DE102019217522A1 - Photonic system and method for operating a photonic system - Google Patents

Abstract

The invention relates to a photonic system comprising a substrate, at least one temperature-sensitive photonic component which is arranged on the substrate, the temperature-sensitive photonic component or a further component being heated during operation and providing a first temperature gradient in the photonic system, a heating device which is arranged and designed such that it provides a second temperature gradient which is at least partially opposite to the first temperature gradient.

Description

Technical area

The invention relates to a photonic system comprising a substrate and at least one photonic component which is arranged on the substrate and which heats up during operation and provides a temperature gradient in the photonic system.

The invention further relates to a method for operating a photonic system comprising a substrate and at least one photonic component which is arranged on the substrate and which heats up during operation and provides a temperature gradient in the photonic system.

Although the present invention is generally applicable to any photonic components, the present invention will be described in terms of silicon-based photonic components.

State of the art

Silicon-based photonic components have a high thermo-optical coefficient TOC, i.e. the refractive index n of silicon for photonic components changes with temperature. A change in the refractive index Δn can therefore lead to changes in the function of the photonic components. For example, a change in the refractive index can lead to undesired phase shifts Δφ and such changes thus represent a problem in phase-sensitive photonic components. Typical examples of phase-sensitive photonic components are ring resonators, directional couplers. directional couplers, optical phase arrays, engl. optical phased arrays, OPA and arrayed waveguide gratings AWG.

Since the function of such photonic components is temperature-dependent, thermal management for photonic ICs (PICs), i.e. photonic integrated circuits and photonic systems, is required which, in addition to heat dissipation, also includes temperature stabilization.

The efficiency of heat dissipation depends on the selection of suitable materials. The heat dissipation takes place in a known manner by using substrates with high thermal conductivity, for example ceramics, and by using thermally conductive adhesives, for example silver-filled adhesives. As an alternative to ceramic substrates, so-called “thermal vias”, ie thermal through-hole plating, are often used in order to specifically influence the thermal conductivity in certain positions.

Temperature stabilization, in turn, requires the control of temperature fluctuations, such as seasonal or application-related temperature fluctuations. This takes place in a known manner by means of complex active cooling or heating of the entire photonic system. For example, thermoelectric generators are used for this purpose. thermo-electric coolers, TEC, are used to compensate for fluctuations in the overall temperature of the photonic system.

If the structure of a photonic system is to be made compact, then heat-generating components such as laser chips and / or electrical ICs must be integrated directly on the photonic IC. With the direct integration of heat sources on or in the PIC, a large amount of heat is generated in the photonic IC, which leads to temperature gradients.

From the WO 2017/213768 A1 a photonic system with heating elements has become known, which are embedded, for example, in the oxide layer below light guides, and can be set up to impress a temperature gradient and thus manipulate a phase offset.

Disclosure of the invention

In one embodiment, the present invention provides a photonic system comprising
a substrate,
at least one temperature-sensitive photonic component which is arranged on the substrate, wherein the temperature-sensitive photonic component or a further component heats up during operation and provides a first temperature gradient in the photonic system,
a heating device which is arranged and designed in such a way that it provides a second temperature gradient which is at least partially opposite to the first temperature gradient.

• - Detektieren zumindest eines Temperaturgradienten,
• - Berechnen zumindest eines dem detektierten zumindest einen Temperaturgradienten inversen Temperaturgradienten,
• - Berechnen zumindest eines Betriebsparameters der Heizeinrichtung, insbesondere der Heizleistung der Heizeinrichtung, zur Bereitstellung des zumindest einen inversen Temperaturgradienten, der zumindest teilweise dem detektierten Temperaturgradienten entgegengesetzt ist,
• - Steuern der Heizeinrichtung anhand des zumindest einen berechneten Betriebsparameters.

In a further embodiment, the present invention provides a method of operating a photonic system comprising
a substrate,
at least one temperature-sensitive photonic component which is arranged on the substrate, the temperature-sensitive photonic component or a further component being heated during operation and providing a first temperature gradient in the photonic system, and
a heater comprising the steps

• - Detecting at least one temperature gradient,
• - Calculating at least one temperature gradient which is the inverse of the detected at least one temperature gradient,
• - Calculating at least one operating parameter of the heating device, in particular the heating power of the heating device, to provide the at least one inverse temperature gradient which is at least partially opposite to the detected temperature gradient,
• - Controlling the heating device on the basis of the at least one calculated operating parameter.

