EP4244941A1

EP4244941A1 - Optoelectronic component

Info

Publication number: EP4244941A1
Application number: EP21811004.7A
Authority: EP
Inventors: Francesco MANEGATTI; Dorian SANCHEZ; Fabrice RAINERI
Original assignee: Centre National de la Recherche Scientifique CNRS; Universite Paris Saclay; Universite Paris Cite
Current assignee: Centre National de la Recherche Scientifique CNRS; Universite Paris Saclay; Universite Paris Cite
Priority date: 2020-11-16
Filing date: 2021-11-12
Publication date: 2023-09-20
Also published as: US20240022041A1; FR3116384A1; FR3116384B1; CN116601840A; WO2022101380A1

Abstract

The invention relates to an optoelectronic component (1) suitable for being integrated into an optoelectronic circuit, the component (1) comprising: - a III-V semiconductor membrane comprising: • a P-doped layer (2), referred to as the P layer, • an intrinsic layer (3) deposited on the P layer (2), and • an N-doped layer (4), referred to as the N layer, deposited on the intrinsic layer (3); - an asymmetrical photonic crystal waveguide (6, 16, 26), referred to as the PhC waveguide, formed in the membrane by a two-dimensional photonic crystal on one longitudinal side and by a face with total internal reflection on the other longitudinal side; - electrical contacts (10, 11) arranged respectively on either side of the PhC waveguide (6, 16, 26) in the plane of the membrane, adapted to inject electrical charge carriers into the PhC waveguide (6, 16, 26) laterally with respect to the membrane; the layers (2, 3, 4) being arranged such that the intrinsic and N layers (3, 4) only partially cover the P layer (2), forming a side face (5) extending perpendicularly from the surface of the P layer (2), a portion of the side face (5) forming the face with total internal reflection of the PhC waveguide; the PhC waveguide (6, 16, 26) being arranged to be evanescently coupled to a passive semiconductor waveguide (12) in at least one coupling region.

Description

Optoelectronic component

The present invention relates to an optoelectronic component adapted to be integrated into an optoelectronic circuit, as well as such an optoelectronic circuit.

The field of the invention is, without limitation, that of optoelectronic components for information and communication technologies.

State of the art

Optoelectronic components, such as laser sources, light amplifiers, photodetectors or optical modulators, are usually made in bulk crystals of III-V semiconductors. Apart from lasers of the VCSEL type ( Vertical cavity surface emitting laser ), their typical length is of the order of a millimeter. The electrical power required to drive these components is of the order of a few hundred mW. These characteristics limit the integration density of these components in an optoelectronic circuit.

Optoelectronic components including in particular "ribbon" type waveguide structures whose section is several µm² (~10µm²), with a length of about 1mm, integrated on silicon have been developed. Such components are described, for example, in documents [1-3]. By design, these devices offer only a reduced interaction of light with the gain or active material of the waveguide, thus limiting their energy efficiency.

To reduce the dimensions of these objects, it is possible to exploit nano-photonic concepts where the light is confined in volumes comparable to the order of magnitude of its wavelength in the semiconductor material of the guide. of wave. However, the fabrication of such optoelectronic components from nano-photonic concepts is very complex.

Examples of such nano-photonic components are described in documents [4] (laser), [5] (photodetector), [6] (modulator). The technology used is based on the production of a lateral PIN junction by implanting the dopants of the P and N layers. active material in the desired areas. High temperature annealing is also necessary for the activation of the implanted dopants. This has significant drawbacks. First, it is very difficult to integrate these components into optical circuits based on silicon photonics. Indeed, the heterogeneous integration of these components in a photonic circuit on Si, using a substrate transfer technology, is very complex, even impossible due to the difference in the coefficients of thermal expansion of the different materials involved during significant heating, especially during annealing. Secondly, the technology cannot be performed directly on microelectronic circuits because these cannot be exposed to temperatures exceeding 400°C.

The object of the present invention is to have an optoelectronic component making it possible to remedy at least one of the drawbacks described.

