Integrated photonic emission circuit capable of operating over an extended temperature range

Abstract

The invention relates to an integrated photonic emission circuit (1) comprising a laser source (LS) for producing light radiation and including a grating defining an emission wavelength (Lbragg) and a first amplifying medium (A1) having a first photoluminescence wavelength (L1), and a semiconductor optical amplifier (SOA) comprising a second amplifying medium (A2) having a second photoluminescence wavelength (Lgain). According to the invention, the laser source (LS) and the optical amplifier (SOA) are configured such that, at a first temperature (T0), the emission wavelength (Lbragg) is closer to the first photoluminescence wavelength (L1) than to the second (Lgain), and, at a second temperature (T1), the emission wavelength (Lbragg) is closer to the second photoluminescence wavelength (Lgain) than to the first (L1). Figure to be published with the abstract: Fig. 2a

Description

Title of the invention: Integrated photonic emission circuit capable of operating over an extended temperature range. FIELD OF THE INVENTION

[0001] The present invention relates to an integrated photonic emission circuit. Such a circuit can find application in the field of telecommunications for the realization of a transmission component or in the field of sensors, for example for the realization of a LIDAR component. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Integrated photonic circuits are integrated circuits capable of generating, detecting, or manipulating light radiation. Like electronic integrated circuits, these circuits can incorporate multiple functional blocks, such as laser sources, switches, modulators, amplifiers, and power distributors, on a single substrate (for example, a silicon-based substrate), these blocks being connected to each other by waveguides.

[0003] An integrated photonic emission circuit is equipped with a light source, typically a laser source. In a manner well known per se (see, for example, EP2811593), such a source comprises an optical gain medium formed by a stack of layers of III-V materials constituting at least one heterojunction or so-called "active" region, for example, a plurality of quantum wells. This stack can be made from materials chosen from the following non-exhaustive list: InP, AsGa, InGaAlAs, InGaAsP, InAsP. The choice of materials composing this stack defines the photoluminescence wavelength of the gain medium. The gain medium is characterized by its amplification gain, which is a function of the wavelength.This function exhibits a peak at the so-called "photoluminescence" wavelength, and decreases on either side of this wavelength to define an amplification bandwidth whose width can typically be on the order of 30nm.

[0004] The amplifying medium is arranged, for example in a ribbon, opposite a portion of a waveguide, called the coupling portion, the waveguide being made, for example, of silicon. The flow of a current in this medium allows it to be electrically pumped in order to establish a hybrid optical mode in the amplifying medium and in the portion of the waveguide. The laser effect is obtained via a feedback structure that forms a resonant cavity. This structure can be implemented by a distributed reflector, for example a Bragg grating, arranged in the amplifying medium or in the waveguide. The Bragg grating defines the length of emission wave of the light radiation produced by the laser source. The hybrid optical mode that forms in the amplifying medium and in the coupling portion of the underlying waveguide tends to propagate in the waveguide.

[0005] Document EP3538937 proposes forming such a laser source (as well as the other active elements of the photonic integrated circuit) by "vignetting," that is, by transferring a block of III-V materials onto the coupling portion of a waveguide using a layer transfer technique. In other approaches, the block of III-V material layers forming the amplifying medium is produced by deposition, for example by epitaxial deposition, onto the coupling portion of the waveguide. This block of material is then processed, notably by etching, to form the electrical contacts on either side of the junction in order to create a functional laser diode. When it is desired to produce a plurality of active elements, for example, a plurality of laser sources, the IILV material block can also be structured to create a plurality of diodes arranged along a plurality of coupling portions of waveguides.This approach, the details and implementation variations of which can be found in the document EP3538937 cited above, is highly advantageous in that it simplifies the fabrication of integrated photonic emission circuits. This is particularly true when these circuits contain several active elements with amplifying media made of the same materials, by enabling the collective fabrication of these active elements.

[0006] To produce light radiation with satisfactory power, the emission wavelength of the light radiation (defined by the period of the Bragg grating) and the photoluminescence wavelength of the amplifying medium (defined by the nature of the materials defining the stacking) are chosen to correspond. At a minimum, the aim is to place the emission wavelength of the light radiation within the amplification bandwidth of the amplifying medium.

