Photonic chip capable of emitting at least one output emission, and optical components using such chips

Abstract

The invention relates to an integrated photonic chip (PIC) for generating at least one combined emission light, the integrated photonic chip (PIC) comprising at least two active combining devices (ACD1, ACD2) optically associated with a bank of lasers (LB) having different wavelengths, the bank being composed of at least two lasers (L1, L2) emitting a first emission light (l1, l2) and a second emission light (l'1, l'2) and configured on at least one optical output (OO) to combine the emission light received at its optical input to generate a combined emission light (l1+l'1, l2+l'2; l1+l2, l'1+l'2). The invention also relates to an optical component comprising such a photonic chip.

Description

[Technical Field]

[0001] The present invention relates to a photonic chip that has very particular application in the field of communications using wavelength division multiplexing, and also to optical components that use such a chip. [Background technology]

[0002] The increasing need for communication between computing and storage resources in data centers requires the implementation of communication channels used in wavelength division multiplexing (WDM) to handle high bit rates, potentially as high as 400 Gbit / s or even 800 Gbit / s.

[0003] Part of the solution to address this need is to implement high-power WDM sources. As described in the paper "WDM Source Based on High-Power, Efficient 1280-nm DFB Lasers for Terabit Interconnect Technologies" by B. Buckley in IEEE PHOTONICS TECHNOLOGY LETTERS, Vol. 30, No. 22, November 15, 2018, such sources comprise a bank of distributed feedback lasers with Bragg gratings distributed along the laser cavity. The lasers emit light at stepped wavelengths, typically spaced 100 GHz apart.

[0004] Each laser is formed of an optical cavity defined between two facets, one of which is substantially transparent and coated with an anti-reflection coating, and the other facet is essentially reflective. Light emitted by the laser on the side of the substantially transparent facet is propagated to an input port of a passive optical mixer. This mixer generates a plurality of emissions at its output ports, each combining the emissions provided at the input ports. The output emissions thus generated at these output ports arelight is multi-wavelength (in a spectral comb, each line of the comb is a component of the radiation emitted by a bank of lasers) light (corresponding to fiber network is connected to the optical fiber via

[0005] The fabrication of such lasers is delicate because the reflective facets of the optical cavity must be formed with high precision. Indeed, it is necessary to position the reflective facets with great precision relative to the laser's feedback Bragg grating, to within 50 nm, or more appropriately, within 20 nm, which cannot be systematically achieved with commonly used laser cleaving techniques. Consequently, the efficiency of this fabrication method is relatively low, on the order of 50%, resulting in the formation of malfunctioning lasers. This low efficiency is all the more problematic as it applies to each laser in a bank of lasers. As a result, the fabrication efficiency of this bank, when it contains N lasers, is equivalent to the Nth power of the fabrication efficiency of a single laser, which can be particularly low for high values ​​of N (typically 8 or greater).

[0006] It is also known that the wavelength of the emitted light emitted by a distributed feedback laser having such a reflective facet is poorly controlled due to inaccurate positioning of the reflective facet. light This results in variability in the spacing that exists between the spectral lines, but it is generally desirable for this spacing to be constant, for example 100 GHz.

[0007] Finally, significant losses (especially insertion losses) in passive optical mixers used to form output emissions affect the amount of power available in the optical fiber to which the mixers are coupled. light It is proposed to create lasers with a power of several hundred milliwatts each, so that each laser has a power of 10 mW. These losses tend to increase with the number of input / output ports on the optical mixer, becoming a problem when the number of lasers in the bank is large. In such mixers, the input emission lightIn order to utilize the full power budget, the number of input and output ports must necessarily be the same. Therefore, the solution proposed in the aforementioned document requires that the number of optical fibers be the same as the number of lasers in the bank, which may be a limitation in certain applications.

[0008] Object of the invention The aim of the present invention is to propose a solution to at least some of these problems. Summary of the Invention

[0009] To this end, the present invention proposes an integrated photonic chip for generating at least one coupled emission light, the integrated photonic chip comprising: a bank consisting of at least two lasers with different wavelengths, each laser comprising an optical cavity defined by two ends and emitting a first light emission and a second light emission respectively from the two ends; at least two active combining devices optically associated with the bank of lasers, each active combining device having at least a first optical input and a second optical input for receiving a portion of the first emitted light and the second emitted light, and configured to combine, at at least one optical output, the emitted light received at the optical inputs of each active combining device to generate a combined emitted light, the active combining devices further comprising control and measurement elements for controlling the combined emitted light generated at their optical outputs, the control and measurement elements comprising at least one pilot-controllable phase shifter and a photodetector; - a waveguide for direct propagation of the first emitted light and the second emitted light between the bank of lasers and the active coupling device; network , and is equipped with.