[1] A.W. Fang et al, Opt. Express 16, 4413 (2008)

[2] H. Park et al, IEEE Photon. Technology. Lett. 19, 223032 (2007)

[3] H.-W. Chen et al, Opt. Express 16, 20571-76 (2008)

[4] S. Matsuo et al, Opt. Express 20, 3773-80 (2012)

[5] K. Nozaki et al, Optica 3(5), 483-492 (2016)

[6] K. Nozaki et al, APL Photonics, 2, 056105 (2017)

An object of the present invention is to provide a very compact optoelectronic component which can be densely integrated into a photonic circuit.

Another object of the present invention is to provide an optoelectronic component with low power consumption.

Yet another object of the present invention is to provide an optoelectronic component whose manufacture is compatible with CMOS technology (acronym for " Complementary Metal oxide semiconductor ” ).

This objective is achieved with an optoelectronic component adapted to be integrated into an optoelectronic circuit, the component comprising:

a III-V semiconductor membrane comprising:

a P-doped layer, called the P layer,

an intrinsic layer deposited on the P layer, and

an N-doped layer, called N layer, deposited on the intrinsic layer;
an asymmetrical photonic crystal waveguide, called PC waveguide, formed in the membrane by a two-dimensional photonic crystal on one longitudinal side and by a total internal reflection face on the other longitudinal side;
electrical contacts arranged respectively on either side of the PC waveguide in the plane of the membrane, adapted to inject electrical charge carriers into the PC waveguide laterally relative to the membrane;

the layers being arranged such that the intrinsic and N layers cover the P layer only partially, forming a side face extending perpendicularly from the surface of the P layer, part of the side face forming the total reflection face internal PC waveguide; and

the PC waveguide being arranged to be evanescently coupled to a passive semiconductor waveguide in at least one coupling region.

The optoelectronic component according to the present invention constitutes a fundamental element for designing specific optoelectronic components that can be integrated into optoelectronic circuits. The invention thus proposes a unique design scheme of an optoelectronic component, presenting an active nano-photonic structure consisting of an asymmetric photonic crystal (PC) waveguide fabricated in a III-V semiconductor membrane. This active structure is coupled to a passive waveguide, adapted to propagate optical information in a photonic circuit.

Part of the side face, or ridge, represents the total internal reflection face of the CP waveguide.

The electromagnetic field present in the component according to the present invention is strongly confined in the CP waveguide, the component benefits from a lower energy consumption compared to the optoelectronic components of the state of the art.

The optoelectronic component according to the invention allows, thanks to the arrangement of the electrical contacts on either side of the waveguide CP in the plane of the membrane and thanks to the edge, a lateral injection of charge carriers, rather than vertically. The injection is thus carried out in the membrane in an efficient manner. Thus, the thickness of the membrane can be minimized (less than 500 nm), while avoiding absorption of the light guided in the CP waveguide by the metal of the contacts. The footprint of such a component on a photonic circuit can then be reduced while increasing the light confinement factor.

Thanks to its very compact structure, several of these optoelectronic components according to the invention can be densely integrated into photonic circuits. Also, the reduced size of the component makes it possible to increase the light-matter interaction. Indeed, the confinement factor defined as the spatial overlap of the light intensity with the light emitting material typically goes from a few percent in the case of a ribbon waveguide type configuration, to more than 15% in the case the invention. It is then possible to reduce the electrical power consumed. In addition, the reduction in size makes it possible to reduce the electrical capacity of the component, allowing an increase in its working frequency.

Optoelectronic components according to the invention allow in particular the co-integration of photonic and electronic circuits. Light can thus be used as an information carrier through electronic circuits, to be able to replace, at least in part, metallic interconnections with ultra-fast photonic links. The energy efficiency and speed of such co-integrated components are greatly improved compared to state-of-the-art circuits.

Subsequently, the region between the CP and the total reflection face, in the intrinsic, inner layer can be called "active region".