[0007] However, as US2011211603 points out, these wavelengths are affected by the operating temperature of the laser source. Thus, the emission wavelength of the light radiation, referred to as Lbragg in the remainder of this description, tends to increase with temperature, this increase being on the order of 0.1 nm / °C. The gain function and the peak gain of the amplifying medium, on the other hand, tend to increase much more significantly with temperature, on the order of 0.6 nm / °C.

[0008] Figure 1 represents, in a power-in-decibel (dB) / wavelength-in-nm coordinate system, the evolution of the gain Li of the amplifying medium and the emission wavelength Lbragg of a laser source, according to the prior art. It thus illustrates the phenomena appearing at three increasing temperatures T0, T1, T2 due to these differentiated drifts. It is noted first that the gain function of the amplifying medium G(TO),G(T1),G(T2), and in particular the amplitude of the gain peak, tends to decrease with temperature.

[0009] At a relatively low operating temperature T0, the emission wavelength Lbragg(T0) is located within the gain bandwidth of the amplifying medium, at a wavelength greater than the peak gain wavelength Li(TO). Although the gain is not at its maximum at this emission wavelength Lbragg(T0), this situation is not unfavorable, because at the relatively low temperature T0, the gain remains relatively high. The emission power of the emitted radiation can therefore be satisfactory.

[0010] At an intermediate operating temperature Tl, due to the drifts induced by the temperature rise on the gain function and the emission wavelength, the emission wavelength Lbragg(Tl) is located at a wavelength close to the wavelength Li(Tl) of the gain peak. This situation is favorable since the amplification provided is maximum or close to its maximum.

[0011] At a relatively high operating temperature T2, the emission wavelength Lbragg(T2) is located in the lower bandwidth of the gain of the amplifying medium, at a wavelength shorter than the peak gain wavelength Li(T2). This situation is unfavorable because it combines, on the one hand, a gain function weakened by the relatively high operating temperature, and on the other hand, the emission wavelength Lbragg(T2) is located in a portion far from the peak of this function. The power of the emitted light is therefore particularly low.

[0012] It is therefore understood that the laser source is capable of producing a light radiation having a satisfactory power, greater than a desired power threshold, in a limited operating temperature range, in the range [T0,Tl] in the example of [Fig.l].

[0013] To increase the power of the light radiation produced by the source, a semiconductor optical amplifier (often referred to in the field as a "Semiconductor optical amplifier" or SOA) can be added to the laser source, which is integrated into the photonic integrated circuit. An example of such an integrated circuit is described in US2013107900. This amplifier is arranged end-to-end (i.e., without an intermediate waveguide) with the laser source and, like the laser source, has an amplifying medium made from the same materials as the source.Although the semiconductor optical amplifier can somewhat extend the temperature range ensuring satisfactory operation of the laser source, by increasing the overall gain function applied to the light radiation produced, the photonic integrated circuit remains subject to the same temperature drift effects and therefore exhibits. the same limitations as those presented with reference to [Fig. 1].

[0014] It therefore remains desirable to extend the operating temperature range of integrated photonic emission circuits. SUBJECT OF THE INVENTION

[0015] One object of the invention is to provide at least a partial solution to this problem. More specifically, one objective of the invention is to provide an integrated photonic emission circuit exhibiting a wider operating temperature range than those of prior art integrated circuits. BRIEF DESCRIPTION OF THE INVENTION

[0016] To achieve this goal, the object of the invention proposes an integrated photonic emission circuit comprising: - a laser source to produce light radiation and comprising a grating defining an emission wavelength and a first amplifying medium presenting a first photoluminescence wavelength; - a semiconductor optical amplifier comprising a second amplifying medium, different from the first amplifying medium, and exhibiting a second photoluminescence wavelength; - at least one waveguide arranged between the laser source and the semiconductor optical amplifier to transmit the light radiation produced by the laser source to the semiconductor optical amplifier.