One of the advantages achieved in this way is that a miniaturized, compact and inexpensive photonic system is provided which comprises an integrated heating device which, through selective heating, reduces the (overall) temperature gradient across phase-sensitive components.

In other words, the heating device according to embodiments of the invention enables the overall temperature gradient of the photonic system to be minimized by selective heating by means of the heating device.

The term “photonic component” is to be understood in the broadest sense, that is to say as any component of the photonic system, in particular phase-sensitive optical components. Photonic components can include, but are not limited to, ring resonators, directional couplers, optical phase arrays and / or arrayed waveguide gratings.

The term “temperature-sensitive” in relation to “photonic component” means, in particular, that properties of the photonic component that are essential for the operation of the photonic system change significantly with the temperature, in particular the proper operation of the photonic system does not or does not not only marginally influence.

Further features, advantages and further embodiments of the invention are described below or become apparent as a result.

According to an advantageous development, the heating device comprises several, in particular independently controllable, heating elements. This further improves the compensation of the first temperature gradient: several heaters or heating elements can be used to selectively heat at different positions, which enables a more finely resolved compensation of the first temperature gradient.

According to a further advantageous development, at least one, in particular all, heating elements are arranged on the substrate. This enables a particularly simple production of the photonic system.

According to a further advantageous development, at least one of the heating elements is arranged in the vertical direction above the at least one photonic component, in particular at a distance from it. The advantage of this is that an even more finely resolved compensation of the first temperature gradient can be provided.

According to a further advantageous development, at least one of the heating elements is essentially at least partially linear, rectangular, segment of a circle, triangular and / or arcuate. This enables an even more finely resolved compensation of the first temperature gradient with a space-saving arrangement at the same time. Due to the different shape, corresponding heating elements can be flexibly adapted to different available installation space, if necessary also between different photonic components, which enables effective use of the tree space.

According to a further advantageous development, the heating device, in particular the heating elements, is arranged essentially symmetrically around the at least one photonic component in at least one plane. The arrangement in two different levels is also conceivable. Overall, a space-efficient arrangement of the heating device “around” the photonic component “around” and, at the same time, an effective compensation of the first temperature gradient is provided.

According to a further advantageous development, at least one of the heating elements is designed as a metallic heating element, as a silicon-doped heating element and / or as a heating element with a plurality of graphene layers. In this way, heating elements are made available in a flexible manner tailored to the respective requirements.

According to a further advantageous development, at least one temperature measuring device for detecting at least one temperature gradient and a control device for the heating device are arranged, the control device being designed to use the at least one temperature gradient determined by the temperature measuring device to control the heating device in such a way that the at least one determined temperature gradient is minimized becomes. This enables extremely efficient compensation of the first temperature gradient. The temperature measuring device can for this purpose have temperature sensors in different numbers and / or designs, which can also be arranged in different planes and / or positions in the photonic system.

According to a further advantageous development of the method, the steps are carried out repeatedly. This enables extremely efficient and ongoing compensation of the first temperature gradient. Different utilization, i.e. heating of components of the photonic system during operation, can thus be taken into account.

According to a further advantageous development of the method, the steps are carried out regularly, in particular periodically, and / or in an event-induced manner. In this way, for example, energy can be saved or the first temperature gradient can only be compensated when required and, if necessary, only to a certain extent.

According to a further advantageous development, the steps are carried out again until a difference between a current and an earlier temperature gradient falls below a predeterminable value. This enables an extremely efficient and, at the same time, energy-saving compensation of the first temperature gradient.

Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures on the basis of the drawings.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or on their own, without departing from the scope of the present invention.

Preferred designs and embodiments of the invention are shown in the drawings and are explained in more detail in the following description, with the same reference symbols referring to the same or similar or functionally identical components or elements.

Figure list

• 1 unterschiedliche Heizeinrichtungen eines photonischen Systems gemäß Ausführungsformen der vorliegenden Erfindung;
• 2 unterschiedliche Heizeinrichtungen eines photonischen Systems gemäß Ausführungsformen der vorliegenden Erfindung;
• 3 unterschiedliche Heizeinrichtungen eines photonischen Systems gemäß Ausführungsformen der vorliegenden Erfindung;
• 4 Schritte eines Verfahrens gemäß einer Ausführungsform der vorliegenden Erfindung;
• 5 einen Temperaturgradienten eines photonischen Systems gemäß einer Ausführungsform der vorliegenden Erfindung;
• 6 den Temperaturgradienten der 5 entlang zweiter Achsen des photonischen Systems bei ausgeschalteter Heizeinrichtung; und
• 7 den resultierenden Temperaturgradienten der 5 entlang der beiden Achsen des photonischen Systems bei eingeschalteter Heizeinrichtung.