Their manufacture may be compatible with the CMOS technology used for the manufacture of electronic components and logic circuits. This is possible due to the fact that during manufacturing, only temperatures compatible with CMOS technology (< 400°C) are used.

Advantageously, a P contact can be arranged on the P layer facing the side face and an N contact can be arranged on the N layer adjacent to the photonic crystal, so that the contacts are arranged parallel to the guide. PC wave.

Thanks to this particular arrangement, the two electrical contacts are deposited on the same side of the optoelectronic component, on the other side with respect to the passive waveguide to which it can be coupled, thus facilitating the manufacture of the component.

This arrangement also allows efficient injection of charge carriers. When a potential is applied to the electrical contacts, electrons move in the N-doped layer through the CP region to reach the active region, and carriers from the P contact move in the P-doped layer to the active region. The resistivity of the CP region is higher than that of bulk material without CP. Thus, the carriers of the P contact have a shorter effective path than the electrons. The adjustment of the volume crossed by the charge carriers then makes it possible to attenuate the problem of unequal mobility between electrons and holes.

Alternatively, the P contact can also be arranged under the P layer. In this case, the P contact is between the P layer and the Si of the passive circuit.

According to one embodiment, the photonic crystal can be formed by holes extending through the N layer, the intrinsic layer and the P layer, the holes forming a two-dimensional periodic array.

Advantageously, the PC waveguide may include a gain region.

According to one example, the gain region can comprise quantum wells and/or quantum dots.

The presence of quantum wells and/or dots makes it possible to localize the process of stimulated emission, when light propagates in the CP waveguide and charge carriers are injected into the active region. This results in optical amplification.

According to one embodiment, the width of the waveguide CP can vary progressively in the at least one coupling region to the passive waveguide.

This makes it possible to gradually adjust the effective index of a guided mode in the CP waveguide, in order to reduce the difference in effective index between the CP waveguide and the passive waveguide. This results in efficient coupling without losses and reflections.

Advantageously, the respective distance of the electrical contacts from the CP waveguide can be inversely proportional to the width of the CP waveguide.

The electrical resistance thus remains constant along the waveguide CP.

According to one embodiment, the CP waveguide may include a slow light regime region, in which the photonic crystal includes a local disturbance.

Indeed, when the propagation speed of light in the CP waveguide is slowed down, the light-matter interaction time is increased. It is then possible to obtain the same amplification as a fast-rate amplifier but with an amplifier that is a factor of the group index shorter than a fast-rate amplifier.

According to one example, the waveguide PC can comprise two regions with a fast light regime, arranged respectively upstream and downstream of the region with a slow light regime.

The fast light regime regions contribute to the mode conversion of guided light in the passive waveguide to a guided mode in the slow light regime region.

According to an advantageous embodiment of the optoelectronic component according to the invention, a resonant optical cavity is formed in the waveguide PC by two mirror regions arranged in the direction of propagation of the waveguide PC and by a so-called region of apodization.

Advantageously, at least one geometric parameter of the photonic crystal in the apodization region can vary gradually between the center and the ends of the apodization region in the direction of propagation.

According to embodiments, the component may also comprise an additional one- or two-dimensional photonic crystal adjacent to the side face.

This additional photonic crystal can consist of one or two rows of additional holes, arranged on the side of the side face of the CP waveguide. One of these additional lines can in particular be made on the edge, which thus has half-holes.

The additional photonic crystal makes it possible in particular to reduce optical losses.

According to another aspect of the same invention, an optical amplifier is proposed, comprising an optoelectronic component according to the invention, configured to amplify light propagating in the PC waveguide when charge carriers are injected into it. this.

Such a nano-amplifier is an embodiment of a non-resonant optoelectronic component.

Other specific optoelectronic components can be designed based on the non-resonant component according to the invention, in particular optical modulators or photodetectors. The design is achieved by adjusting the composition of the III-V semiconductor membrane.

According to yet another aspect of the same invention, there is proposed a laser source comprising an optoelectronic component comprising a resonant cavity according to the invention, the cavity comprising a gain region, or an active material.

Such a laser source is an embodiment of a resonant optoelectronic component.