[0017] According to the invention, the laser source and the semiconductor optical amplifier are configured such that: i. at a first temperature, the emission wavelength is closer to the first photoluminescence wavelength than to the second photoluminescence wavelength, and; ii. at a second temperature, higher than the first temperature, the emission wavelength is closer to the second photoluminescence wavelength than to the first photoluminescence wavelength.

[0018] According to other advantageous and non-limiting features of the invention, taken alone or in any technically feasible combination: - the amplifying media of the laser source and the amplifying media of the amplifier are configured so that their respective photoluminescence wavelengths at the first temperature are separated by a wavelength difference less than or equal to their temperature drifts at the second temperature; - the first amplifying medium is chosen such that, over a temperature range between the first temperature and the second temperature, the difference between the emission wavelength and the first photoluminescence wavelength is less than half the bandwidth of the first amplifying medium; the integrated photonic emission circuit comprises a plurality of laser sources having a first amplifying medium of identical composition, a plurality of semiconductor optical amplifiers having a second amplifying medium of identical composition, and a plurality of waveguides respectively arranged between the laser sources and the semiconductor optical amplifiers to respectively transmit the light radiation produced by the laser sources to the semiconductor optical amplifiers; the integrated photonic emission circuit comprises a plurality of complementary semiconductor optical amplifiers having a second complementary amplifying medium of identical composition and having a complementary photoluminescence wavelength less than or equal, at the first temperature, to the second photoluminescence wavelength; the integrated photonic emission circuit comprises, optically downstream of the plurality of semiconductor optical amplifiers and the plurality of complementary semiconductor optical amplifiers, a plurality of optical switches, each optical switch being connected to a semiconductor optical amplifier and to a complementary semiconductor optical amplifier; the integrated photonic emission circuit comprises a plurality of laser sources and a plurality of semiconductor optical amplifiers, the laser sources and the semiconductor optical amplifiers having in pairs an amplifying medium of the same composition, and a plurality of waveguides respectively arranged between laser sources and semiconductor optical amplifiers having amplifying media of different composition; the integrated photonic emission circuit further includes a wavelength multiplexer disposed downstream of the plurality of semiconductor optical amplifiers and optically connected to the semiconductor optical amplifiers to produce multispectral light radiation; the integrated photonic emission circuit includes at least one additional optical device disposed between the laser source and the semiconductor optical amplifier; The additional optical device is a modulator or a switch. BRIEF DESCRIPTION OF THE FIGURES

[0019] Other features and advantages of the invention will become apparent from the detailed description of the invention which follows with reference to the accompanying figures in which:

[0020] [Fig.1]

[0021] Fig. 1 illustrates the phenomenon of thermal drift applying to an integrated photonic emission circuit and its impact on the power of the light radiation produced by this circuit;

[0022] [Fig.2a]

[0023] [Fig.2b]

[0024] Figures 2a, 2b represent, in top view, the schematic diagram of an integrated photonic emission circuit 1 according to various implementation modes;

[0025] [Fig.3]

[0026] Fig. 3 represents, in a power / wavelength coordinate system, the evolution of the gains of the amplifying media A1, A2 and of the emission wavelength Lbragg of the photonic circuit 1 configured according to the invention, with the operating temperature of the circuit;

[0027] [Fig.4]

[0028] Fig. 4 represents an integrated photonic emission circuit in a parallel configuration;

[0029] [Fig.5]

[0030] Fig. 5 represents another implementation method of an integrated photonic circuit in parallel configuration;

[0031] [Fig.6]

[0032] Fig. 6 illustrates the operation of the photonic circuit of Fig. 5;

[0033] [Fig.7]

[0034] Fig. 7 represents an example of another implementation method of a photonic circuit according to the invention, in series configuration. DETAILED DESCRIPTION OF THE INVENTION

[0035] Figure 2a shows, in top view, the schematic diagram of a circuit photonics 1 integrated emission according to an implementation mode. This photonic circuit 1 comprises, monolithically integrated on a substrate, a laser source LS, a semiconductor optical amplifier SOA (more simply referred to as "amplifier" in the remainder of this description), and a waveguide WG arranged between the laser source LS and the amplifier SOA.