[0010] Other advantageous, non-limiting features of the invention, taken alone or in any technically feasible combination, are: The two lasers are phase-shifted lasers, the ends of which are separated by a feedback grating; the optical cavity of each phase-shift laser comprises a grating that induces a quarter-wave shift in the cavity; The lasers of the bank of lasers are at least partially waveguided network and a first portion comprising: The integrated photonic chip comprises at least one emission zone for at least one output emission light, and a waveguide network also propagates the coupled emission light between the active coupling device and at least one emission zone of the chip; Each active coupling device is associated with a phase-shifted laser of the bank of lasers, and a first emission of the phase-shifted laser light and second release light are guided towards the first and second optical inputs of the active combining devices, respectively, and a control element and a measurement element may be used such that each active combining device coherently combines the first emitted light and the second emitted light; The active combining device performs coherent combining; a combiner having two inputs respectively coupled to the first and second optical inputs and two optical outputs, a first of the outputs being coupled to the optical output; the control element includes at least one pilot-controllable phase shifter arranged optically upstream of at least one of the inputs of the combiner; the measuring element includes a photodetector positioned optically downstream of the second output of the combiner; each active coupling device is associated with two phase-shifted lasers of the bank of lasers, the emitted light of one of the two phase-shifted lasers is guided towards a first optical input and the emitted light of the other of the two phase-shifted lasers is guided towards a second optical input, and using control and measurement elements, each active coupling device controls the emitted light of the two lasers. light It is possible to spectrally combine The active combining device performs spectral combining, a first combiner and a second combiner, the first combiner having two inputs respectively coupled to the first optical input and the second optical input, the second combiner having two outputs, the first of which is coupled to the optical output, the two combiners being optically coupled to each other by two arms; a delay line disposed in one of the two arms; the control element includes at least one pilot-controllable phase shifter arranged optically upstream of the second combiner; the measuring element includes a photodetector positioned optically downstream of the second output of the second combiner; the active coupling device of the first photonic block is arranged on a first side of the bank of lasers and the active coupling device of the second photonic block is arranged on a second side of the bank of lasers opposite the first side; the bank of lasers comprises 2^n phase-shifted lasers associated with at least 2^n active coupling devices forming a first coupling stage, n being an integer greater than 1; the integrated photonic chip comprises at least a second coupling stage arranged downstream of the first coupling stage, the second coupling stage being formed from at least one secondary coupling device; the number of output emissions is less than or equal to the number of phase-shifted lasers; the at least one secondary combining device is selected from the list formed by an active coherent combining device, an active spectrum combining device, a passive power divider; -Waveguide network is associated with at least one coupler, e.g., an edge coupler, arranged in an emission zone of the output emission light, Phase-shifted lasers have graded emission wavelengths.

[0011] According to another aspect, the object of the present invention proposes an optical component comprising an integrated photonic chip as disclosed above and an integrated control circuit electrically connected to the control element and the measurement element of the active coupling device, the integrated control circuit being configured to control the output emission light generated on the optical output of the active coupling device. [Brief explanation of the drawings]

[0012] Other features and advantages of the present invention will become apparent from the following detailed description of the invention which refers to the accompanying drawings. [Figure 1] FIG. 1 is a block diagram of a first embodiment. [Figure 2] FIG. 2 is a block diagram of the active coupling device of FIG. 1. [Figure 3] 1 shows a first example of an integrated photonic chip and optical component according to a first embodiment; [Figure 4] FIG. 10 is a block diagram of a second embodiment. [Figure 5a] FIG. 5 is a block diagram of the active coupling device of FIG. [Figure 5b] FIG. 5 is a block diagram of the active coupling device of FIG. [Figure 6] 10 shows a second example of an integrated photonic chip according to the second embodiment. [Figure 7] 10 shows a third example of an integrated photonic chip that is a hybrid of the first and second embodiments. [Figure 8] 10 shows a fourth example of an integrated photonic chip that is a hybrid of the first and second embodiments. [Figure 9] 10 shows a fifth example of an integrated photonic chip that is a hybrid of the first and second embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0013] The various embodiments and examples that are the subject of the following description use a bank of phase-shifted lasers, in which the lasers generally have different wavelengths, for example, stepped wavelengths uniformly distributed in a determined frequency band. In the communications application using wavelength division multiplexing (WDM) presented in the introduction of this application, for example, various embodiments and examples herein can provide a bank formed of 8 or 16 phase-shifted lasers, whose emitted light has frequencies separated from one another by 50 GHz, 100 GHz, 200 GHz, or 400 GHz.

[0014] The lasers constituting the laser bank are advantageously so-called "phase-shift" lasers. These are distributed feedback lasers, i.e., lasers that use a Bragg grating to select the wavelength of the emitted light. This feedback grating is distributed along the optical cavity, which has two ends defined by the extent of the grating. Thus, according to the present invention, each phase-shift laser emits a first and a second emission, respectively, from the two ends of the optical cavity. The optical cavity of each laser is equipped with a grating that induces a quarter-wave shift, inserted entirely in the center of the cavity, to ensure that the laser emits only over a single wavelength.