Other specific optoelectronic components can be designed based on the resonant component according to the invention, in particular optical modulators or photodetectors. The design is achieved by adjusting the composition of the III-V semiconductor membrane.

According to yet another aspect of the same invention, there is provided an optoelectronic circuit, comprising at least one of:

an optoelectronic component,
an amplifier, and
a laser source

according to the invention.

The applications of such a photonic circuit are in the fields of signal processing, telecommunications, artificial intelligence or even sensors.

Description of figures and embodiments

Other advantages and features will appear on examining the detailed description of non-limiting examples, and the accompanying drawings in which:

the shows two views of a non-limiting embodiment of an optoelectronic component according to the invention;
the schematically shows an example of a mode converter for an optoelectronic component according to one embodiment;
the shows examples of spatial distributions of radiative recombinations and a guided optical mode in a component as shown in the ;
the schematically represents an optoelectronic component according to one embodiment including a slow light guide;
the shows a detail view of an embodiment of a resonant optical cavity according to the invention;
the shows an example of longitudinal distribution of a Gaussian mode confined in an optical cavity as shown in the ;
the shows an example of a spatial distribution in the transverse direction of an optical mode confined in an optical cavity as shown in the ;
the shows examples of spatial distributions of a resonant mode and radiative recombinations in an optical cavity as shown in the ; and
the represents the intrinsic quality factor of a resonant mode and the average density of injected carriers participating in the gain as a function of the distance of the contact P with respect to the edge of the guide CP in an optical cavity such as represented on the .

It is understood that the embodiments which will be described below are in no way limiting. In particular, variants of the invention may be imagined comprising only a selection of characteristics described below isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention from the prior art. This selection includes at least one preferably functional feature without structural details, or with only part of the structural details if only this part is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art.

In particular, all the variants and all the embodiments described can be combined with each other if nothing prevents this combination from a technical point of view.

In the figures, the elements common to several figures may retain the same reference.

The shows two schematic representations (perspective view (a) and cross-sectional view (b), respectively) of a non-limiting embodiment of an optoelectronic component according to the invention.

The optoelectronic component 1, represented on the , comprises a semiconductor membrane, comprising a P-doped layer 2, called the P layer, an intrinsic layer 3 deposited on the P layer 2 and an N-doped layer 4, called the N layer, deposited on the intrinsic layer 3.

As illustrated on the (b), the P layer 2 is not completely covered by the intrinsic layer 3, but has an uncovered part 2a. The intrinsic layer 3 is completely covered by the N layer 4. Thus, the edges 3a, 4a of the intrinsic and N layers 3, 4 (and possibly also the edge 2a of part of the P layer) form a side face 5 s extending perpendicularly from the surface of the P layer 2.

An asymmetric photonic crystal (CP) waveguide 6 is fabricated in the optoelectronic component 1. As shown in the , the CP consists of a hexagonal arrangement of circular holes 7 etched in the membrane comprising the P, N and intrinsic layers, the holes 7 thus forming a two-dimensional periodic network. The confinement of the light in the asymmetric CP waveguide 6 is achieved on one longitudinal side by total internal reflection (TIR for “ total internal reflection”) on the lateral face 5 and on the other longitudinal side by the Two-dimensional CP. The waveguide CP 6 thus represents an asymmetric edge-type waveguide (“rib” according to English terminology).

On the (b), the horizontal arrow indicates the width of the CP waveguide.

The semiconductor membrane is in a III-V material. Depending on the intended operating wavelength of the component, the material can be based on GaN (visible range), GaS (near infrared) or InP (telecommunications range).

The operating wavelength of the optoelectronic component is adjusted by means of the geometric characteristics of the CP (period, diameter of the holes) and of the membrane (thickness) as well as the choice of III-V materials.