[0036] The laser source LS comprises a first enhancing medium AL. This medium, as already presented in the introduction to this application, is formed of a stack of layers of IILV materials constituting at least one heterojunction, for example at based on InP, GaAs, InGaAlAs, InGaAsP, or InAsP. The first amplifying medium Al here takes the general form of a ribbon arranged at the edge of a first coupling portion of a waveguide WG1, for example made of silicon, in which an optical mode is established when a current flows through the first amplifying medium Al. For the sake of simplicity, the circuits, traces, and contacts allowing the injection of this current have been omitted from the schematic diagram in [Fig. 1].

[0037] The first amplifying medium Al exhibits a first photoluminescence wavelength Li that depends on the composition of an active region of this medium and its operating temperature. The active region can correspond to quantum wells based on IILV quaternary compounds (InGaAlAs, InGaAsP) or quantum dots based on InGaAs. The active region is sandwiched between a layer of N-type semiconductor material and a layer of P-type semiconductor material. These layers, typically based on InP or GaAs, allow a current to flow through the active region and electrically pump the amplifying medium to enable light generation.

[0038] The laser source also includes a grating G made in the first gain medium Al or in the first portion of the waveguide WG1, for example a Bragg grating. The grating G defines, in particular through its pitch, an emission wavelength Lbragg of the laser source LS.

[0039] Continuing the description of the schematic diagram in [Fig. 2a], the SOA amplifier comprises a second amplifying medium A2 exhibiting a second photoluminescence wavelength Lgain. This second amplifying medium A2 differs from the first amplifying medium Al, that is, it is composed of a stack of IILV materials with compositions different from those of the IILV materials composing the first amplifying medium AL. Consequently, the second photoluminescence wavelength Lgain differs from the first photoluminescence wavelength Lh

[0040] The second amplifying medium A2 also takes the general form of a pad arranged to the right of a second portion of waveguide WG2, extending between an input and an output of the amplifier, and in which the optical mode generated by the laser source LS propagates and is amplified.

[0041] The waveguide WG is arranged between the laser source LS and the input of the amplifier SOA to transmit the light radiation produced by this source LS to the amplifier SOA. It connects the first waveguide portion WG1 and the second waveguide portion WG2, which are therefore not arranged end to end as is the case in the photonic circuits of the prior art reported in the introduction to this application.

[0042] It is noted that the amplifying media A1,A2 of the laser source LS and of Since the SOA amplifiers are distinct from one another and made of materials with different compositions, they cannot be contiguous or constitute a single monolithic block of material. They are therefore separated by a distance d, this separation necessitating the presence of the waveguide WG to propagate the optical mode of the laser source LS to the SOA amplifier.

[0043] Of course, the integrated photonic circuit 1 for emission can have other elements which can, for example, be optically inserted between the laser source LS and the amplifier SOA, via a plurality of waveguides GW. Figure 2b shows a photonic circuit 1 of another embodiment, comprising a modulator MOD, optically connected by waveguides WG to the laser source LS and the amplifier SOA. Figures 2a and 2b also show an output waveguide WG3, optically connecting the output of the amplifier to, for example, a component enabling the coupling of the optical flux from the photonic circuit 1 to an optical fiber. Other coupling configurations of the photonic circuit 1 are alternatively possible, for example via a surface grating coupled to the output waveguide WG3.

[0044] Fig. 3 represents, in a power / wavelength coordinate system, the evolution of the gains of the amplifying media A1, A2 and of the emission wavelength Lbragg of the photonic circuit 1 configured according to the invention, with the operating temperature of the circuit.

[0045] At a first relatively low operating temperature T0, the emission wavelength Lbragg(T0) is positioned within the gain bandwidth of the first amplifying medium Al, at a wavelength greater than the peak gain wavelength Li(T0). This configuration is obtained by choosing the nature of the first amplifying medium Al and by defining the parameters of the laser source grating LS.

