阅读说明：本技术 光子集成电路 (Photonic integrated circuit ) 是由 S·普罗伊 于 2020-02-26 设计创作，主要内容包括：公开了一种光子集成电路,包括：介质基片(110)；介质基片(110)上用于引导太赫兹(THz)波的介质波导装置(120)；以及在介质波导装置(120)的表面区域中具有金属化部分的局部功能化部分(130)。金属化部分沿着THz波的传播方向局部化,以允许THz波在局部功能化部分之外进行无金属化传播。(Disclosed is a photonic integrated circuit including: a dielectric substrate (110); a dielectric waveguide device (120) on the dielectric substrate (110) for guiding terahertz (THz) waves; and a locally functionalized portion (130) having a metallization in a surface region of the dielectric waveguide arrangement (120). The metalized portion is localized along a propagation direction of the THz wave to allow unmetallized propagation of the THz wave outside the localized functionalized portion.)

1. A photonic integrated circuit having:

a dielectric substrate (110);

a dielectric waveguide device (120) on the dielectric substrate (110) for guiding terahertz (THz) waves; and

a locally functionalized portion (130) comprising a metallization in a surface region of the dielectric waveguide device (120), wherein the metallization is localized along a propagation direction of the THz wave such that the THz wave can propagate without metallization outside the locally functionalized portion.

2. The photonic integrated circuit according to claim 1, wherein the dielectric waveguide device (120) comprises an extension (d) perpendicular to the THz wave propagation direction, the extension being in the range of 10 μ ι η to 300 μ ι η or 30 μ ι η to 100 μ ι η, and the refractive index of the material of the dielectric waveguide device (120) is at least 1.5 times the refractive index of the dielectric substrate (110).

3. A photonic integrated circuit according to claim 1 or 2, wherein the dielectric waveguide device (120) comprises a bifurcation having a branch point (123) and a surface region of the locally functionalized portion (130) is formed by an opposing surface adjacent to the branch point (123).

4. The photonic integrated circuit according to any of the preceding claims, further comprising a diode (140) for generating THz oscillations,

wherein the dielectric waveguide device (120) forms a Vivaldi antenna coupled to the diode (140) and has, starting from the diode (140), a widened opening portion (125) for radiating THz waves, and

wherein the metallization (130) is formed on both sides of the widened opening portion (125) to support coupling of the THz oscillation from the diode (140) to the Vivaldi antenna.

5. The photonic integrated circuit of any one of the preceding claims, further comprising:

at least one THz resonator (150) and a bottom layer (160), wherein the THz resonator (150) comprises a dielectric material having a higher refractive index than the dielectric substrate (110) and is arranged laterally offset from the dielectric waveguide arrangement (120) along the dielectric substrate (110), the bottom layer (160) being arranged on the opposite side of the dielectric substrate (110) to the THz resonator (150),

wherein the metalized portion (130) is locally formed in a region where the distance between the dielectric waveguide device (120) and the THz resonator (150) is smallest, namely on a surface of the dielectric waveguide device (120) opposite to the dielectric substrate (110) and/or the THz resonator (150).

6. The photonic integrated circuit of any one of the preceding claims, further comprising:

a further dielectric substrate, wherein the dielectric waveguide arrangement (120) is arranged between the dielectric substrate (110) and the further dielectric substrate, and wherein the refractive index of the further dielectric substrate is at least 1.5 times smaller than the refractive index of the dielectric waveguide arrangement (120).

7. A method of fabricating a photonic integrated circuit, comprising the steps of:

providing a dielectric substrate (110);

forming a dielectric waveguide device (120) for guiding THz waves on the dielectric substrate (110); and

functionalizing a localized surface region (130) of the dielectric waveguide device (120) by forming a metallization on the localized confined surface region (130).

8. The method of claim 7, wherein forming the dielectric waveguide device (120) and forming the metalized portion (130) comprise one of:

-lithographic structuring;

-an etching process;

-a layer of adhesive medium; and

-evaporating the metal.