Electrically, the optoelectronic component 1 is a PIN-type heterojunction (P-doped region—intrinsic region—N-doped region). Electrical contacts P and N are placed parallel to the waveguide CP 6. As illustrated for the embodiment of the , the P contact 10 is arranged parallel to and facing the side face 5 on the P layer 2, and the N contact 11 is arranged parallel to the last row of holes 7 of the CP, on the opposite side of the side face 5. The P and N contacts 10, 11 are arranged in the immediate vicinity of the CP waveguide 6. By way of example, the distance between the edge and the P contact can be <1 μm, and the N contact can be arranged at about 2 to 4 µm from the center of the CP 6 waveguide.

The energization of the electrical contacts 10, 11 makes it possible to inject electrical charge carriers into the region of the CP waveguide 6.

The optoelectronic component 1 is coupled to a passive waveguide 12. In the embodiment shown, the component 1 is arranged above the passive waveguide 12 so that the CP waveguide 6 and passive waveguide 12 are evanescently coupled in at least one coupling region. The passive waveguide 12 is made of a silicon-based material (Si, SiN, SiO2, SiON, etc.). It can be part of a passive circuitry and allows the propagation of optical information.

The arrangement of the electrical contacts 10, 11 parallel to the waveguide CP 6, in the plane of the membrane, makes it possible to inject charge carriers laterally. This makes it possible in particular to minimize the thickness of the membrane and, consequently, to reduce the size of the component and to increase the confinement factor.

The asymmetrical arrangement of the CP waveguide and the P,N contacts takes into account the large difference in mobility between electrons and holes. The mobility is 80 times greater for the electrons. The radiative recombination of the charge carriers is well localized inside the waveguide CP 6. Indeed, the contact P is made as close as possible to the side face 5 of the waveguide CP 6, and the contact N is made on the opposite side of the holes 7 of the CP. The resistivity of the membrane provided with CP being greater than that of the membrane without CP, the holes take a much shorter path than the electrons to reach the CP 6 waveguide, making it possible to obtain an excellent spatial overlap between the guided optical mode and radiative recombinations.

The optoelectronic component 1 as shown in the can be adapted to obtain resonant or non-resonant optoelectronic components.

Examples of a non-resonant component and a resonant component will be described later.

An example of a non-resonant optoelectronic component according to an embodiment of the present invention is an optical nano-amplifier. In order to be able to use the guide CP as an amplifier, it includes a gain region. This gain region can be achieved, for example, by incorporating multiple quantum wells or quantum dots.

The nano-amplifier has technical characteristics similar to the optoelectronic component described with reference to the .

The amplifier also comprises several quantum wells or quantum boxes inserted into the III-V membrane at the level of the CP, in order to create a line defect there. Light amplification is achieved in this active material through the stimulated emission process. When an optical signal propagates in the CP waveguide and charge carriers are injected into the CP waveguide region at the same time, optical amplification of the signal results from the radiative recombinations of the charge carriers. For this, the wavelength of the optical signal and that of the radiation emitted during the recombinations must be identical. This wavelength is called the operating wavelength.

The geometric parameters of the CP can be chosen to obtain a single-mode waveguide at the operating wavelength. The geometric parameters can further be adjusted to modify the effective refractive index of the guided mode, the confinement factor and the gain.

According to one embodiment, the CP waveguide is coupled by evanescent waves to the passive waveguide (placed below on the (has)). To achieve this evanescent coupling, linear or adiabatic couplers can be used. The couplers progressively transform the optical mode confined in the passive guide into an optical mode confined in the CP guide. For this, the difference in the effective index between the two waveguides is gradually modified as a function of the propagation distance of the mode. Thus, the effective index difference is reduced in the coupling region.

The (top, (a)) schematically shows an example of arrangement of a linear coupler 100, or mode converter (to type according to the English terminology). The effective index of the guided mode in the CP waveguide 16 is adjusted by gradually modifying the width of the CP waveguide 16. The width of the passive waveguide 12 remains constant. Thanks to the variation of the width of the waveguide CP 16 in the region of the coupler 100, the effective index of the latter is progressively adapted.