It shows

• 1 different heating devices of a photonic system according to embodiments of the present invention;
• 2 different heating devices of a photonic system according to embodiments of the present invention;
• 3 different heating devices of a photonic system according to embodiments of the present invention;
• 4th Steps of a method according to an embodiment of the present invention;
• 5 a temperature gradient of a photonic system according to an embodiment of the present invention;
• 6th the temperature gradient of the 5 along second axes of the photonic system with the heating device switched off; and
• 7th the resulting temperature gradient of the 5 along the two axes of the photonic system with the heating device switched on.

Embodiments of the invention

1 shows different heating devices of a photonic system according to embodiments of the present invention.

In 1 are each a photonic system from left to right in plan view 1 with a photonic component 3 by one or more heating elements 4a , 4b , 4c , 4d is surrounded, shown. In the 1 on the left is a single linear heating element 4a parallel to one side of the essentially rectangular or square photonic component 3 arranged. The photonic component 3 is square here, but can also have a different geometry, for example circular. In the figure to the right there are two linear heating elements 4a , 4b - above and below - parallel to the respective sides of the photonic component 3 , so on opposite sides, arranged. In the third figure from the left there are four heating elements 4a , 4b , 4c , 4c arranged, each along one of the sides of the photonic component 3 extend. In the figure on the far right are linear heating elements of different lengths 4th and L-shaped heating elements or heating elements which are bent at right angles are arranged, which the photonic component 3 and together essentially form a square.

It is therefore possible to have a large number N of heating elements on any side around a photonic component 3 around and / or on one or more edges, sections and the like of the photonic component 3 align. The larger N, the more varied the temperature setting options and the lower the remaining temperature gradient with appropriate wiring.

2 shows different heating devices of a photonic system according to embodiments of the present invention.

In 2 there are four photonic systems in the upper and lower half from left to right in plan view 1 each with a photonic component 3 shown by one or more heating elements 4a , 4b , 4c , 4d , is surrounded. In the 2 At the top left are the four heating elements 4a , 4b , 4c , 4d each section arranged linearly analogous to a shape of a hat in the plan view, with the respective middle area further from the photonic component 3 than the respective edge areas is removed. Deviations or combinations from or with the in 2 shown and also with those in the 1 and 3 heating elements shown possible, for example, could be in the 2 At the top left only one heating element has a hat shape and all the others are linear or arcuate. Or in 2 In the upper right corner, all heating elements could have the same geometry.

In the 2 top right are essentially above and below the photonic component 3 rectangular heating elements of different widths and flat areas 4a , 4b shown. There are heating elements on the left and right sides 4c , 4d arranged in the form of right triangles, which are tapered from bottom to top, with one side parallel to the adjacent side of the photonic component 3 is arranged.

In the 2 at the bottom left are four arched heating elements 4a , 4b , 4c , 4d arranged substantially along the four sides of the photonic components 3 extend arcuately. In the 2 at the bottom right are also arched heating elements 4th arranged. However, its radius is designed so that it is essentially circular around the photonic component 3 are arranged around, thus forming a circle as a whole.

In other words, in 2 different possible geometries and arrangements of heating elements of photonic systems 1 shown to compensate for the photonic component 3 to improve generated temperature gradients.

In addition to the "linear" heating elements of the 1 so are in 2 further heating element geometries shown. For example, the geometry of the individual heating elements can be optimized so that the temperature profiles generated by the heating elements correspond to the desired application. Depending on the technological design, this optimization is either carried out by adapting the width of the heating element (s. 2 top right), adaptation of the course of the heating element line (s. 2 top left) and / or by adapting the heating element conductivity as a function of the location (in 2 not shown). If the heating elements are designed as doped semiconductors, the doping strength can be varied in the course of the heating element in order to change the thermal conductivity.

As already mentioned, the geometry of the heating elements is, for example, curved (see Sect. 2 bottom left) or circular (s. 2 below right) heating elements into consideration. As a result, a homogeneous temperature profile and thus smaller temperature gradients can be achieved.

3 shows different heating devices of a photonic system according to embodiments of the present invention.