9. Method for guiding THz waves using a photonic integrated circuit according to any of claims 1 to 6, wherein the local functionalization by the metallization (130) achieves at least one of the following effects:

suppressing higher order modes of the THz wave;

coupling or decoupling modes of the THz wave;

converting a mode of the THz wave to another mode.

Technical Field

The invention relates to a photonic integrated circuit and a method of manufacturing or using the same.

Background

Waveguide structures, particularly functionalized waveguides, are highly relevant structures that can be used in many frequency ranges (from microwave radiation above terahertz (100GHz-10THz) to visible light). Metal hollow waveguides are used in the microwave range and partly also in the terahertz range. The waveguides consist of a metal block in which waveguides, usually with a rectangular cross section, are milled out and usually filled with air.

The width of the hollow core waveguide should be at least λ/2(λ is the wavelength of the respective wave) in order to be able to guide the mode. This defines the lower frequency limit for a given geometry. Below this frequency, either the mode cannot propagate or the wave decays exponentially. The upper frequency limit is caused by the oscillation of undesired higher order propagation modes. While these modes can propagate, components integrated into the waveguide (e.g., frequency multipliers or beam splitters) are suitable for terrestrial modes and are less efficient in the higher order modes.

Typical functionalities are switches, splitters, microstrip conversion with integrated frequency multipliers or Intermediate Frequency (IF) mixers, horn antennas for radiation, etc.

The disadvantages of hollow core waveguides are increased losses at THz frequencies and production costs, since hollow core waveguides are typically machined by milling or the like. This process is not scalable and as the frequency increases (smaller and smaller in size) it requires better and better manufacturing accuracy, which should be a fraction of the operating wavelength λ. When the frequency is 10GHz, the wavelength is 3cm, and the manufacturing tolerance has room; on the other hand, at a frequency of 1THz, the wavelength is only 300. mu.m, and thus high manufacturing accuracy is required.

Another disadvantage of hollow core waveguides is loss, which increases dramatically with increasing operating frequency. In addition to pure line loss, the increase in surface roughness and skin effect play an important role. At lower frequencies, the losses can be orders of magnitude higher than those of pure metal lines with ideal structures.

Planar waveguides such as microstrip lines and coplanar waveguides also have high losses at higher THz frequencies.

Accordingly, there is a need for a functionalized waveguide structure that can be used in the THz range (100GHz-10THz) and overcome at least some of the above-mentioned problems.

Disclosure of Invention

At least part of the above problems are solved by a photonic integrated circuit according to claim 1 and a method of manufacturing or using the photonic integrated circuit according to claim 6 or 8. The dependent claims relate to advantageous further embodiments of the object of the independent claims.

The invention relates to a photonic integrated circuit having a dielectric substrate, a dielectric waveguide device for guiding terahertz (THz) waves on the substrate, and a locally functionalized portion having a metallization in a surface region of the dielectric waveguide device. The metalized portion is localized along a propagation direction of the THz wave to allow unmetallized propagation of the THz wave outside the localized functionalized portion. The term "non-metallized" refers to other structures (e.g., metals or other materials with a sufficient number of free charge carriers) that force the electric field strength to zero far enough so that they do not affect the THz wave.

The term "photonic" shall mean that the signal propagation is based on photons, in particular using frequencies in the THz range (100GHz-10 THz). Which is also the boundary line of the power line. In order for the dielectric waveguide device to guide these THz waves efficiently, the dielectric waveguide device has an extension, in particular perpendicular to the THz wave propagation direction, in a range such as from 10 μm to 300 μm or from 30 μm to 100 μm (or about 50 μm). Furthermore, a material having a refractive index at least 1.5 times the refractive index of the (adjacent) dielectric substrate may be selected for the waveguide arrangement. Materials such as PE (polyethylene) or quartz (n 2.15) having a refractive index n (PE) of 1.4 to 1.6 may be used for the dielectric substrate, and silicon such as silicon having a refractive index n (si) of 3.416 may be used as the material of the waveguide device.

