 and -u(t) / 2. Under these conditions, the phase shift imposed by the first modulation section 105 and by the second modulation section 106 are equal to, respectively, Mu(t) / 2 and -Mu(t) / 2 (M is an efficiency factor of a modulator).

[0043] The second branch 102 may also comprise a phase shift module 107 configured to impose a fixed phase shift Φ on a light radiation capable of being guided by said second branch 102 in addition to the phase shift -Mu(t) / 2.

[0044] Thus, a light radiation, of intensity Pin, injected at the intermediate optical input 103 is divided into two radiations intended to be guided, respectively, by the first branch 101 and the second branch 102. The radiation guided by the first branch 101 undergoes a phase shift equal to Mu(t) / 2, while the radiation guided by the second branch 102 undergoes a phase shift equal to -Mu(t) / 2 + Φ. These two radiations guided by, respectively, the first branch 101 and the second branch 102, are then recombined at the intermediate optical output 104 to form an output radiation of intensity Pout.

[0045] For a fixed phase shift Φ equal to π / 2, Pout follows the following law: Pout = Pin / 2 + Pin / 2 ∗ sin M . u t

[0046] It is understood, without needing to be specified, that a modulation branch of a Mach Zehnder modulator according to the terms of the present invention forms an optical path without branching. In other words, light radiation injected at the intermediate optical input of a Mach Zehnder modulator undergoes only a single division.

[0047] The Mach Zehnder modulator 100 described above is integrated into a photonic chip 10 which is the subject of the present invention. More particularly, the photonic chip 10 according to the present invention comprises one or two Mach Zehnder modulators 100 whose modulation branches are arranged between an optical input 112 and an optical output 113 so that light radiation injected at the optical input is divided into a first radiation and a second radiation intended to be guided by the Mach Zehnder modulator(s) 100, and are then recombined at the optical output.

[0048] The photonic chip 10 comprises at least two optical amplifiers made of semiconductor materials arranged to separately amplify the first radiation and the second radiation before their recombination at the optical output.

[0049] There figure 4is a schematic representation of a photonic chip 10 according to a first variant of a first embodiment of the present invention and implementing a Mach Zehnder modulator 100 as described above.

[0050] In particular, the photonic chip 10, according to this first embodiment, comprises a single Mach Zehnder modulator 100 and for which the fixed phase shift Φ is equal to π / 2. In particular, the optical input 112 and the optical output 113 are merged, respectively, with the intermediate optical input 103 and the intermediate optical output 104. Thus, radiation injected, for example by a laser source 400, at the optical input 112 is divided into a first radiation and a second radiation. The first radiation is then guided in the first branch 101 to have a phase shift equal to Mu(t) / 2 imposed on it. Equivalently, the second radiation is guided in the second branch 102 and has a phase shift equal to -Mu(t) / 2 + π / 2 imposed on it.

[0051] The photonic chip 10 further comprises two optical amplifiers with semiconductor materials called, respectively, first amplifier 114 and second amplifier 115, which are substantially identical.

[0052] The first amplifier 114 is arranged on the first branch 101, while the second amplifier 115 is arranged on the second branch 102. The first amplifier 114 and the second amplifier 115 are thus arranged to amplify according to a gain G, respectively, the first radiation and the second radiation.

[0053] The integration of a semiconductor optical amplifier into a waveguide is described in document [1] cited at the end of the description. In particular, such a semiconductor optical amplifier may comprise a multi-quantum well formed of InGaAsP layers. More particularly, this semiconductor optical amplifier may form a hybrid waveguide coupled with the waveguide of the modulation branch. This coupling may involve a transition section, and in particular a tapered waveguide (tappered waveguide according to Anglo-Saxon terminology). More particularly, the coupling may be adiabatic as described in document [4] cited at the end of the description.

[0054] Furthermore, a semiconductor optical amplifier can be bonded or formed by epitaxy on a waveguide, and in particular a silicon waveguide.

[0055] According to the first variant, the semiconductor optical amplifier of a modulation branch is arranged downstream of the modulation section of the modulation branch in question. In other words, the first amplifier 114 is arranged between the first modulation section 105 and the intermediate optical output 103, while the second amplifier 115 is arranged between the second modulation section 106 and the intermediate optical output 104.