[0015] The integrated photonic chip is obtained by assembling the lasers of the laser bank with a first part of the chip, the first part having therein at least the waveguides of the chip. networkThis assembly can be carried out, for example, by molecular bonding. Such a technique is described in particular in the publication T. Thiessen et al., "Back-Side-on-BOX Heterogeneous Integrated III-V-on-Silicon O-Band Distributed Feedback Lasers," Journal of Lightwave Technology, vol. 38, no. 11, pp. 3000-3006, 2020. This technique allows the formation of a back-side laser and the emission of light into the waveguides of the chip, without the need to first form facets by cleaving the material that forms the optical cavity. network This allows you to connect to

[0016] Phase-shifted lasers have the advantage of providing emission with a very well-controlled wavelength. Their manufacture is relatively easy, especially when implementing the assembly techniques described above, and, as mentioned in the introduction to this application, they do not suffer from the efficiency limitations of distributed feedback lasers, in which one of the facets is provided with a reflective coating. However, such laser configurations often produce two emissions, one at each end of the optical cavity. light and these emissions light The optical power of each of the (single emission generated by a distributed feedback laser with a reflective facet) light (less than half the optical power of the

[0017] The various presented embodiments improve this situation by proposing a different architecture of an integrated photonic chip for the purpose of combining together the emissions coming from a bank of lasers. Thus, an integrated photonic chip with N phase-shifted lasers (generating 2N emissions) can be coupled to M optical fibers, where M is less than or equal to N. Each optical fiber receives the combined emissions from the chip with an improved amount of power.

[0018] It should be noted that the use of a passive mixer associated with a photonic chip comprising a bank of N lasers of power P, with 2N emissions generated of power P / 2, will result in providing at the output of this mixer 2N combined emissions, each with a power of P / 4N (2N * (A 2N mixer will induce losses on the order of 1 / 2N.) Such power levels are not sufficient, especially when this number N is relatively large.

[0019] In a chip with multiple lasers, for optical routing reasons, it is advantageous to arrange the phase-shifted lasers on the chip so that their respective edges are aligned to define a first side of the laser bank from which a first emission is emitted and a second side of the laser bank from which a second emission is emitted. Various embodiments repeat this advantageous arrangement, but this is in no way a limitation of the invention. In general, the lasers forming the laser bank may be arranged in any suitable arrangement.

[0020] 1 shows a block diagram of a first embodiment of an integrated photonic chip PIC. The chip PIC comprises a bank of lasers LB, here formed for ease of explanation from two phase-shifted lasers L1, L2. In this embodiment, the two emissions emitted by the lasers L1, L2 are combined into a combined emission of increased power. light are coherently combined with each other to form

[0021] The first phase-shifted laser L1 emits a first beam from each of its ends. light l1 and second release light Similarly, the second phase-shifted laser L2 emits a first emission from each of its ends. light l2 and second emission light As already mentioned, the emissions generated by the first laser L1 and the second laser L2 are light and advantageously have different wavelengths.

[0022] The integrated photonic chip PIC of the block diagram of Fig. 1 comprises two active coupling devices ACD1, ACD2, which are shown in detail in Fig. 2. Each active coupling device ACD1, ACD2 is associated with a laser L1, L2 and performs coherent coupling of a first emitted light l1, l2 with a second emitted light l'1, l'2. Thus, two combined emitted lights l1+l'1, l2+l'2 are generated by the lasers L1, L2 and are guided into emission zones Z1, Z2 of the chip, which may be formed, for example, by edge couplers.

[0023] The integrated photonic chip PIC also includes waveguides for propagating the first and second emitted light between the bank LB of lasers and the active coupling devices ACD1, ACD2, and for propagating the coupled emitted light between these active coupling devices ACD1, ACD2 and the emission zones of the chips Z1, Z2. network Advantageously, the waveguide WG propagates the first and second emitted light directly between the bank LB of lasers and the active coupling devices ACD1, ACD2, i.e., these emitted light are not modified (e.g. modulated) during this propagation.

[0024] In all embodiments of the present invention, the coupling devices ACD1, ACD2 are said to be "active" because they comprise control and measurement elements that control the emissions emerging from the phase-shifted lasers L1, L2, and in particular the phase of these emissions, thereby enabling them to be combined in a fully controlled manner. The control and measurement elements comprise at least one pilot-controllable phase shifter and a photodetector. Due to the active nature of these devices, the coupling can be achieved with reduced losses of the order of 0.5 dB. These control and measurement elements, in particular the pilot-controllable phase shifter and the photodetector, are electrically connected to electrical contact pads of the integrated photonic chip PIC. An integrated control circuit CTRL_IC can be associated with the integrated photonic chip PIC and is electrically connected to the control and measurement elements of the active coupling devices ACD1, ACD2. The integrated control circuit CTRL_IC calibrates the control elements (e.g., pilot-controllable phase shifters) and adjusts the combined emissions generated at the optical outputs of the active coupling devices ACD1, ACD2 to the respective phases of these emissions. light is adapted to regulate the optical power delivered at one of these optical outputs to comply with a selected set point, in particular to ensure that all optical power is delivered at one of these optical outputs. For this purpose, the integrated control circuit receives measurements provided by the photodetector, which measurements enable the implementation of the optical control.