[0046] By way of example, at a first temperature corresponding to ambient temperature (20°C), the emission length Lbragg is 1330nm, and the photoluminescence wavelength Lidu of the first enhancing medium Al (the peak of the gain of this first medium) is chosen to correspond to 1315nm.

[0047] The bandwidth of the gain of the second amplifying medium A2 (shown in bold in [Fig. 3]) is configured, by choosing the nature of the materials constituting this medium, to be shifted from the bandwidth of the gain of the first amplifying medium A1 towards shorter wavelengths. However, it is advantageous to ensure that the SOA amplifier is "transparent," that is, that its gain at the emission wavelength Lbragg of the laser source LS is not less than ΔB at the first temperature T0.

[0048] By way of example, the photoluminescence wavelength Lgaindu second medium Amplifier A2 (the gain peak of this second medium) is chosen to correspond to 1300nm, which is 15nm lower than the photoluminescence wavelength of the first medium, Li

[0049] In this configuration at the first temperature T0, and as can be clearly seen in [Fig.3], the emission wavelength Lbragg is closer to the first photoluminescence wavelength Li than to the second photoluminescence wavelength Lgain.

[0050] The SOA amplifier contributes little to the amplification of the optical mode produced by the LS laser source. The optical mode produced by the LS laser source alone has sufficient power, exceeding a predetermined threshold, and requires little or no additional amplification.

[0051] When the operating temperature of the photonic circuit rises, the emission wavelength Lbragg and the first and second photoluminescence wavelengths Li, Lgain drift according to different dynamics.

[0052] Thus, at a second, relatively high operating temperature T1, the first and second photoluminescence wavelengths Lb Lgains are shifted towards longer wavelengths by a difference of approximately 0.6 nm per °C of temperature increase (i.e., the difference T1-T0). The gain functions of the first and second amplifying media A1, A2 are also of smaller amplitudes at the second temperature T1 than at the first T0. The emission wavelength Lbragg is, for its part, shifted towards longer wavelengths by a difference of approximately 0.1 nm per °C of temperature increase (T1-T0).

[0053] Continuing the example described above, and taking the second temperature T2 at 80°C, 60° higher than the first temperature T0 chosen at ambient temperature, the emission wavelength Lbragg (Tl) is shifted from 6nm to 1336nm, and the first and second photoluminescence wavelengths LH Lgains are shifted from 36nm to 135nm and 1336nm respectively.

[0054] Also, and due to this differential temperature drift dynamic, the emission wavelength Lbragg(Tl) is located, at the second operating temperature Tl, within the gain bandwidth of the first amplifying medium Al, at a wavelength shorter than the peak gain wavelength Li(Tl). This emission wavelength Lbragg(Tl) is also located within the gain bandwidth of the second amplifying medium A2.

[0055] At the second temperature Tl, the emission wavelength Lbragg is closer to the second photoluminescence wavelength Lgain than to the first photoluminescence wavelength Lp

[0056] Consequently, the SOA amplifier contributes to the amplification of the optical mode produced by the LS laser source. This amplification makes it possible to at least compensate for the lower gains of the amplifying media A1,A2 at relatively higher temperature Tl, in order to maintain an optical mode of sufficient power, above the determined threshold.

[0057] By differentiating the two amplifying media A1,A2 of the laser source LS and the amplifier SOA and by configuring them so that their photoluminescence wavelength Lb is shifted by a wavelength difference less than or equal to their temperature drift over a target temperature range [T0-T1], it is ensured that the optical mode produced by the laser source LS is sufficiently amplified, by the first amplification medium Al of the laser source LS and / or by the second amplification medium A2 of the amplifier SOA to maintain its power, over the extended target temperature range, above the determined threshold.

[0058] Advantageously, the first amplifying medium Al is chosen such that, over a temperature range between the first temperature T0 and the second temperature T1, the difference D between the emission wavelength Lbragg and the first photoluminescence wavelength Li is less than half the bandwidth BW / 2 of the first amplifying medium AL. In this way, it is ensured that over the entire temperature range [T0-T1], the laser source produces an optical mode with a power greater than a minimum power. The bandwidth BW of the first amplifying medium Al can, for example, be set at 3 dB, as is customary.