[0056] There Figure 5illustrates a second variant of the first embodiment of the present invention. According to this second variant, the semiconductor optical amplifier of a modulation branch is arranged upstream of the modulation section of the modulation branch in question. In other words, the first amplifier 114 is arranged between the intermediate optical input 103 and the first modulation section 105, while the second amplifier is arranged between the intermediate optical input 103 and the second modulation section 106.

[0057] The arrangement of the optical amplifiers with semiconductor materials according to this first embodiment makes it possible to amplify light radiation modulated in phase only, and not in intensity as described in the document [1] cited at the end of the description. In other words, this arrangement makes it possible to limit, or even prevent, the non-linearity effects of the optical amplifiers with semiconductor materials.

[0058] The present invention also relates to a second embodiment. In this regard, the figure 6 illustrates a first variant of the second embodiment.

[0059] The photonic chip according to this second embodiment comprises two Mach Zehnder 100 modulators called, respectively, I modulator 100a and Q modulator 100b identical so that the photonic chip 10 forms an IQ modulator.

[0060] The I 100a modulator and the Q 100b modulation essentially follow the architecture of the Mach Zehnder 100 modulator of the first variant of the first embodiment.

[0061] In particular, the first branch 101a and the second branch 102a of the modulator I 100a are connected, by one of their ends, by the intermediate optical input called input I 103a, and by the other of their ends, by the intermediate optical output, called output I 104a. In an equivalent manner, the first branch 101b and the second branch 102b of the modulator Q 100b are connected, by one of their ends, by the intermediate optical input called input Q 103b, and by the other of their ends, by the intermediate optical output, called output Q 104b.

[0062] The first branch 101a and the second branch 102a of the modulator I also comprise, respectively, the first modulation section 105a and the second modulation section 106a.

[0063] Equivalently, the first branch 101b and the second branch 102b of the Q modulator also comprise, respectively, the first modulation section 105b and second modulation section 106b.

[0064] The second branch 102a and the second branch 102b each comprise a phase shift module, called, respectively, module I 107a and module Q 107b. In particular, the module I 107a and the module Q 107b are configured to impose a phase shift Φ equal to π.

[0065] The photonic chip 10 further comprises four optical amplifiers with semiconductor materials called first amplifier I 114a, second amplifier I 115a, first amplifier Q 114b and second amplifier Q 115b. In particular, the first amplifier I 114a, the second amplifier I 115a are arranged respectively on the first branch 101a and on the second branch 102a of the modulator I 100a. Equivalently, the first amplifier Q 114b and the second amplifier Q 115b are arranged respectively on the first branch 101b and on the second branch 102b of the modulator Q 100b.

[0066] More particularly, according to the first variant of the second embodiment, the semiconductor optical amplifier of a modulation branch of a Mach Zehnder modulator is arranged between the modulation section of the modulation branch considered and the intermediate optical output of said Mach Zehnder modulator.

[0067] Thus, the first amplifier I 114a is arranged between the first modulation section 105a and the output I 104a.

[0068] The second amplifier I 115a is arranged between the second modulation section 106a and the output I 104a.

[0069] The first amplifier Q 114b is arranged between the first modulation section 105b and the output Q 104b.

[0070] The second amplifier Q 115b is arranged between the second modulation section 106b and the output Q 104b.

[0071] The photonic chip 10 includes a radiation splitter 116 and a radiation combiner 117.

[0072] In particular, the radiation splitter 116 comprises two waveguides called, respectively, input guide I 116a and input guide Q 116b. The input guide I 116a connects the optical input 112 with the input I 103a, of the modulator I 110a. Equivalently, the input guide Q 116b connects the optical input 112 with the input Q 103b, of the modulator I 110b.

[0073] The radiation combiner 117 comprises two waveguides called, respectively, output guide I 117a and output guide Q 117b. The output guide I 117a connects the optical output 113 with the output I 104a. The output guide Q 117b connects the optical output 113 with the output Q 104b, of the modulator Q 100b.