[0025] FIG. 2 shows a first active coupling device ACD1 of the first embodiment; it is understood that the second active coupling device ACD2 has the same architecture. The first active coupling device ACD1 has a first optical input O11 and a second optical input O11' for receiving the first emitted light l1 and the second emitted light l'1, respectively, from the first laser L1. The first active coupling device ACD1 also has an optical output OO for generating the emitted light l1+l'1 by coherently combining the emitted light received at the optical inputs O11 and O11'. Such combining is performed, for example, by a combiner CP implemented by a multimode interferometer or a Y-junction waveguide. The combiner CP has two inputs coupled to the first optical input O11 and the second optical input O11', respectively, and two outputs, the first of which is coupled to the optical output OO of the active coupling device ACD1.

[0026] To enable this coherent combining, the first active combining device ACD1 shown in Fig. 2 comprises two pilot-controllable phase shifters PS1, PS1' arranged optically upstream of the input of the combiner CP. These may be thermo-optical phase shifters. light The phase delay propagated to the active coupling device ACD1 is controllable by an electrical signal PS_ctrl generated by the control device CTRL_IC. Generally, the active coupling device ACD1 of this first embodiment comprises at least one pilot-controllable phase shifter, which is sufficient to enable coherent combining, but achieving the conditions enabling this combining may require a considerable amount of energy. For this reason, it is advantageously proposed to equip the active coupling device with two pilot-controllable phase shifters.

[0027] The first active combining device ACD1 shown in Figure 2 also comprises a photodetector PD optically downstream of the second output of the combiner CP, which photodetector generates an electrical signal TAP that is supplied to the control device CTRL_IC.

[0028] In operation, the control device CTRL_IC uses the control signal PS_ctrl to adjust the phases introduced by the phase shifters PS1, PS1' so that a maximum value of the optical power of the signal is combined at the output of the combiner CP propagating towards the optical output OO. To do this, the control device CTRL_IC uses the measurement signal provided by the photodetector PD to measure the optical power available on the other channels of the combiner and tries to minimize it. In other words, the control device CTRL_IC adjusts the phases introduced by the phase shifters PS1, PS1' using the control signal PS_ctrl so that a maximum value of the optical power of the signal is combined at the output of the combiner CP propagating towards the optical output OO. light l1 and second release light First release before binding l'1 light l1 and second release light Control is performed by adjusting the phase of l'1.

[0029] 3 shows a first example of an integrated photonic chip PIC and optical components according to this first embodiment of the invention. Here we again find a control device CTRL_IC electrically connected to the integrated photonic chip PIC by means of a bus BUS which groups together all the control and measurement signals PS_ctrl, TAP intended to control the active coupling devices ACD1 to ACDN of the chip PIC.

[0030] In this example, the integrated photonic chip PIC comprises N (e.g., 8, 16, or more) phase-shifted lasers. Each phase-shifted laser L1 to LN is associated with an active combining device ACD1 to ACDN, which coherently combines two emissions provided by each end of the optical cavity to form the laser.

[0031] The coupled emission light is guided in this example towards emission zones Z1 to Zn, where it is guided through the N optical fibers F1 to FN. networkThese emission zones Z1 to ZN may be equipped with coupling means, such as edge couplers or surface coupling gratings, to facilitate the injection of the coupled emission light into the fibers F1 to FN. Of course, other optical elements may be provided on the coupled emission light propagation path, either within the integrated photonic chip or outside the integrated photonic chip, to perform any desired transformation of the coupled emission light.

[0032] FIG. 4 shows a block diagram of a second embodiment of an integrated photonic chip PIC according to the invention.

[0033] For ease of description, the chip PIC in the block diagram of Figure 4 comprises a bank of lasers LB formed from two phase-shifted lasers L1, L2. The bank of lasers LB has all the characteristics of the bank shown in the first part of the detailed description. The two phase-shifted lasers L1, L2 emit, among other things, first light emissions l1, l'1 and second light emissions l2, l'2 having different wavelengths. In this embodiment, the emissions emitted by the two phase-shifted lasers L1, L2 are spectrally combined to form a combined multispectral radiation of increased power.

[0034] 4, the first emitted light l1 emitted by the first phase-shifted laser L1 and the first emitted light l2 emitted by the second phase-shifted laser L2 are both guided onto the optical inputs 0l1, 0l2 of the first active combining device ACD1, thereby resulting in a spectral combination of the two first emitted lights l1, l2 to form a first combined light l1+l2 in this embodiment. Similarly, the second emitted light l'1 emitted by the first phase-shifted laser L1 and the second emitted light l'2 emitted by the second phase-shifted laser L2 are both guided onto the optical inputs 0l1, 0l2 of the second active combining device ACD2 to form a combined light l'1+l'2. The active combining devices ACD1, ACD2 thus constitute a multiplexer or interleaver.