[0059] The first temperature T0 can be the ambient temperature and the second temperature can be 60°C, 80°C or 100°C depending on the operating range targeted by the photonic circuit 1.

[0060] The principles of the invention which have just been set out can be deployed in many modes of implementation.

[0061] Thus, [Fig. 4] represents an integrated photonic emission circuit 1 in a parallel configuration. This circuit comprises a plurality of identical laser sources LS. Each of these laser sources LS therefore includes a grating defining the same emission wavelength Lbragg. They also each include a first amplifying medium Al, these amplifying media Al all being of the same composition and thus defining the same first photoluminescence wavelength Lb. Advantageously, this medium is derived from a single monolithic block of IILV material formed at the edges of a plurality of first portions WG1 of waveguides, and structured to define the plurality of laser sources LS, as explained in the introduction to this application.

[0062] The photonic circuit 1 also comprises a plurality of SOA semiconductor optical amplifiers, each comprising a second amplifying medium A2 having the same composition and thus defining the same second photoluminescence wavelength Lgain. Advantageously, and as has been shown in In the case of the first amplifying medium Al, this second medium A2 is derived from a single monolithic block of III-V materials formed and structured at the right of a plurality of second portions WG2 of waveguide.

[0063] Finally, the photonic circuit 1 comprises a plurality of waveguides WG, WG' arranged between the laser sources LS and the semiconductor optical amplifiers SOA to respectively transmit the light radiation produced by the laser sources LS to the semiconductor optical amplifiers SOA. In the implementation shown in [Fig. 4], modulators MOD are also provided, respectively arranged between a laser source LS and an amplifier SOA to form an integrated transmission photonic circuit, but this element is entirely optional or could be replaced by an optical element providing another function.

[0064] The nature of the amplifying media A1, A2 and the emission wavelength Lbragg are chosen in accordance with what was presented in the description of the preceding figures: generally, at the first temperature T0, the emission wavelength Lbragg is closer to the first photoluminescence wavelength Li than to the second photoluminescence wavelength Lgain. At the second temperature T1, higher than the first temperature T0, the emission wavelength Lbragg is closer to the second photoluminescence wavelength Lgain than to the first photoluminescence wavelength Lb

[0065] Fig. 5 represents another implementation method of a photonic circuit 1 in parallel configuration.

[0066] The photonic circuit of this [Fig. 5] contains a plurality of laser sources LS and MOD modulators in the same configuration as that shown in [Fig. 4]. Each laser source LS is optically connected to an input of a MOD modulator via a waveguide WG. Output channels of the MOD modulators are respectively connected by other waveguides WG' to SOA semiconductor optical amplifiers having the same second amplifying medium A2. These elements are configured similarly to the implementation configuration of [Fig. 4].

[0067] Advantageously, the MOD modulators each have two outputs in opposite phase. They can thus be a Mach Zender silicon modulator. Alternatively, the modulators could be replaced by simple switches, also having two outputs onto which the energy of the light radiation propagating from their inputs is distributed.

[0068] In the case of the integrated circuit in [Fig. 5], the second output (not connected to the SOA semiconductor optical amplifier) ​​is optically connected, via the waveguides WG', to a plurality of optical amplifiers to Complementary SOA2 semiconductors. These complementary SOA2 amplifiers have the same complementary amplifying medium A2', which is different from the second amplifying medium A2. More precisely, the complementary amplifying medium A2' has a complementary photoluminescence wavelength Lgain2 less than or equal to the second photoluminescence wavelength Lgain at the first temperature TO.

[0069] As illustrated in [Fig.6], such a configuration of the photonic circuit makes it possible to extend the operating temperature range of the photonic circuit, the complementary SOA2 amplifiers ensuring the amplification of the optical modes when the temperature drift no longer allows the SOA amplifiers to ensure a sufficient gain.

