DE102018214807A1 - Photonic system - Google Patents

Abstract

The invention relates to a photonic system comprising an integrated photonic circuit which has at least one thermally sensitive region, at least one light source which is connected to the integrated photonic circuit, and a heat conduction device which is designed to flow heat in at least one direction of the thermally sensitive area starting from the light source in the integrated photonic circuit at least partially, in particular predominantly to be prevented.

Description

Technical field

The invention relates to a photonic system.

The invention further relates to a method for producing a photonic system.

State of the art

It has become known to couple light into a chip via optical waveguides, it being possible here to use either a so-called edge coupling, i.e. coupling light on the chip edge, or a so-called grating coupling, i.e. coupling onto grating couplers from above onto the chip surface. With edge coupling, high positioning accuracy must be maintained in order to transfer the maximum light output into a photonic integrated circuit, or PIC for short, for photonic integrated circuit. In the case of grating coupling, in addition to the lateral positioning of the optical waveguides, they have to be aligned with the chip at a certain angle to the chip surface, for example 8 ° from the normal, an active alignment method being used here. Edge emitters or vertical emitters, VCSEL, can be used in a known manner as light sources for the light.

In a miniaturized photonic system, the light source can be arranged directly on or in the photonically integrated circuit.

The light source, for example one or more lasers, is integrated directly into the PIC for minimal optical losses. If the wavelength of light is to be modulated, for example, for LIDAR applications for the use of FMCW, that is to say frequency-modulated continuous wave, the one or more light sources in particular are integrated into the photonic integrated circuit.

With heterogeneous or monolithic integration of the light source on or in the PIC, heat is generated due to the thermal losses of the light sources. The function of photonic structures in the photonic integrated circuit is strongly temperature-dependent and therefore sensitive to temperature fluctuations and temperature gradients. On the one hand, the emission wavelength of a laser can be shifted by temperature fluctuations, on the other hand, the refractive index of the photonic materials changes with changes in temperature. In order to be able to dissipate the heat, it has become known to apply the photonically integrated circuit to a ceramic substrate, since ceramics have good thermal conductivity properties, among other things. It has also become known to actively cool and / or heat substrates in order to keep the photonic systems at a temperature level that is as defined as possible.

Disclosure of the invention

In one embodiment, the invention provides a photonic system comprising an integrated photonic circuit which has at least one temperature-sensitive region, at least one light source which is connected to the integrated photonic circuit, and a heat conduction device which is embodied in at least one direction To prevent heat flow in the direction of the thermally sensitive region from the light source in the integrated photonic circuit at least partially, in particular predominantly.

• - Bereitstellen eines integrierten photonischen Schaltkreises, der zumindest einen thermisch sensitiven Bereich aufweist, auf einem Substrat,
• - Bereitstellen zumindest einer Lichtquelle, welche mit dem integrierten photonischen Schaltkreis verbunden wird,
• - Bereitstellen einer Wärmeleitungseinrichtung, die ausgebildet wird, in zumindest einer Richtung einen Wärmefluss in Richtung des thermisch sensitiven Bereichs ausgehend von der Lichtquelle im integrierten photonischen Schaltkreis zumindest teilweise, insbesondere überwiegend, zu verhindern.

In a further embodiment, the invention provides a method for producing a photonic system, comprising the steps

• Providing an integrated photonic circuit, which has at least one thermally sensitive region, on a substrate,
• Providing at least one light source which is connected to the integrated photonic circuit,
• - Providing a heat conduction device that is designed to at least partially, in particular predominantly, prevent heat flow in at least one direction in the direction of the thermally sensitive region, starting from the light source in the integrated photonic circuit.

The term “thermally sensitive area” is to be understood in particular to mean an area, a region, an area or the like which has a preferably negative or undesirable influence, effect or the like on one or more components of the photonic system when the temperature changes, in particular increases.

One of the advantages thus achieved is that a compact and inexpensive photonic system with improved heat dissipation and an improved, that is to say more robust, temperature dependence is provided. In other words, temperature-sensitive areas of the photonic integrated circuit are at least partially decoupled from the heat loss of the light source. Another advantage is series production and assembly.

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

According to an advantageous development, the heat conduction device includes a limitation in the integrated photonic circuit. A heat flow to the thermally sensitive region of the photonic integrated circuit is thus avoided in a simple and at the same time reliable manner.

According to a further advantageous development, the heat conduction device extends from the side of the integrated photonic circuit facing away from the light source into the latter. In this way, the light source can be produced, for example, on the upper side, and the heat conduction device can be produced from the rear, so that overall the production is simplified.