[0035] As in the first embodiment, the integrated photonic chip PIC of this second embodiment includes waveguides for propagating the first and second emitted light between the bank LB of lasers and the active coupling devices ACD1, ACD2, and for propagating the coupled emitted light between the active coupling devices ACD1, ACD2 and the emission zones Z1, Z2 of the chip. network Of course, as in the first embodiment, other optical elements may be added to the coupled emission light to perform any desired transformations on the coupled emission light. light It can be provided on the propagation path, within the integrated photonic chip PIC, or outside the integrated photonic chip.

[0036] The integrated photonic chip PIC may also be electrically connected to the control elements of the active coupling devices ACD1, ACD2 and associated with a control integrated circuit CTRL_IC similar to that presented in the first embodiment. The integrated control circuit CTRL_IC is thus configured to control the operation of the active coupling devices ACD1, ACD2 so that they perform the desired spectral coupling. To this end, the integrated control circuit CTRL_IC receives measurement signals TAP from the active coupling devices ACD1, ACD2 and generates control signals PS_ctrl directed to these devices.

[0037] 5a is a block diagram of the first active coupling device ACD of FIG. 4, and it is understood that the second active coupling device ACD2 has an identical architecture. In general, this active coupling device ACD of the second embodiment can be a Mach-Zehnder interferometer. More precisely, this first active coupling device ACD1 has a first optical input OL1 and a second optical input OL2 for receiving the first emitted light IL1 and IL2 of the two lasers L1 and L2, respectively. It also has an optical output OO for spectrally combining the emitted light received at the optical inputs OL1 and OL2 to generate a combined emitted light IL+IL. Such combining can be performed, for example, by two combiners CP1 and CP2 formed by a multimode interferometer or a Y-junction waveguide. The first combiner CP1 has two inputs respectively coupled to the first and second optical inputs Ol1 and Ol2, and two outputs respectively coupled to the two inputs of the second combiner CP2, which itself has two outputs, the first of which is coupled to the optical output OO of the active combining device ACD1.

[0038] To enable spectral combining without significant optical losses, the first active combining device ACD1 shown in FIG. 5a includes two pilot-controllable phase shifters PS1 and PS2 optically arranged between the two combiners CP1 and CP2. As in the first embodiment, the device can also include a single pilot-controllable phase shifter. The phase shift imparted to the emitted light by the phase shifters PS1 and PS2 is controllable by an electrical control signal PS_ctrl generated by the control device CTRL_IC. One of the two arms connecting the combiners CP1 and CP2 includes an additional waveguide section DL that forms a delay line. As is well known, the length of the additional waveguide section DL determines the transmission function of the active combining device, i.e., the spectral deviation that the first emitted light must have at the input of the device to be able to be coupled at the output. A detailed description of this device is given in particular in the publication "Wavelength Filters for Fiber Optics", edited by H. Venghaus, Springer Series in Optical Sciences, Vol. 123, Springer, pp. 381-432.

[0039] The first active combining device ACD1 shown in Fig. 5a also comprises a photodetector PD optically downstream of the second output of the second combiner CP2, which photodetector generates an electrical measurement signal TAP that is supplied to the control device CTRL_IC.

[0040] In operation, the control device CTRL_IC uses the control signal PS_ctrl to adjust the phase introduced by the phase shifters PS1, PS2 to emit light , the maximum optical power of which is coupled at the output of the coupler propagating towards the optical output OO. To do this, the control device CTRL_IC measures the optical power available on the other channels of the coupler using a measurement signal provided by the photodetector PD and thus tries to minimize the optical power.

[0041] Figure 5b shows an alternative block diagram to that shown in Figure 5a, in which the first active coupling device ACD is implemented in this case by a resonant ring. The resonant ring RR is arranged between two arms located between the optical input and optical output of the active coupling device ACD. A phase shifter PS is arranged on the resonant ring RR. One of the outputs is also equipped with a photodetector PD.

[0042] 6 shows a second example of an integrated photonic chip PIC according to a second embodiment of the present invention. For ease of reading, the control device CTRL_IC is omitted from the drawing, but such a device may be provided in electrical connection to the integrated photonic chip PIC, as presented in Example 1 of FIG. 3, to form a functional optical component.

[0043] The bank of lasers LB is located in the center of the integrated photonic chip PIC, between a first photonic block B1 and a second photonic block B2. These two blocks B1, B2 have identical configurations in this example, so only the architecture of the first block B1 is shown in detail. Of course, these two blocks do not have to be completely identical. Each block spectrally combines the emissions of the eight phase-shifted lasers of the bank of lasers LB in two emission zones Z1, Z2, thereby implementing the basic scheme of the second embodiment. light to join between them.