[0070] Downstream of the SOA amplifiers and the SOA2 complementary amplifiers, a plurality of optical SW switches are provided to allow selection, from among the plurality of outputs of the SOA amplifiers and the SOA2 complementary amplifiers, and according to the effective operating temperature of the circuit 1, of the amplified radiation which is propagated by the output waveguides WG3 to the emission output of the integrated photonic circuit 1.

[0071] More specifically, at a relatively low temperature, the switches are operated to propagate the radiation from the SOA amplifiers towards the output waveguides WG3. At a relatively high temperature, the switches are operated to propagate the radiation from the complementary SOA2 amplifiers through the output waveguides WG3.

[0072] Fig. 7 represents yet another example of an implementation of a photonic circuit 1 according to the invention, this time in a so-called wavelength-multiplexed configuration.

[0073] In this configuration, a plurality of laser sources LS1-LS5 and a plurality of semiconductor optical amplifiers SOArSOA5 each comprise, in pairs, an amplifying medium A'i-A'5 of identical composition. In other words, an amplifying medium of a single composition A; is placed opposite a first portion of the waveguide of a laser source LS; and opposite a second portion of the waveguide of an amplifier SOA;. A plurality of waveguides WG, WG' are respectively arranged between laser sources LS; and optical amplifiers SOAi+i, the first amplifying medium A; of the laser source LS; being of a different composition from the second amplifying medium A'i+i of the optical amplifier SOAi+i, respectively, to transmit the light radiation produced by the laser sources LS; to the semiconductor optical amplifiers SOAi+i.

[0074] In the example shown, the photonic circuit comprises 5 types of amplifying media A'i-A'5, each derived from a block of IILV material formed and structured at right of a first waveguide portion of a laser source LS and a second waveguide portion of an amplifier SOA. The laser source LS is also equipped with a grating defining an emission wavelength Lbragg>i. The nature of the amplifying medium A' and the emission wavelength Lbragg>i are therefore chosen to allow the proper operation of the laser source LS and the amplifier SOA.

[0075] The circuit shown has a plurality of laser sources LS; each having a different emission wavelength Lbragg>i and a plurality of amplifiers SOA;. The emission wavelengths Lbragg>i.Lbragg>5 are stepped (1330 nm, 1310 nm, 1290 nm, 1245 nm, 1270 nm and 1225 nm as shown in [Fig.7]) to provide a plurality of light beams intended to be combined or multiplexed in wavelengths together and to form, at the output of the photonic circuit 1, a multi-wavelength beam. The materials of the A'i-A'5s enhancing media are chosen to also stagger their photoluminescence wavelength (1305 nm, 1285 nm, 1265 nm, 1245 nm and 1225 nm).

[0076] As can be seen in [Fig.7], waveguides WG allow optical coupling of a laser source LS comprising a first amplifying medium A'i presenting a first wavelength of photoluminescence to an amplifier SOA comprising a second amplifying medium A'i+i presenting a second wavelength of photoluminescence.

[0077] This chaining by the waveguides WG,WG' is repeated to couple a laser source LS; associated with a first amplifying medium A; to an amplifier SOAi+i associated with a second amplifying medium Ai+b different from the first.

[0078] It should be noted that in the chain shown in [Fig. 7], the first amplifier of the chain SOAb, associated with the amplifying medium designated A' in this figure, and the last laser source LS5, associated with the amplifying medium designated A'5 in the figure, are not used. Since these two elements are not used, they can therefore be omitted.

[0079] This wavelength-multiplexed implementation method has the advantage of limiting the number of amplification media of different compositions (panels) for the fabrication of the optical device by sharing their use. For example, 5 panels of different materials are needed to create the structure of [Fig. 7], these panels being structured to create the first and second amplification media associated with the 4 laser sources LS and the 4 amplifiers SOA, i.e., 8 amplification media.

[0080] Of course the invention is not limited to the modes of implementation described and alternative embodiments can be made without departing from the scope of the invention as defined by the claims.

Claims

Demands

1.