According to a further advantageous development, the heat conduction device is designed in the form of a trench. This provides a particularly simple heat conduction device.

According to a further advantageous development, the heat conduction device at least partially surrounds at least one light source. This enables the heat flow to be directed away from the thermally sensitive region of the photonic integrated circuit in a particularly reliable manner.

According to a further advantageous development, the heat conduction device has a plurality of regions which are separate from one another. This reliably directs the heat flow in a desired direction without significantly reducing the overall mechanical stability of the photonic system.

According to a further advantageous development, the heat conduction device is designed in the form of a segment of a circle and / or U-shaped. One of the advantages achieved is that it is easy to manufacture. In addition, it is an advantage that a reliable direction for the heat flow can be predetermined and this can be reliably removed or derived from the thermally sensitive area.

According to a further advantageous development, the heat conduction device has a plurality of regions which are arranged at different distances from the at least one light source. The heat flow is thus conducted away from the thermally sensitive area in an even more reliable manner or is kept away from it.

According to a further advantageous development, the plurality of regions which are arranged at different distances have the same shape, but these are arranged rotated relative to one another. This increases the reliability in preventing heat flow in the direction of the thermally sensitive area. At the same time, the mechanical stability of the photonic system is not significantly reduced.

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 combination indicated in each case, but also in other combinations or on their own without departing from the scope of the present invention.

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

Figure list

• 1 ein photonisches System gemäß einer Ausführungsform der vorliegenden Erfindung;
• 2 Teile von photonischen Systemen gemäß Ausführungsformen der vorliegenden Erfindung;
• 3 Teile eines photonischen Systems gemäß einer Ausführungsform der vorliegenden Erfindung; und
• 4 Schritte eines Verfahrens gemäß einer Ausführungsform der vorliegenden Erfindung.

It shows in schematic form

• 1 a photonic system according to an embodiment of the present invention;
• 2 Parts of photonic systems according to embodiments of the present invention;
• 3 Parts of a photonic system according to an embodiment of the present invention; and
• 4 Steps of a method according to an embodiment of the present invention.

Embodiments of the invention

1 shows a photonic system according to an embodiment of the present invention.

In 1 is a photonic system in detail 1 shown comprising a ceramic substrate 6 on the by means of an adhesive connection 5 a photonic integrated circuit 2 is arranged. On top of the photonic integrated circuit 2 is a laser integrated in this 3 arranged as a light source, which in turn on the top of the photonic integrated circuit with a waveguide 4 connected is. The photonic integrated circuit also has 2 a thermally non-sensitive area 20th and a thermally sensitive area 21 on. These are in 1 on the left side (thermally non-sensitive area 20th ) or on the right side (thermally sensitive area 21 ) arranged. Starting from the light source in the form of the integrated laser 3 becomes now generates heat during its operation, which on the photonic integrated circuit 2 works. For directing the heat flow 8th . 8th' from the light source 3 gone, is a so-called backside trench or trench from the back 7 for thermal decoupling of thermally non-sensitive areas 20th and thermally sensitive area 21 arranged. A front-side trench is also possible, for example to reduce thermal crosstalk between lasers. Especially the backside trench or trench 7 leads to the main heat flow 8th essentially from the thermally sensitive area 21 is kept away or essentially on the thermally non-sensitive area 20th remains limited and in this direction of the ceramic substrate 6 is conducted so that the heat on the ceramic substrate 6 can be dissipated. In other words, one or more rear trenches / trenches 7 in the photonically integrated circuit 2 , a major heat flow 8th through the photonically integrated circuit 2 achieved and the temperature gradient in the photonic structures of the photonically integrated circuit 2 set. Only a small part in the form of a secondary heat flow 8th' can be in the thermally sensitive area 21 penetration. The trench or trenches 7 are arranged in such a way that the dissipation of heat loss, for example, mainly through the area of the photonically integrated circuit below the laser 3 , which acts as a heat source, into the ceramic substrate 6 , which acts as a heat sink, takes place inside. This means that less heat flows into the temperature-sensitive areas 21 the photonic structures, for example ring resonators, phase shifters or the like. The structuring mentioned by trenches on the back 7 to control the heat flow 8th . 8th' is for both heterogeneous and monolithically integrated lasers 3 suitable.

2 shows various parts of photonic systems according to embodiments of the present invention.

In detail are in 2 different heat conduction devices from left to right 7 in the form of trench structures to conduct the heat flow 8th . 8th' looking from the bottom of the photonic integrated circuit 2 towards the light source 3 shown. The light source 3 in the form of a rectangular laser is arranged here in the center and only hinted at.

On the left side of the 2 are semicircular trenches 7a . 7b to the laser 3 arranged. The trenches are above and below 7a . 7b arranged separately from each other.

