OPTICAL COMPONENT

Abstract

An optical component serves as a nonlinear photodetector for generating a nonlinear electrical signal. The component comprises a first electrically conductive layer, a second electrically conductive layer and an absorption layer. The absorption layer is arranged between the first and the second electrically conductive layer and has a layer thickness of at least 500 nm. The electrical signal is generated by the component by applying a voltage at the component and irradiating the component with electromagnetic radiation in a first wavelength range (1) with a radiation intensity of less than 10 nW/mm2 and also irradiating the optical component with electromagnetic radiation in a second wavelength range (2) that is different from the first wavelength range (1) and a radiation intensity of less than 100 nW/mm2.

Claims

1. Use of an optical component as a nonlinear photodetector for generating a nonlinear electrical signal, wherein the optical component comprises a first electrically conductive layer, a second electrically conductive layer and an absorption layer, wherein the absorption layer is arranged between the first and the second electrically conductive layer and has a layer thickness of at least 500 nm, wherein the nonlinear electrical signal is generated by the optical component by applying a voltage to the optical component and illuminating the optical component with electromagnetic radiation in a first wavelength range (.sub.1) with a radiation intensity of less than 10 nW/mm.sup.2 and additionally illuminating the optical component with electromagnetic radiation in a second wavelength range (.sub.2) different from the first wavelength range (.sub.1) and with a radiation intensity of less than 100 nW/mm.sup.2, and wherein in a radiation intensity range of less than 100 W/mm.sup.2 a strength of the nonlinear electrical signal is nonlinearly dependent on the applied voltage (U.sub.1) and/or nonlinearly dependent on the radiation intensity of the electromagnetic radiation in the first and/or in the second wavelength range (.sub.1, .sub.2).

2. Use according to claim 1, wherein the strength of the nonlinear electrical signal is greater than a sum of individual electrical signals generated by the optical component, wherein the individual electrical signal is respectively generated by the optical component by applying the voltage (U.sub.1) to the optical component and illuminating the optical component with the electromagnetic radiation in the first wavelength range (.sub.1) with the radiation intensity of less than 10 nW/mm.sup.2 or by applying the voltage (U.sub.1) to the optical component and illuminating the optical component with the electromagnetic radiation in the second wavelength range (.sub.2) different from the first wavelength range (.sub.1) and the radiation intensity of less than 100 nW/mm.sup.2.

3. Use according to claim 2, wherein the sum of the individual electrical signals is multiplicatively amplified as a function of the radiation intensity of the electromagnetic radiation in the first wavelength range (.sub.1) and/or in the second wavelength range (.sub.2).

4. Use according to claim 1, wherein the voltage (U.sub.1) applied to the optical component is between 5 V and +3 V.

5. Use according to claim 1, wherein the electromagnetic radiation in the first wavelength range (.sub.1) and/or the electromagnetic radiation in the second wavelength range (.sub.2) is modulated.

6. Use of an optical component as a frequency mixer for mixing at least two optically induced electrical signals, wherein the optical component comprises a first electrically conductive layer, a second electrically conductive layer and an absorption layer, wherein the absorption layer is arranged between the first and the second electrically conductive layer and has a layer thickness of at least 500 nm, wherein the optical component generates an electrical signal having a sum frequency and/or a difference frequency of a first and a second modulation frequency (f.sub.1, f.sub.2) by applying a voltage (U.sub.1) to the optical component and illuminating the optical component with a first modulated optical signal and a second modulated optical signal, wherein the first modulated optical signal comprises electromagnetic radiation having a first carrier wavelength (.sub.4) and the first modulation frequency (f.sub.1), and wherein the second modulated optical signal comprises electromagnetic radiation having a second carrier wavelength (.sub.6) and the second modulation frequency (f.sub.2).

7. Use according to claim 6, wherein the electrical signal having the sum frequency and/or the difference frequency is generated by the optical component at radiation intensities of the first optical signal and/or the second optical signal of less than 10 nW/mm.sup.2.

8. Use according to claim 6, wherein the first and/or the second carrier wavelength (.sub.4, .sub.6) is in the wavelength range between 350 nm and 850 nm, and/or wherein the first and/or the second modulation frequency (f.sub.1, f.sub.2) is below 100 MHz.

9. Use of an optical component as a sensor element in a photomixing detector for measuring a distance to an object via a time-of-flight method, wherein the optical component comprises a first electrically conductive layer, a second electrically conductive layer and an absorption layer and wherein the absorption layer is arranged between the first and the second electrically conductive layer and has a layer thickness of at least 500 nm,

10. Use according to claim 9, wherein the optical component is illuminated with electromagnetic radiation through the first and/or the second electrically conductive layer.