In 3 is a side view at the top and a plan view of a photonic system at the bottom 1 shown. Here is in each case on a substrate 2 a photonic component in the form of a buried oxide layer 3 arranged. On both sides of the photonic component 3 of the photonic system 1 (see 3 left) is a rectangular heating element 4a , 4b arranged, which is also on the surface of the substrate 2 is arranged. The heating elements 4a , 4b and the photonic component 3 are with an overlap 5 covered, which is made of low refractive index material. In contrast to this, the photonic system has 1 on the right side of the 3 instead of the side heating elements 4a , 4b a heating element 4a on top of the overlap 5 on. There are also four temperature measuring sensors 6th shown, which are arranged here partly on the substrate, partly on the cover and with a control device 7th for the heating element 4a are connected to its control. It is also conceivable to use the temperature measuring sensors 6th only on the overlap 5 or just on the substrate 2 to arrange.

Depending on the technological design, the heating elements are integrated in different positions of the photonic IC. Examples of possible technological designs are metallic heating elements, heating elements made of doped silicon and graphene layers as heating elements.

1. 1. Heizelemente in der gleichen Schicht wie die photonische Komponente 3 („Seitenheizer“)
2. 2. Heizelemente auf einer Schicht oberhalb der photonischen Komponente 3 („Obenliegende Heizer“)

The selection of the technological version can on the one hand depend on the availability of the different technologies in the manufacturing process of the photonic IC depend, on the other hand, this is determined by the desired position of the heating elements relative to the photonic component. The following positions, among others, are conceivable:

1. 1. Heating elements in the same layer as the photonic component 3 ("Side heater")
2. 2. Heating elements on a layer above the photonic component 3 ("Overhead heater")

Since some applications do not have an overlap 5 which allow photonic structures, for example to couple light out and in, the use of overhead heating elements is not possible in this case and lateral heating elements are used. Depending on the application of the photonic IC, the use of side heating elements, overhead heating elements and / or a combination of both is advantageous.

In addition to integrating heating elements, temperature sensors can also be integrated into the photonic IC. Similar to the heating elements, different geometric designs of the temperature sensors are conceivable. Furthermore, a different number of temperature sensors can be integrated at different points relative to the photonic components. These temperature sensors can then be used to record the temperature gradients.

4th shows steps of a method according to an embodiment of the present invention.

• In einem ersten Schritt S1 werden der oder die Temperaturgradienten detektiert.
• Dies kann beispielsweise anhand mehrerer Temperatursensoren 6 erfolgen oder durch, beispielsweise interferometrische, Bestimmung der Phasenfehler, die in den photonischen Komponenten 3 hervorgerufen werden.

The method for operating a photonic system to reduce temperature gradients here comprises four steps S1-S4 :

• In a first step S1 the temperature gradient (s) are detected.
• This can be done, for example, using several temperature sensors 6th take place or by, for example interferometric, determination of the phase errors that occur in the photonic components 3 be evoked.

After temperature gradients are known, a further step is carried out S2 an inverse temperature gradient is calculated. This is the temperature gradient required to at least partially compensate for the original temperature gradient.

Then in a further step S3 the heating element power required to generate the inverse temperature gradient is calculated. This is done, for example, using a thermal model of the IC.

This heating power is applied to the individual heating elements 4th implemented accordingly or operated accordingly (step S3 ' ) and the remaining temperature gradient is determined again. Should the set temperature gradient not meet the required specifications of the photonic system 1 match, the heating element output continues iteratively (step S6 ) customized. This process can be repeated until the desired temperature stability is achieved (step S5 ).

5 shows a temperature gradient of a photonic system according to an embodiment of the present invention, 6th shows the temperature gradient of the 5 along two axes of the photonic system with the heating device switched off and 7th the resulting temperature gradient for the photonic system of 5 along the two axes of the photonic system with the heating device switched on.

In 5 a two-dimensional temperature gradient across a photonic IC is shown. This temperature gradient causes various temperature differences in the photonic component shown 3 . The heating elements 4a , 4b , 4c , 4d are in accordance with the 2 formed and arranged at the top left.

The temperature gradients in the photonic component 3 are now using all four available heating elements 4a , 4b , 4c , 4d balanced. The procedure follows the procedure described above for operating the heating elements. In particular, this process is carried out iteratively until a temperature difference of less than 0.1 K is reached.

An original temperature difference of 15 K across the photonic system 1 is thus reduced to around 0.1 K. The diagrams show the course of the temperature along the horizontal (reference numbers 16 ) and vertical (reference numerals 15th ) Lines for switched off and switched on heating elements 4a , 4b , 4c , 4d .