In the middle of 2 are instead of the semicircular trenches 7a . 7b essentially U-shaped, angular trenches 7a . 7b arranged so that essentially a square area is limited by the trenches 7a . 7b results in the middle of the laser 3 is arranged.

On the right side of the 2 is essentially the same arrangement as on the left side of the 2 shown. In contrast, are radially outside of the two semicircular trenches 7a . 7b now more semicircular trenches 7a ' . 7b ' essentially concentric with the inner trenches 7a . 7b arranged, these opposite the radially inner trenches 7a . 7b in the view shown 2 are rotated by 90 °. In the 2 Openings shown on the left side above and below between the two trenches 7a . 7b are in the radially outer trenches 7a ' . 7b ' now arranged on the left or right side. The radially inner trenches 7a . 7b have a distance here, for example 15a from the center of the laser 3 that is smaller than the distance 15b the radially outer trenches 7a ' . 7b ' , these can also be interpreted differently.

3 shows parts of a photonic system according to an embodiment of the present invention.

In 3 a photonic integrated circuit 2 shown which several, here four lasers 3 has as light sources. These are over a common ditch 7 thermal from the photonically sensitive area 21 of the photonic integrated circuit 2 decoupled.

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

In 4 a method of manufacturing a photonic system is shown.

This is done in a first step S1 providing an integrated integrated photonic circuit, which has at least one thermally sensitive region, on a substrate.

This is followed in a second step S2 providing at least one light source which is connected to the integrated photonic circuit.

This is followed in a third step S3 provision of a heat conduction device which is arranged in the integrated photonic circuit and which is designed to at least partially, in particular predominantly, prevent heat flow in at least one direction in the direction of the thermally sensitive region starting from the light source in the integrated photonic circuit.

• - Kostengünstige Herstellung.
• - Kompaktes photonisches System.
• - Gute Entwärmung des photonischen Systems.
• - Serientaugliche Herstellung.
• - Zuverlässiges Betreiben des photonischen Systems.

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

• - Inexpensive manufacture.
• - Compact photonic system.
• - Good cooling of the photonic system.
• - Production-ready production.
• - Reliable operation of the photonic system.

Although the present invention has been described on the basis of preferred exemplary embodiments, it is not restricted to these but can be modified in a variety of ways.

Claims (10)

Photonic system (1) comprising an integrated photonic circuit (2) which has at least one thermally sensitive area (21), at least one light source (3) which is connected to the integrated photonic circuit (2), and a heat conduction device (7 , 7a, 7a ', 7b, 7b'), which is designed to have a heat flow (8, 8 ') in at least one direction in the direction of the thermally sensitive region (21), starting from the light source (3) in the integrated photonic circuit (2 ) to prevent at least partially, especially predominantly. System according to Claim 1 , wherein the heat conduction device (7, 7a, 7a ', 7b, 7b') comprises a limitation in the integrated photonic circuit. System according to Claim 1 or 2 , The heat conduction device (7, 7a, 7a ', 7b, 7b') extending from the side (10) of the integrated photonic circuit (2) facing away from the light source (3). System according to Claim 3 , wherein the heat conduction device (7, 7a, 7a ', 7b, 7b') is in the form of a trench. System according to one of the Claims 1 - 4 , wherein the heat conduction device (7) at least partially surrounds the at least one light source (3). System according to Claim 5 , wherein the heat conduction device (7, 7a, 7a ', 7b, 7b') has several separate areas (7a, 7b, 7a ', 7b'). System according to Claim 6 , wherein the heat conduction device (7, 7a, 7b, 7a ', 7b') is circular and / or U-shaped and / or rectangular. System according to one of the Claims 5 - 7 , The heat conduction device (7, 7a, 7b, 7a ', 7b') has a plurality of regions (7a, 7a ', 7b, 7b'), which are arranged at different distances (15a, 15b) from the at least one light source (3) . System according to Claim 8 , the plurality of regions (7a, 7b, 7a ', 7b'), which are arranged at different distances (15a, 15b), have the same shape, but are arranged rotated relative to one another. A method of manufacturing a photonic system (1) comprising the steps - Providing (S1) an integrated photonic circuit (2), which has at least one thermally sensitive area (21), on a substrate (6), Providing (S2) at least one light source (3) which is connected to the integrated photonic circuit (2), - Providing (S3) a heat conduction device (7, 7a, 7b, 7a ', 7b'), which is formed in at least one direction, a heat flow (8, 8 ') in the direction of the thermally sensitive area (21) from the light source (2) in the integrated photonic circuit (2) at least partially, in particular predominantly.

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