According to embodiments, there is no continuous metal layer on or near the waveguide that is disposed along a standard waveguide that would otherwise negatively impact wave propagation. According to an embodiment, the metallization is formed only where some functionalization is desired. In particular, the metallization can only be formed on one side of the waveguide structure to shift the THz wave. Further functionalization relates in particular to the curved surface region of the waveguide, since modes are usually suppressed or mode conversion of THz waves is to be performed there. Such bending may be accompanied by a change (e.g. a decrease) in the cross-section perpendicular to the propagation direction.

According to an embodiment, local functionalization may refer to one or more of the following elements: waveguides with modified mode structure, switches, beam splitters, polarizers, transitions to hollow waveguides, microstrip lines or coplanar waveguides with integrated frequency multipliers or Intermediate Frequency (IF) mixers, horn antennas for radiation, etc. In the implementation of these elements, local functionalization may result in, for example: higher order mode suppression of THz waves, coupling or decoupling of THz wave modes, conversion of THz wave modes to another mode, etc.

For example, the waveguide arrangement may optionally have a bifurcation (e.g. a beam splitter) with a branch point, and the surface region of the locally functionalized portion may be formed by the opposing surface adjacent to the branch point.

The photonic integrated circuit may also have a device (e.g. a diode or another active element) for generating and/or receiving THz oscillations, and the waveguide arrangement may have, for example, a vivaldi antenna coupled to the device and, starting from the diode, a widened opening portion for radiating the coupled THz waves. In this embodiment, metallisation may be formed on both sides of the widened opening portion to support coupling of THz oscillations from the device to the vivaldi antenna and ultimately into the dielectric waveguide. The device (e.g. a diode or another active element) may act as a source and/or detector of THz oscillations.

The photonic integrated circuit may also have at least one THz resonator having a dielectric material and disposed laterally offset from the waveguide arrangement along the substrate. In particular, a gap may be formed therebetween. Optionally, the side of the substrate opposite the THz resonator is also provided with a bottom or shielding layer (e.g. made of metal). The material of the resonator also has a higher refractive index than the substrate and is optionally formed of the same material as the waveguide arrangement. In this embodiment, the metallization may be formed locally in the region where the distance between the waveguide arrangement and the THz resonator is minimal, i.e. on the surface of the waveguide arrangement opposite the substrate or the THz resonator. Thus, coupling of THz waves into the resonator is facilitated.

Optionally, a further dielectric substrate is formed in the circuit, wherein the dielectric waveguide arrangement is arranged between the dielectric substrate and the further dielectric substrate. The refractive index of the further dielectric substrate may be at least 1.5 times lower than the refractive index of the dielectric waveguide arrangement.

Drawings

Embodiments of the invention will be better understood from the following detailed description and drawings of various embodiments, which are, however, for purposes of explanation and understanding only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 illustrates an embodiment of a photonic integrated circuit.

Fig. 2 illustrates another embodiment of a photonic integrated circuit coupled with an exemplary diode.

Fig. 3 illustrates another embodiment of a photonic integrated circuit coupled with an exemplary THz resonator.

Embodiments are also related to a method of fabricating a photonic integrated circuit. The method comprises the following steps:

-providing a dielectric substrate;

-forming dielectric waveguide means on the substrate for guiding THz waves; and

-functionalizing the locally confined surface region of the dielectric waveguide device by forming a metallization on the local surface region.

The production can take place in particular by coating the conductive layer using a photolithographic and/or etching process for structuring or a laser cutting process and/or an adhesive dielectric layer or an evaporated metal or by additive manufacturing. It is possible to manufacture a waveguide of a small size (30 to 70 μm).

Further embodiments are also directed to a method of guiding THz waves using a photonic integrated circuit as described above, wherein the local functionalization by metallization achieves at least one of the following effects:

-suppressing higher order modes of THz waves;

-coupling or decoupling modes of THz waves;

-converting the mode of the THz wave to another mode.