11. Use according to claim 9, wherein a voltage applied to the optical component is modulated.

12. Use according to claim 9, wherein a) a first side of the absorption layer contacts the first electrically conductive layer and a second side of the absorption layer contacts the second electrically conductive layer, or b) a p-doped layer is disposed between the first side of the absorption layer and the first electrically conductive layer, wherein the p-doped layer contacts the first side of the absorption layer and the first electrically conductive layer, and wherein an n-doped layer is disposed between the second side of the absorption layer and the second electrically conductive layer, wherein the n-doped layer contacts the second side of the absorption layer and the second electrically conductive layer.

13. Use according to claim 9, wherein the absorption layer of the component has an average defect density of at least 10.sup.19 cm.sup.3.

14. Optical component comprising a first electrically conductive layer, a second electrically conductive layer and an absorption layer, wherein the absorption layer is arranged between the first and the second electrically conductive layer and has a layer thickness of at least 500 nm, wherein the absorption layer is made of amorphous hydrogenated silicon and has an average defect density of at least 10.sup.19 cm.sup.3, and wherein a) a first side of the absorption layer contacts the first electrically conductive layer and a second side of the absorption layer contacts the second electrically conductive layer, or b) a p-doped layer is arranged between the first side of the absorption layer and the first electrically conductive layer, wherein the p-doped layer contacts the first side of the absorption layer and the first electrically conductive layer, and an n-doped layer is arranged between the second side of the absorption layer and the second electrically conductive layer, wherein the n-doped layer contacts the second side of the absorption layer and the second electrically conductive layer.

15. Photomixing detector for measuring a distance to an object via a time-of-flight method, comprising a plurality of sensor elements, wherein a sensor element is formed from a component according to claim 14.

16. Photomixing detector according to claim 15, wherein the photomixing detector is configured in such a way that the first electrically conductive layer and the second electrically conductive layer of the component can be illuminated with electromagnetic radiation.

17. Photomixing detector according to claim 15, wherein the plurality of sensor elements are arranged in a three-dimensional array.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0072] In the following, the invention is explained with reference to the drawing based on exemplary embodiments; in the drawing:

[0073] FIG. 1 shows a schematic representation of a component according to an embodiment;

[0074] FIG. 2 shows a block diagram of a component which, according to an embodiment, is used as a nonlinear photodiode;

[0075] FIG. 3 shows a schematic representation of a measurement setup in which a component according to a further embodiment is used as a nonlinear photodiode;

[0076] FIG. 4 shows a schematic representation of a current-voltage curve when using the component as in FIG. 3;

[0077] FIG. 5 shows a schematic representation of an amplification factor as a function of an expected measurement value from FIG. 4;

[0078] FIG. 6 shows a schematic representation of amplitude signals of the component when using the component as in FIG. 3; and

[0079] FIG. 7 shows a schematic representation of a photocurrent and its Fourier transformation of a component used as a frequency mixer according to a further embodiment.

DETAILED DESCRIPTION

[0080] FIG. 1 shows a schematic representation of an optical component 10 according to an embodiment. The component comprises a first electrically conductive layer 12, a second electrically conductive layer 14 and an absorption layer 16, wherein the absorption layer 16 is arranged between the first electrically conductive layer 12 and the second electrically conductive layer 14. In the present case, no further layers are present between the first electrically conductive layer 12 and the second electrically conductive layer 14, so that a first side 18 of the absorption layer 16 contacts the first electrically conductive layer 12 and a second side 20 of the absorption layer 16 contacts the second electrically conductive layer 14. In the present exemplary embodiment the component 10 also comprises a substrate layer 22. The substrate layer 22, which is formed as a glass carrier, contacts a side 24 of the second electrically conductive layer 14 facing away from the absorption layer 16.

[0081] In the present case, the absorption layer 16 has a layer thickness 26 of 500 nm. In addition, the absorption layer 16 has an average defect density of at least 10.sup.19 cm.sup.3. In the embodiment the absorption layer 16 is made of amorphous hydrogenated silicon.

[0082] FIG. 2 shows a block diagram of a component 10 which, according to an embodiment, is used as a nonlinear photodetector 28, in the present embodiment as a nonlinear photodiode 28. The block diagram illustrates the function of the component 10 as a nonlinear photodiode 28 and does not itself represent the component 10. By applying a voltage U.sub.1 to the component 10 and illuminating the component 10 with electromagnetic radiation in a first wavelength range .sub.1, the component 10 generates a first individual electrical signal 30, in the present case a first individual photocurrent 30 (FIG. 2 top). In the present case red light at a wavelength of 633 nm is used for irradiation, wherein the radiation intensity of the light is constant over time. Accordingly, the single photocurrent 30 shows no variation over time 32.