[0074] The photonic chip may comprise another phase shift module 118 configured to impose another fixed phase shift Φ' equal to π / 2 on a light radiation between the output Q 104b and the optical output 113.

[0075] Thus, a light radiation injected at the optical input 112, for example by the laser 400, is divided into two radiations called first radiation and second radiation injected at, respectively, the input I and the input Q. The first radiation is modulated by the modulator I, to form a first modulated radiation, while the second radiation is modulated by the modulator Q to form a second modulated radiation.

[0076] The radiation combiner 117 then combines the first modulated radiation and the second modulated radiation into an output radiation.

[0077] The arrangement of the optical amplifiers with semiconductor materials according to this first variant of the second embodiment makes it possible to amplify light radiation modulated in phase only, and not in intensity as described in the document [1] cited at the end of the description. In other words, this arrangement makes it possible to limit, or even prevent, the non-linearity effects of the optical amplifiers with semiconductor materials.

[0078] The second embodiment also includes a second variant illustrated in figure 7 which differs from the first variant in that the semiconductor optical amplifier of a modulation branch of a Mach Zehnder modulator is arranged between the modulation section of the modulation branch in question and the intermediate optical input of said Mach Zehnder modulator.

[0079] Thus, the first amplifier I 114a is arranged between the input I 103a and the first modulation section 105a.

[0080] The second amplifier I 115a is arranged between the input I 103a and the second modulation section 106a.

[0081] The first amplifier Q 114b is arranged between the input Q 103b and the first modulation section 105b.

[0082] The second amplifier Q 115b is arranged between the input Q 103b and the second modulation section 106b.

[0083] The arrangement relating to this second variant is particularly advantageous since the light radiation likely to be injected at the level of the optical input 112 has a reduced intensity.

[0084] In particular, an intermediate module 500 ( figure 8) can be interposed between the source 400 and the optical input 112. In particular, the intermediate module 500 comprises a first radiation divider 501, a second radiation divider 502, a local oscillator 503, and a TM modulator 504.

[0085] The first radiation splitter 501 is configured to split a light beam, emitted by the laser, into two first intermediate beams. One of these two beams is injected into the local oscillator 503, while the second oscillator receives the other of these two first intermediate beams. The latter is in turn split by the second radiation splitter 502 into two second intermediate beams. One of these two second intermediate beams is injected into the TM modulator 504, while the optical input 112 receives the other of these two second intermediate beams.

[0086] In this configuration, losses in the radiation splitters are significant. The implementation of four optical amplifiers with semiconductor materials is therefore particularly advantageous.

[0087] The arrangement of the optical amplifiers with semiconductor materials according to this second variant of the second embodiment makes it possible to amplify light radiation modulated in phase only, and not in intensity as described in the document [1] cited at the end of the description. In other words, this arrangement makes it possible to limit, or even prevent, the non-linearity effects of the optical amplifiers with semiconductor materials.

[0088] There figure 9 represents the photonic chip 10 according to a third embodiment of the present invention.

[0089] This third embodiment differs from the first variant of the second embodiment in that said chip only comprises two optical amplifiers with semiconductor materials called, respectively, amplifier I 114c and amplifier Q 115c, and carried, respectively, by the output guide I 117a and the output guide Q 117b.

[0090] This third embodiment is advantageous when the modulator I and the modulator Q are used solely as phase modulators to produce a so-called 'phase shift keying' constellation. According to this configuration, the light radiation, at the output I 104a and the output Q 104b, is not intensity modulated. Each of the two optical amplifiers made of semiconductor materials, called, respectively, amplifier I 114c and amplifier Q 115c, and carried, respectively, by the output guide I 117a and the output guide Q 117b, only amplify phase-modulated radiation.