2. Integrated photonic emission circuit (1) comprising: a laser source (LS) to produce light radiation and comprising a grating defining an emission wavelength (Lbragg) and a first amplifying medium (Al) presenting a first photoluminescence wavelength (Li); a semiconductor optical amplifier (SOA) comprising a second amplifying medium (A2), distinct from the first amplifying medium (Al) and separated by a distance (d) from the first amplifying medium (Al), the semiconductor optical amplifier (SOA) having a second photoluminescence wavelength (Lgain); at least one waveguide (WG) disposed between the laser source (LS) and the semiconductor optical amplifier (SOA) to transmit the light radiation produced by the laser source (LS) to the semiconductor optical amplifier (SOA); the laser source (LS) and the semiconductor optical amplifier (SOA) being configured such that: at an initial temperature of 20°C (TO), the wavelength emission (Lbragg) is closer to the first photoluminescence wavelength (LJ) than to the second photoluminescence wavelength (Lgain), and; at a second temperature of 80°C (Tl), the wavelength emission wavelength (Lbragg) is closer to the second photoluminescence wavelength (Lgain) than to the first photoluminescence wavelength (Li). Integrated photonic emission circuit (1) according to claim 1 in in which the amplifying media (Al) of the laser source (LS) and the amplifying media (A2) of the amplifier (SOA) are configured so that their respective photoluminescence wavelengths (Lb Lgain) at the first temperature of 20°C (TO) are separated by a wavelength gap less than or equal to their temperature drifts at the second temperature (T2).

3. Integrated photonic emission circuit (1) according to any one of the preceding claims wherein the first amplifying medium (Al) is chosen such that, over a temperature range between the first temperature of 20°C (TO) and the second temperature (Tl), the gap (D) existing between the emission wavelength (Lbragg) and the first photoluminescence wavelength (LJ) is less than half the bandwidth of the first amplifying medium (Al).

4. Integrated photonic emission circuit (1) according to any one of the preceding claims comprising a plurality of laser sources (LS) having a first amplifying medium (Al) of identical composition, a plurality of semiconductor optical amplifiers (SOA) having a second amplifying medium (A2) of identical composition, and a plurality of waveguides respectively disposed between the laser sources (LS) and the semiconductor optical amplifiers (SOA) to respectively transmit the light radiation produced by the laser sources (LS) to the semiconductor optical amplifiers (SOA).

5. Integrated photonic emission circuit (1) according to claim 4 comprising a plurality of complementary semiconductor optical amplifiers (SOA2) having a second complementary amplifying medium (A2') of identical composition and having a complementary photoluminescence wavelength (Lgain2) less than or equal, at the first temperature of 20°C (TO), to the second photoluminescence wavelength (Lgain).

6. Integrated photonic emission circuit (1) according to the preceding claim comprising, optically downstream of the plurality of semiconductor optical amplifiers (SOA) and the plurality of complementary semiconductor optical amplifiers (SOA2), a plurality of optical switches (SW), each optical switch being connected to a semiconductor optical amplifier (SOA) and to a complementary semiconductor optical amplifier (SOA2).

7. An integrated photonic emission circuit (1) according to any one of claims 1 to 3 comprising a plurality of laser sources (LSi) and a plurality of semiconductor optical amplifiers (SOA), the laser sources and the semiconductor optical amplifiers (LSi, SOA) having in pairs an amplifying medium of the same composition, and a plurality of waveguides (WG, WG') respectively disposed between laser sources (LSi) and semiconductor optical amplifiers (SOAi+i) presenting amplifying media of different compositions.

8. Integrated photonic emission circuit (1) according to the preceding claim further comprising a wavelength multiplexer (MUX) disposed downstream of the plurality of semiconductor optical amplifiers (SOAi) and optically connected to the semiconductor optical amplifiers (SOA;) to produce multispectral light radiation.

9. Integrated photonic emission circuit (1) according to any one of the preceding claims, comprising at least one additional optical device disposed between the laser source (LS) and the semiconductor optical amplifier (SOA).

10. Integrated photonic emission circuit (1) according to the preceding claim wherein the additional optical device is a modulator (MOD) or a switch.

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