[0083] In addition, by applying the voltage U.sub.1 to the component 10 and illuminating the component 10 with electromagnetic radiation in a second wavelength range .sub.2, the component 10 generates a second individual electrical signal 34, in the present case a second individual photocurrent 34 (FIG. 2 center). In the present case, blue light at a wavelength of 477 nm is used for irradiation, wherein a radiation intensity of the light is modulated. The second individual electrical signal 34 exhibits correspondingly a changing intensity over time 32.

[0084] When the voltage U.sub.1 is applied to the component 10 and the component 10 is illuminated with electromagnetic radiation in the first wavelength range .sub.1 and simultaneously with electromagnetic radiation in the second wavelength range .sub.2, the component 10 generates an electrical signal 36, the magnitude of which is greater than the expected sum of the individual electrical signals 30 and 34. Instead, the strength of the electrical signal 36 is given by multiplying the sum of the individual electrical signals by an radiation intensity-dependent proportionality factor, wherein the proportionality factor is dependent on the radiation intensity of the electromagnetic radiation in the first wavelength range .sub.1 and the radiation intensity of the electromagnetic radiation in the second wavelength range .sub.2.

[0085] Here, the component 10 in FIG. 2 is constructed as shown in FIG. 1, but can also be constructed as shown in FIG. 3 and described below.

[0086] FIG. 3 shows a schematic representation of a measurement setup in which a component 10 according to a further embodiment is used as a nonlinear photodetector 28, in this case as a nonlinear photodiode 28. In the present case, the component 10 comprises five layers, namely the first electrically conductive layer 12, the second electrically conductive layer 14 and the absorption layer 16, which is arranged between the first electrically conductive layer 12 and the second electrically conductive layer 14. In addition, a p-doped layer 40 is arranged between the first side 18 of the absorption layer 16 and the first electrically conductive layer 12, wherein the p-doped layer 40 contacts the first side 18 of the absorption layer 16 and the first electrically conductive layer 12. Likewise, an n-doped layer 38 is disposed between the second side 20 of the absorption layer 16 and the second electrically conductive layer 14, wherein the n-doped layer 38 contacts the second side 20 of the absorption layer 16 and the second electrically conductive layer 14. The first electrically conductive layer 12 and the second electrically conductive layer 14 are in the present case made of indium tin oxide. The absorption layer 16 is made of amorphous, hydrogenated silicon. The layer thickness 26 of the absorption layer 16 is in the present case 1500 nm. The component 10 is disposed on a glass carrier 22, which was glued into a chip housing and contacted with the chip housing (chip housing not shown in FIG. 3). The chip housing was attached to a base and the component 10 was connected to a current/voltage converter module 41. The current/voltage converter module 41 is used to set the voltage. The output of the current/voltage converter module 41 was connected to a multifunction board comprising a digital oscilloscope (not shown in FIG. 3) in order to record measurement data. The multifunction board controls various illumination sources 43in the present case illumination sources 43 that emit electromagnetic radiation in the wavelength ranges .sub.3, .sub.6, .sub.7, .sub.8 and .sub.9. The illumination sources 43 and the component 10 are disposed within an integrating sphere 42. The illumination sources 43, which emit the electromagnetic radiation with the wavelength .sub.6 are in this case a modulated LED, which emits modulated electromagnetic radiation with a wavelength of 633 nm. The other illumination source 43, which emits electromagnetic radiation in the wavelength range .sub.3, is in the present case a laser with a wavelength of 477 nm. The illumination source 43 that emits the electromagnetic radiation with the wave-lengths .sub.7,8,9 is an RGB LED that emits a constant, non-modulated backlight with a wavelength of optionally 450 nm, 520 nm and/or 633 nm.

[0087] FIG. 4 shows exemplary curves of the electrical signal 46 and the individual electrical signals 48, 50 of the component 10 from FIG. 3 as a function of an externally applied voltage 54. The strength 56 of the electrical signal 46 or the individual electrical signals 48, 50, in this case the diode current strength, is plotted on the y-axis in amperes, and the applied voltage 54 is plotted on the x-axis in volts. In the dark casei.e. with no illumination at allthe diode current 56 of the dark current 52 is, as expected, lower than in various illumination situations. In FIG. 3, the voltage-dependent curves of the electrical signal 46 and the individual electrical signals 48, 50 of the component 10 for the following illumination situations are shown in addition to the dark case: [0088] illumination situation for the individual electrical signal 50: illumination with constant background lighting with red LED radiation .sub.9 at 633 nm, [0089] illumination situation for the individual electrical signal 48: illumination with laser radiation .sub.3 at 477 nm, [0090] illumination situation for the electrical signal 46: illumination with constant background lighting with red LED radiation .sub.9 at 633 nm and simultaneously with laser radiation .sub.3 at 477 nm.