[0091] Of course, the invention is not limited to the embodiments described and variant embodiments can be made without departing from the scope of the invention as defined by the claims. REFERENCES

[0092] [1] T. Hiraki et al., “Membrane InGaAsP Mach-Zehnder Modulator Integrated With Optical Amplifier on Si Platform” J. Lightwave Technol. 38, 3030-3036 (2020); [2] R. Bonk et al., “Linear semiconductor optical amplifiers for amplification of advanced modulation formats” Opt. Express 20, 9657-9672 (2012); [3] Reed, G et al., “Silicon optical modulators” Nature Photon 4, 518-526 (2010); [4] S. Menezo et al., “Back-Side-On-BOX heterogeneous laser integration for fully integrated photonic circuits on silicon” 45th European Conference on Optical Communication (ECOC 2019), 2019, pp. 1-3.

Claims

1. Photonic chip (10) comprising: - a support substrate (300) provided with a front face (310); - a waveguide layer (200) resting on the front face; - two single Mach-Zehnder modulators (100a, 100b), referred to respectively as modulator I (100a) and modulator Q (100b), so that the photonic chip forms an IQ modulator, the two Mach-Zehnder modulators being formed on and / or in the waveguide layer, each comprising two modulation branches, referred to as first branch (101a, 101b) and second branch (102a, 102b), arranged between an optical input (112) and an optical output (113) so that a light ray injected at the optical input (112) is split into a first ray and a second ray, intended to be modulated by, respectively, the modulator I (110a) and the modulator Q (100b), and are then recombined at the optical output (113), each of the two modulation branches of a Mach-Zehnder modulator comprises a modulation portion (105a, 105b, 106a, 106b) formed by a waveguide, referred to as a modulation waveguide, and a modulation element, the modulation element being designed to modulate the phase of a ray capable of being guided by the modulation waveguide, the second branch (102a, 102b) also comprising a phase-shift module (107a, 107b) designed to impose a fixed phase shift onto a light ray capable of being guided by said second branch (102a, 102b), the first branch (101a) and the second branch (102a) of the modulator I (100a) being connected, at one of the ends thereof, by an intermediate optical input, referred to as input I (103a), and, at the other of the ends thereof, by an intermediate optical output, referred to as output I (104a), the first branch (101b) and the second branch (102b) of the modulator Q (100b) being connected, at one of the ends thereof, by another intermediate optical input, referred to as input Q (103b), and, at the other of the ends thereof, by another intermediate optical output, referred to as output Q (104b); the photonic chip also comprises a ray splitter (116) and a ray combiner (117), the ray splitter comprising two waveguides, referred to respectively as input guide I (116a) and input guide Q (116b), the input guide I and the input guide Q connecting the optical input (112) with, respectively, the input I and the input Q, so that the first ray and the second ray are injected at, respectively, the input I and the input Q, the ray combiner comprising two waveguides, referred to respectively as output guide I and output guide Q, the output guide I (117a) and the output guide Q (117b) connecting an optical output (113) with, respectively, the output I and the output Q; characterized in that the photonic chip comprises two single semiconductor optical amplifiers (114c, 115c), referred to respectively as amplifier I and amplifier Q, carried, respectively, by the output guide I and the output guide Q.

2. Photonic chip according to claim 1, wherein said photonic chip further comprises another phase shift module designed to impose another fixed phase shift onto a light ray between the output Q and the optical output (113).

3. Photonic chip according to either claim 1 or claim 2, wherein the modulation waveguide comprises silicon, advantageously doped silicon, even more advantageously a PN junction along the waveguide made of silicon.

4. Photonic chip according to claim 3, wherein the at least two semiconductor optical amplifiers comprise a waveguide made of III-V semiconductor materials.

5. Photonic chip according to any of claims 1 to 4, wherein said photonic chip further comprises an intermediate module (500) interposed between a light ray source (400) and the optical input (112), the intermediate module (500) comprises a first ray splitter (501), a second ray splitter (502), a local oscillator (503) and a TM modulator (504).

6. Photonic chip according to claim 5, wherein the first ray splitter is designed to split a light ray, emitted by the source (400), into two first intermediate rays, one of these two rays being injected into the local oscillator 503 while the second ray splitter receives the other of these two first intermediate rays.

7. Photonic chip according to claim 6, wherein the second ray splitter is designed to split the other of these two first intermediate rays into a ray injected into the TM modulator (504) and a ray injected at the optical input 112.