The transfer of optical power from the passive waveguide 12 to the CP waveguide 16 thus obtained is illustrated in the bottom (b). The (b) shows a simulation of the conversion from a guided mode 22 in the passive waveguide 12 to a guided mode 29 in the CP waveguide 16. The spatial distributions of the electromagnetic fields in the respective guides are shown in the transverse direction at the inlet (e) and outlet (s) of the coupler 100, as well as in the longitudinal direction (l) over the entire length of the coupler 100.

To obtain optical amplification, the overlap between the intensity profile of the electromagnetic field propagating in the waveguide CP, the intensity profile of radiative recombination and the active material (wells and/or quantum dots) is optimized. To do this, the design of the CP waveguide must be optimized. The concentration of injected charge carriers giving rise to stimulated emission events can thus be maximized.

The shows the superimposition of the spatial distribution of the radiative recombination rate (curve 41) with that of the guided optical mode in the CP waveguide 16 (curve 42) for the component according to the embodiment of .

According to one embodiment, the nano-amplifier may comprise a region with a slow light regime. To do this, the geometric parameters of the CP are chosen so that the group low-speed guided mode is available at the desired wavelength.

According to an example, a local disturbance can be applied to the rows of holes of the CP closest to the edge of the component. This local disturbance may consist of a diameter slightly different from that of the other holes or a different relative position with respect to the network of holes. For example, the period of the holes can vary approximately between 1-30%. This has the effect of decreasing the group velocity dispersion in the CP guide and thus enlarging the operating wavelength band of the amplifier in the slow light regime.

In order to be able to couple a guided mode in the passive waveguide into the slow regime CP guide, it is necessary to operate the mode conversion in several steps. An example of a sequence of mode conversions is described below with reference to the .

A linear or adiabatic converter 31, as described with reference to , makes it possible to convert the guided mode in the passive silicon-based waveguide into the fundamental mode of the CP waveguide, represented by the converter. The fundamental mode of the CP waveguide is then coupled to that of a waveguide of the ridge type 32, in which the guiding of the light operates solely by total internal reflection. An additional structure 33 couples the mode of the ridge guide to the slow mode of the CP waveguide 34. The additional structure 33 consists of a CP waveguide in which the period of the CP is varied linearly in the direction of light propagation . The ridge 32 waveguide transfers the fundamental guided mode of the CP waveguide to the slow light band of the CP 34 waveguide.

The converters are arranged inversely at the output of the slow light CP waveguide 34.

By way of example, for a non-resonant optoelectronic component operating, for example as an optical amplifier, at a wavelength λ of 1550 nm, the period of the CP holes is approximately 260 nm, the holes have a radius of about 100 nm, the membrane has a thickness of about 450 nm, and the thickness of the passive waveguide circuitry is about 220 nm. The thickness of the membrane is given by λ/n, where n is the refractive index of the membrane of 3.34.

An example of a resonant optoelectronic component according to an embodiment of the present invention will be described below. This resonant optoelectronic component has technical characteristics similar to the optoelectronic component described with reference to the .

The resonant optoelectronic component further comprises a resonant optical cavity. The shows a detail view of an embodiment of such a resonant optical cavity.

The optical cavity 20, shown in the , is formed in the CP waveguide 26 by two mirror regions 27a, 27b arranged in the direction of propagation of the CP waveguide 26 and a so-called apodization region 28. The mirror regions and the apodization region are carried out in the CP. The also shows the side face 5 of the CP waveguide 26 and the P contact 10.

The optical cavity 20 can also comprise a region with an active material, possibly with wells and/or quantum dots, as described above for the nano-amplifier.

To produce the mirror regions 27a, 27b and the apodization region 28a, geometric parameters of the CP, such as the period or the radius of the holes 7, the width of the guide, etc., are modified and adapted.

In the mirror regions 27a, 27b, the photonic band gap located, in frequency, below the low group speed mode is exploited to confine the mode between the mirrors, by prohibiting the propagation of light beyond the mirror regions 27a, 27b, respectively.