[0044] The phase-shifted lasers L1 to L8 of the bank LB of lasers have stepped wavelengths, with two lasers with successive indices Li and Li+1 separated by a spectral separation band of 100 GHz in this example. Of course, the value of this spectral separation band depends on the field of application, and the total emission light The available spectral bandwidth to accommodate and the number of phase-shifted lasers in the bank of lasers LB can be freely chosen.

[0045] Continuing with the description of FIG. 6 and the first photonic block B1, the latter comprises four active combining devices ACD1-ACD4, each associated with two first emissions of two different phase-shifted lasers. Four combined emissions are thus formed, each of which therefore has two spectral lines corresponding to the emission wavelengths of each of the original phase-shifted lasers. These four active combining devices ACD1-ACD4 are similar and form the first combining stage of the first block.

[0046] In the example of Figure 6, a second coupling stage is provided consisting of two active secondary coupling devices ACDa-ACDb. The coupled emissions are guided in pairs to the inputs of these two devices, which then combine these emissions to provide two coupled emissions. light are sequentially combined in pairs. light The first secondary device ACDa has four spectral lines corresponding to the emission wavelengths of the original phase-shifted lasers. More precisely, the first secondary device ACDa provides emission light l1+l2+l3+l4, which has the spectral components of the first four lasers L1-L4 to which it is optically coupled. Similarly, the second secondary device ACDb provides emission light l5+l6+l7+l8, which has the spectral components of the other four lasers L5-L8 in the bank to which it is optically coupled. Note that to facilitate this two-stage combining, the phase-shifted lasers L1-LN are associated with the first-stage active combining device in an interleaved manner, and two phase-shifted lasers associated with the same active combining device are shifted by 200 GHz. In this way, it is ensured that the spectral combining of the second stage of the first block B1 is performed for two emission lights with spectral lines separated by 100 GHz from each other.

[0047] Finally, the first photonic block in the example of Fig. 6 comprises, in the third stage, a power divider S constituting a device for passively combining the combined emissions exiting from the second stage. This passive combining device constitutes the third combining stage. Such a passive device allows for an easy (without active control) combination of the two combined emissions exiting from the second stage of the first photonic block B1, albeit at the expense of a relatively large optical loss of around 3.5 dB. This first block finally divides, in two emission zones Z1, Z2, the emissions exiting from the eight phase-shifted lasers L1 to L8 of the bank of lasers LB. light Spectral combining of two output emissions light Each output emission resulting from multiple couplings light It will be understood that the second photonic block B2 of the integrated photonic chip can have an architecture identical to that of the first photonic block B1, so that the integrated photonic chip PIC ultimately generates four output emissions, which are transmitted through four optical fibers (not shown). network can be linked to

[0048] More generally, it is understood that each photonic block B1, B2 can comprise multiple coupling stages, each stage consisting of at least one active or passive coupling device. Coupling devices present in stages of order two or higher are referred to in the present application as second-order coupling devices. Therefore, it is possible to create a particularly effective photonic chip (by prioritizing active coupling devices) and limit the number of output ports of the chip, i.e., each output emission has a relatively high optical power, regardless of the number of phase-shifted lasers. Therefore, an integrated photonic chip PIC is proposed, which has N phase-shifted lasers, each generating two output light beams, and this chip PIC can be effectively coupled to M optical fibers, where M is less than N (in the case of multiple coupling stages) or equal to N (in the case of a chip PIC with a single coupling stage).

[0049] Figure 7 shows a third example of an integrated photonic chip PIC, which is a hybrid of the first and second embodiments. To simplify the illustration, the control and measurement elements and associated signals for all active coupling devices are not shown, although they are of course present.

[0050] In this example, eight phase-shifted lasers L1 to L8 are associated with a first coupling stage formed from eight active coupling devices ACD1 to ACD8 according to the first embodiment. Each active coupling device therefore controls two emissions emerging from its associated phase-shifted laser. light Coherent combining is performed.

[0051] This first stage is connected to three other successive stages of secondary active combining devices that perform the spectral combining according to the second embodiment, i.e. network The second stage is composed of four secondary active coupling devices ACD1' to ACD4', the third stage is composed of two secondary active coupling devices ACDa and ACDb, and the fourth stage is composed of a single secondary active coupling device ACDc.

[0052] The integrated photonic chip of this third example uses only active coupling devices, which tends to reduce optical losses (at the expense of a slightly higher degree of control complexity). All optical power generated by the bank of lasers, except for losses, is transmitted to the single output emission of the chip PIC in a single emission zone Z1. light This power output will be available light transmits the spectral components of the eight phase-shifted lasers LS1 to LS8 of the bank LB.

[0053] Figure 8 shows a fourth example of an integrated photonic chip PIC, which hybridizes the first and second embodiments. It is a variant of the photonic chip of the third example of Figure 7, in which the secondary active coupling device of the fourth stage is replaced by a passive coupling device S, which may be a power divider. The optical power generated by the bank of lasers is distributed to the two output emitters of the chip PIC in two emission zones Z1, Z2. light It will be available at.