• • Kompaktes, kostengünstiges photonisches System
• • Robust gegenüber Temperaturveränderungen
• • Einfache Implementierung
• • Serientauglichkeit

In summary, at least one of the embodiments of the invention has at least one of the following advantages:

• • Compact, inexpensive photonic system
• • Robust against temperature changes
• • Easy to implement
• • Suitability for series production

At least one embodiment of the present invention encompasses or enables one Realization and use of one or more integrated heating elements on photonic chips in order to minimize temperature gradients in these chips through selective heating. The geometry and number of heating elements as well as the applied heating power are in particular defined in such a way that the temperature gradients generated by the integrated heating elements counteract the temperature gradients originally present in the photonic system. In this way, the effective temperature gradients in the PIC are minimized or completely prevented. Preferably only the temperature-sensitive area of the PIC is taken into account. The temperature gradient can be recorded either statically or a priori, for example by means of a temperature model of the photonic system, or dynamically during operation. In the latter case, the temperature can either be measured point by point using integrated temperature sensors and conclusions can be drawn about the temperature gradient or the temperatures in the rest of the chip using a model, or the influence of the temperature can be deduced from the behavior of the photonic system, or by evaluating a phase error a phase sensitive photonic component.

The use of heating elements is suitable both for individual phase-sensitive components and for a large array of phase-sensitive components.

Although the present invention has been described on the basis of preferred exemplary embodiments, it is not restricted thereto, but rather can be modified in many ways.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2017/213768 A1 [0009]

Claims (12)

Photonic system (1), comprising a substrate (2), at least one temperature-sensitive photonic component (3) which is arranged on the substrate (2), wherein the temperature-sensitive photonic component or a further component heats up during operation and provides a first temperature gradient in the photonic system (1), a heating device (4a, 4b, 4c, 4d, ...) which is arranged and designed in such a way that it provides a second temperature gradient which is at least partially opposite to the first temperature gradient. Photonic system (1) according to Claim 1 , wherein the heating device (4a, 4b, 4c, 4d, ...) comprises several, in particular independently controllable, heating elements (4a, 4b, 4c, 4d, ...). Photonic system according to one of the Claims 1 - 2 , wherein at least one, in particular all heating elements (4a, 4b, 4c, 4d, ...) are arranged on the substrate (2). Photonic system according to one of the Claims 1 - 3 , wherein at least one of the heating elements (4a, 4b, 4c, 4d, ...) is arranged in the vertical direction above the at least one photonic component (3), in particular at a distance from it. Photonic system according to one of the Claims 1 - 4th , wherein at least one of the heating elements (4a, 4b, 4c, 4d, ...) is essentially linear, rectangular, segment of a circle, triangular and / or arcuate. Photonic system according to one of the Claims 1 - 5 , the heating device (4), in particular the heating elements (4a, 4b, 4c, 4d, ...) being arranged essentially symmetrically around the at least one photonic component (3) in at least one plane. Photonic system according to one of the Claims 1 - 6th , wherein at least one of the heating elements (4a, 4b, 4c, 4d, ...) is designed as a metallic heating element, as a silicon-doped heating element and / or as a heating element with several graphene layers. Photonic system according to one of the Claims 1 - 7th , at least one temperature measuring device (6) for detecting at least one temperature gradient and a control device (7) for the heating device (4) being arranged, the control device (7) being designed to use the at least one temperature gradient determined by the temperature measuring device (6) To control the heating device (4) in such a way that the at least one determined temperature gradient is minimized. A method for operating a photonic system (1), comprising a substrate (2), at least one temperature-sensitive photonic component (3) which is arranged on the substrate (2), the temperature-sensitive component or a further component being heated during operation and a first temperature gradient in the photonic system (1) provides, and a heating device (4), comprising the steps - Detecting (S1) at least one temperature gradient, - Calculating (S2) at least one temperature gradient that is inverse to the detected at least one temperature gradient, - Calculating (S3) at least one operating parameter of the heating device (4), in particular the heating power of the heating device (4), to provide the at least one inverse temperature gradient which is at least partially opposite to the detected temperature gradient, - Controlling (S3 ') the heating device (4) on the basis of the at least one calculated operating parameter. Procedure according to Claim 9 wherein steps (S1, S2, S3, S3 ') are repeatedly performed. Procedure according to Claim 10 , wherein the steps (S1, S2, S3, S3 ') are carried out regularly, in particular periodically, and / or event-induced. Method according to one of the Claims 10 - 11 , the steps (S1, S2, S3, S3 ') being carried out again until a difference between a current and an earlier temperature gradient falls below a predeterminable value.

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