In the apodization region 28, one or more of the geometric parameters of the CP, such as the width of the guide, the period or the diameter of the holes, are gradually modified from the ends towards the center of the cavity in the direction of propagation. . In particular, it is possible to obtain a resonant mode with a Gaussian spatial shape in this way.

The asymmetry of the CP waveguide generally results in a non-negligible amplitude transversely polarized magnetic (TM) of the electromagnetic field confined in the resonant mode, in addition to the main amplitude transversely polarized electrical (TE). The TM polarized amplitude is not reflected by the mirrors and is therefore not confined in the cavity, thus causing significant optical losses and preventing a high quality factor from being obtained.

To avoid or reduce these losses, the cavity may include one or two rows of additional holes on the side of the lateral face, or edge, of the waveguide CP. The cavity 20 according to the embodiment shown in the further comprises two rows of holes 17 additional to the component according to the embodiment of the . One of these lines is made astride edge 5, leaving half-holes in the side face, and the other of the lines is made in layer P close to edge 5.

Thus, the resonant optoelectronic component as described in relation to the makes it possible to obtain a cavity with a high quality factor (Q > 10 ⁵ ). An example of a longitudinal distribution 43 of a Gaussian mode confined in the cavity 20 is represented on the . The shows an example of a spatial distribution of an optical mode in the cavity 20 in the transverse direction. The illustrates the superposition of the spatial distributions of the optical mode (curve 51) and radiative recombinations (curve 52) in the cavity 20.

Such a resonant cavity, having a region with an active material, can in particular be used to produce a laser nano-diode.

By way of example, for a resonant optoelectronic component operating, for example as a laser source, at a wavelength λ of 1550 nm, the period of the CP holes is approximately 333 nm, the holes have a radius about 75 nm, and the thickness of the membrane is about 450 nm. The thickness of passive silicon-based circuitry is approximately 220 nm.

For the electrical injection of such a cavity, the following restrictions must be taken into account:

As illustrated on the , the optical mode also spreads slightly in the transverse direction in the area of the CP holes. The spatial overlap of the optical mode with the gain profile is reduced (see ). The net gain obtained can then be reduced.
The line(s) of additional holes can increase the resistivity of the P layer.

A sufficient electrical injection level can nevertheless be reached and thus make the structure laser by adjusting the distance of the electrical metallic contact of the P layer with respect to the edge of the guide CP.

The respective distance of the electrical contacts of the waveguide PC can in particular be inversely proportional to the width of the waveguide PC.

The represents the intrinsic quality factor Q of the resonant mode (curve 53) and the average density of injected carriers participating in the gain (curve 54) as a function of the distance of the contact P with respect to the edge of the guide CP. It emerges that when said distance increases, the optical losses linked to the absorption of the metallic contact decrease, that is to say that the quality factor Q increases, but the injection efficiency also decreases. It is then necessary to find a compromise, for example by modeling a laser based on these constraints.

The optoelectronic component according to the embodiments described above is a hybrid structure that can be manufactured according to known techniques as follows.

The III-V semiconductor hetero-structure is transferred to a circuitry of waveguides based on silicon (Si) material. The techniques used to produce this transfer may include adhesive bonding, substrate fusion ( “wafer fusion” ), direct substrate transfer by thermocompression, etc. A layer of dielectric material (typically SiO ₂ ) is inserted beforehand between the III-V semiconductor hetero-structure and the circuitry of the Si-based waveguides in order to adjust the strength of the evanescent coupling to the value desired. Typically, the thickness of this adjustment layer varies between 50 nm and 500 nm.

After the transfer, the semiconductor membrane is structured using two levels of lithography followed by plasma-assisted etching, in order to achieve the CP as well as the edge.

The metal contacts located on the P and N layers are defined by lithography. The metals deposited are chosen according to the type of material and doping of the layers used. Annealing of these contacts may be necessary to obtain an ohmic contact. The annealing temperature must not exceed 400°C to remain compatible with CMOS technology.

The structures are then encapsulated in a low index dielectric material.

Finally, electrical connections ( “ vias ” ) are opened and metallized above the metal contacts in order to be able to electrically supply the optoelectronic component.