[0054] Figure 9 shows a fifth example of an integrated optical chip PIC, which is a hybrid of the first and second embodiments. It is a variant of the photonic chip PIC of the third and fourth examples of Figures 7 and 8, in which the secondary active coupling devices ACDa, ACDb, ACDc of the fourth and third stages are replaced by passive coupling devices S, such as power dividers. The optical power generated by the bank of lasers is distributed to the four output emitters of the chip PIC in four emission zones Z1 to Z4. light Note that this architecture requires the intersection of two waveguides in the zone indicated by an X in the figure, and this intersection introduces a loss of the order of 0.5 dB.

[0055] Naturally, the invention is not limited to the described embodiments, and variant embodiments can be added thereto without departing from the scope of the invention as defined by the claims.

[0056] Although the use of a bank of distributed feedback phase-shifted lasers has been shown to form a preferred type of laser in many applications due to the advantages described in the previous paragraphs of this application, the invention is by no means limited to this type of laser, and more generally applies to any bank formed by lasers, each laser comprising an optical cavity defined by two ends and emitting a first and second emission out of the two ends, respectively.

[0057] To reduce the number of contact pads on the integrated photonic chip PIC and to facilitate the routing of measurement signals, all conductive lines transmitting the measurement signals TAP of the active coupling devices ACD1-ACDN can be connected together. A single electrical measurement signal is thus available at a single pad on the chip PIC, representing the optical power available at all photodetectors of the active coupling devices of the chip PIC. A single line of the bus BUS transmits this measurement signal to a single input of the control device CTRL_IC. The latter implements a program for calibrating and / or controlling the control signal PS_ctrl of the phase shifters of each active coupling device ACD1-ACDN. The purpose of this calibration and / or control program is to minimize the value transmitted by a single measurement signal, for example during the start-up phase of the chip.

[0058] As an alternative to such a program, it may be proposed to equip the integrated photonic chip with a multi-way switch that is controllable by the control device CTRL_IC and that allows connecting the photodetector of the selected active coupling device to a single contact pad of the integrated photonic chip.

[0059] Furthermore, in various embodiments and examples, coupled release light Although it has been described and illustrated that the coupled emitted light is guided directly towards the emission zone of the integrated photonic chip, this feature is not essential. Therefore, other devices that block the propagation of these coupled emitted light, such as modulation network But the waveguide network It is possible to provide that the radiation is inserted before being propagated towards the emission zone of the tip by

[0060] More generally, an integrated photonic chip need not have an emission zone. An integrated photonic chip can, for example, constitute an integrated communication device between a computing device and a memory device, allowing data to be communicated between these two devices without the need to couple the chip to an optical fiber or propagate the output emission by free propagation. In this case, the coupled emission light In addition to the above-mentioned means for preparing light In general, therefore, the object of the invention is to generate at least one combined emission from a bank of lasers, which may be of the DFB, DBR (Distributed Bragg Reflector Laser) or DML (Directly Modulated Laser) type.

Claims

1. an integrated photonic chip (PIC) for generating at least one coupled emission light, comprising: a bank (LB) composed of at least two lasers (L1, L2) with different wavelengths, each laser comprising an optical cavity defined by two ends and emitting a first light emission (l1, l2) and a second light emission (l'1, l'2) respectively emitting from said two ends; at least two active coupling devices (ACD1, ACD2) optically associated with said bank (LB) of lasers, each active coupling device (ACD1, ACD2) having at least a first optical input (O11, O12) and a second optical input (O11', O12') for receiving, respectively, one of the first and second emitted light (l1, l2) and second emitted light (l'1, l'2) of one of said lasers (L1, L2), and at least one optical output (optical output, OO), configured to combine the emitted light received at the optical inputs (O11, O11'; O11, O12) of each active combining device (ACD1, ACD2) to generate combined emitted light (l1+l'1, l2+l'2; l1+l2, l'l+l'2), and the active combining devices (ACD1, ACD2) are configured to combine the emitted light received at the optical inputs (O11, O11'; O11, O12) of each active combining device (ACD1, ACD2) to generate combined emitted light (l1+l'1, l2+l'2; l1+l2, l'l+l'2), at least two active coupling devices further comprising control and measurement elements (PD, PS1, PS1'; PS2) for controlling the coupling of the emitted light and generating the combined emitted light (l1+l'1, l2+l'2; l1+l2, l'1+l'2) generated at the light output (OO), said control and measurement elements comprising at least one controllable phase shifter (PS1, PS1', PS2) and a photodetector (PD), an integrated photonic chip (PIC) comprising a waveguide network (WG) for direct propagation of the first emitted light and the second emitted light between the lasers (L1, L2) of the bank of lasers (LB) and the first optical inputs (O11, O12) and the second optical inputs (O11', O12') of the active coupling devices (ACD1, ACD2).

2. 2. The integrated photonic chip (PIC) of claim 1, wherein the two lasers (L1, L2) are phase-shifted lasers, the ends of which are separated by a feedback grating.

3. 3. An integrated photonic chip (PIC) according to claim 2, wherein the optical cavity of each phase-shift laser (L1, L2) comprises a grating that induces a quarter-wave shift in the cavity.

4. 2. An integrated photonic chip (PIC) according to claim 1, wherein the lasers (L1, L2) of the bank of lasers are assembled with a first part comprising at least partly the waveguide network (WG).

5. 2. The integrated photonic chip (PIC) of claim 1, comprising at least one emission zone (Z1-Z4) of at least one output emission light, said waveguide network (WG) also propagating said coupled emission light between said active coupling devices (ACD1, ACD2) of said chip and said at least one emission zone (Z1-Z4).

6. 2. The integrated photonic chip (PIC) of claim 1, wherein each active coupling device (ACD1, ACD2) is associated with a phase-shifted laser (L1, L2) of the bank of lasers (LB), and the first emitted light (l1, l2) and the second emitted light (l'1, l'2) of the phase-shifted laser (L1, L2) are guided towards the first optical input (Ol1) and the second optical input (Ol2) of the active coupling device (ACD1, ACD2), respectively, and the control element and the measurement element (PD, PS1, PS1') can be used so that each active coupling device (ACD1, ACD2) coherently combines the first emitted light (l1, l2) and the second emitted light (l'1, l'2).

7. said active combining devices (ACD1, ACD2) performing coherent combining; a combiner (CP) having two inputs respectively coupled to said first optical input (O11) and to said second optical input (O12) and two optical outputs, the first of which is coupled to said optical output (OO); said control element comprises at least one pilot-controllable phase shifter (PS1, PS1') arranged optically upstream of at least one of said inputs of said combiner (CP), An integrated photonic chip (PIC) according to claim 6, wherein said measurement element comprises a photodetector (PD) arranged optically downstream of the second output of said combiner (CP).

8. 2. The integrated photonic chip (PIC) of claim 1, wherein each active coupling device (ACD1, ACD2) is associated with two phase-shifted lasers (L1, L2) of the bank (LB) of lasers, and wherein the emission light (l1, l'1, l2, l'2) of one of the two phase-shifted lasers (L1, L2) is guided towards the first optical input (Ol1) and the emission light (l1, l'1, l2, l'2) of the other of the two phase-shifted lasers (L1, L2) is guided towards the second optical input (Ol2), and wherein the control and measurement elements (LS1, LS2, PD) can be used so that each active coupling device (ACD1, ACD2) spectrally combines the emission light emerging from the two lasers.

9. the active combining devices (ACD1, ACD2) perform spectral combining; a first combiner (CP1) and a second combiner (CP2), the first combiner having two inputs respectively coupled to the first optical input (O11) and the second optical input (O12), the second combiner having two outputs, the first of which is coupled to the optical output (OO), the two combiners being optically coupled to each other by two arms; a delay line (DL) arranged in one of the two arms, said control element comprises at least one pilot-controllable phase shifter (PS1, PS2) arranged optically upstream of said second combiner (CP2); The integrated photonic chip (PIC) of claim 8, wherein the measurement element comprises a photodetector (PD) arranged optically downstream of the second output of the second combiner (CP2).

10. 10. The integrated photonic chip (PIC) of claim 9, wherein the active coupling device (ACD1) of a first photonic block (B1) is arranged on a first side of the bank of lasers and the active coupling device (ACD2) of a second photonic block (B2) is arranged on a second side of the bank of lasers opposite the first side.

11. 2. The integrated photonic chip (PIC) of claim 1, wherein the bank of lasers comprises 2^n phase shift lasers (L1 to LN) associated with at least 2^n active coupling devices (ACD1 to ACDN) forming a first coupling stage, n being an integer greater than 1, and wherein the integrated photonic chip (PIC) comprises at least a second coupling stage arranged downstream of the first coupling stage, the second coupling stage being formed from at least one secondary coupling device.

12. The integrated photonic chip (PIC) of claim 11, wherein the number of output emissions is equal to or less than the number of said phase-shifted lasers (L1-LN).

13. 12. The integrated photonic chip (PIC) according to claim 11, wherein said at least one secondary combining device is selected from the list formed by an active coherent combining device, an active spectrum combining device, a passive power divider (S).

14. The integrated photonic chip (PIC) according to claim 11, wherein said waveguide network (WG) is associated with at least one coupler, for example an edge coupler.

15. 12. The integrated photonic chip (PIC) of claim 11, wherein the phase-shifted lasers (L1, L2) have graded emission wavelengths.

16. 16. An optical component comprising an integrated photonic chip (PIC) according to any one of claims 1 to 15 and a control integrated circuit (CTRL_IC) electrically connected to the control and measurement elements (PS1, PS1', PS2, PD) of the active coupling devices (ACD1, ACD2), wherein the integrated control circuit (CTRL_IC) is configured to control the output emission light generated on the optical output (OO) of the active coupling devices (ACD1, ACD2).

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