Of course, the invention is not limited to the examples which have just been described and many adjustments can be made to these examples without departing from the scope of the invention.

Claims

Optoelectronic component (1) adapted to be integrated into an optoelectronic circuit, the component (1) comprising:

a III-V semiconductor membrane comprising:

a P-doped layer (2), called the P layer,

an intrinsic layer (3) deposited on the P layer (2), and

an N-doped layer (4), called the N layer, deposited on the intrinsic layer (3);

an asymmetrical photonic crystal waveguide (6, 16, 26), called the CP waveguide, formed in the membrane by a two-dimensional photonic crystal on one longitudinal side and by a total internal reflection face on the other longitudinal side;

electrical contacts (10, 11) arranged respectively on either side of the CP waveguide (6, 16, 26) in the plane of the membrane, adapted to inject electrical charge carriers into the waveguide CP (6, 16, 26) laterally to the membrane;

the layers (2, 3, 4) being arranged so that the intrinsic and N layers (3, 4) cover the P layer (2) only partially, forming a side face (5) extending perpendicularly from the surface of the P layer (2), a part of the side face (5) forming the face with total internal reflection of the waveguide CP;
the CP waveguide (6, 16, 26) being arranged to be evanescently coupled to a passive semiconductor waveguide (12) in at least one coupling region.
Component (1) according to Claim 1, characterized in that a P contact (10) is arranged on the P layer (2) opposite the lateral face (5) and that an N contact (11) is arranged on the N layer (4) adjacent to the photonic crystal, so that the contacts (10, 11) are arranged parallel to the CP waveguide (6, 16, 26).
Component (1) according to any one of the preceding claims, characterized in that the photonic crystal is formed by holes (7) extending through the N layer (4), the intrinsic layer (3) and the P layer (2), the holes (7) forming a two-dimensional periodic network.
Component (1) according to any one of the preceding claims, characterized in that the PC waveguide (6, 16, 26) comprises a gain region.
Component (1) according to Claim 4, characterized in that the gain region comprises quantum wells and/or quantum dots.
Component (1) according to claim 4 or 5, characterized in that the width of the CP waveguide (6, 16, 26) varies progressively in the at least one coupling region to the passive waveguide (12) .
Component (1) according to Claim 6, characterized in that the respective distance of the electrical contacts (10, 11) with respect to the CP waveguide (6, 16, 26) is inversely proportional to the width of the CP waveguide (6, 16, 26).
Component (1) according to any one of Claims 4 to 7, characterized in that the CP waveguide (6, 16, 26) comprises a region (34) with a slow light regime, in which the photonic crystal comprises a local disturbance.
Component (1) according to the preceding claim, characterized in that the CP waveguide (6, 16, 26) comprises two regions (33) with a fast light regime, arranged respectively upstream and downstream of the region (34 ) at slow light regime.
An optical amplifier, comprising an optoelectronic component (1) according to any one of claims 4 to 9, configured to amplify light propagating in the CP waveguide (6, 6, 26) when charge carriers are injected In this one.
Component (1) according to any one of Claims 1 to 5, in which a resonant optical cavity (20) is formed in the CP waveguide (6, 16, 26) by two mirror regions (27a, 27b) arranged in the direction of propagation of the CP waveguide (6, 16, 26) and by a so-called apodization region (28).
Component (1) according to Claim 11, characterized in that at least one geometric parameter of the photonic crystal in the apodization region (28) varies gradually between the center and the ends of the apodization region (28) in the direction of spread.
Component (1) according to Claim 11 or 12, characterized in that it comprises an additional one- or two-dimensional photonic crystal (17) adjacent to the side face.
Laser source comprising a resonant optoelectronic component (1) according to one of Claims 11 to 13 in combination with Claim 4 or 5.
Optoelectronic circuit, comprising at least one of:

an optoelectronic component (1) according to any one of claims 1 to 9 and 11 to 13,

an amplifier according to claim 10, and

a laser source according to claim 14.