[0091] In addition, the vertical line 44 in FIG. 4 exemplarily marks the resulting strength 56 of the electrical signal 46 or the individual electrical signals 48, 50 at a voltage 54 of 1 V. In the illumination situation for the individual electrical signal 50 with red LED a strength 56 of the individual electrical signal of 2.5 A is generated at a voltage of 1 V. In the illumination situation for the individual electrical signal 48 with blue laser, a strength 56 of the individual electrical signal of 3.5 A is generated at a voltage of 1 V.

[0092] In the illumination situation for the electrical signal 46 with red LED and blue laser, a strength 56 of the electrical signal of 63 A is generated at a voltage of 1 V. With photodiodes, the strength 56 of the electrical signal is usually obtained from the sum of the strengths of the individual electrical signals generated by each light color. In the illumination situation for the electrical signal 46 at a voltage 54 of 1 V, the component 10 thus shows a strength 56 of the electrical signal 46 that is approximately 10.5 times higher than the expected sum of the strengths of the individual electrical signals 48, 50 of 6 A, (3.5 A+2.5 A=6 A). In the present case, the dark current 52 is more than an order of magnitude lower than the individual electrical signals 48, 50, so that it plays a negligible role in this consideration.

[0093] FIG. 5a compares the measured electrical signal 46 with the expected sum 46 of the individual electrical signals 48, 50, while FIG. 5b shows the amplification factor 58 between the expected sum 46 of the individual electrical signals 48, 50 and the measured electrical signal 46. The amplification factor 58 can be controlled by the applied voltage 54. In addition, the amplification factor 58 and thus the electrical signal 46 generated by the component 10 is nonlinearly dependent on the applied voltage 54.

[0094] In addition to the applied voltage 54, the strength 56 of the electrical signal of the component 10 also depends on the radiation intensity 60 of the irradiation. FIG. 6 shows exemplary amplitude signals 62, 64, 66 of the electrical signal of the component 10 when illuminated with modulated blue laser radiation .sub.3 at 477 nm as a function of different background illumination situations with constant, non-modulated background illumination with red, green and/or blue LED radiation .sub.7,8,9. The amplitude 57 of the electrical signal of the component 10 is shown on the y-axis in W/mm2. If the spectral sensitivity of the component 10 is known, the amplitude 57 of the electrical signal generated by the component 10 corresponds to the radiation intensity incident on the component 10. The radiation intensity 60 of the constant backlight .sub.7,8,9 is shown on the x-axis in W/mm2. The following illumination situations are shown: [0095] illumination situation for the amplitude signal 62: illumination with modulated blue laser light .sub.3 at 477 nm and with constantly illuminated blue LED radiation .sub.7 at 450 nm with increasing radiation intensity 60, [0096] illumination situation for the amplitude signal 64: illumination with modulated blue laser light .sub.3 at 477 nm and with constantly illuminated green LED radiation .sub.8 at 520 nm with increasing radiation intensity 60, [0097] illumination situation for the amplitude signal 66: illumination with modulated blue laser light .sub.3 at 477 nm and with constantly illuminated red LED radiation .sub.9 at 633 nm with increasing radiation intensity 60.

[0098] In particular in the illumination situations for the amplitude signals 64 and 66, additional exposure of the component 10 to green or red LED radiation generates an amplitude signal 64, 66 of the electrical signal of the component 10, the amplitude 57 of which is nonlinearly dependent on the radiation intensity 60 of the LED radiation .sub.7,8.

[0099] For comparison, FIG. 6 also shows the amplitude signal 68 of a commercially available crystalline silicon phosphor diode (Hamamatsu S2386-8K). The amplitude signal 68 in the commercially available silicon diode caused by the blue laser radiation .sub.3 remains constant and cannot be influenced by the additional LED illumination. Since the amplitude signal 68 of the photodiode does not change, all three measurement curves of the three illumination situations are superimposed, so that only one measurement curve for the amplitude signal 68 can be seen in FIG. 6.

[0100] In contrast, simultaneous illumination of the component 10 with a red LED and a blue laser leads to a massive increase in the amplitude signal 66, the amplitude 57 of which even exceeds the value of the commercially available photodiode.

[0101] FIG. 7 shows in FIG. 7a a schematic representation of a section of a time-dependent electrical signal 72 and in FIG. 7b its Fourier transformation 72 from the component 10 from FIG. 3 used as a frequency mixer in accordance with a further embodiment. In FIG. 7a, the voltage 70 in volts of the digital oscilloscope used to measure the electrical signal 72 is plotted on the y-axis, and the time 32 in seconds is plotted on the x-axis. The component 10 was simultaneously irradiated with modulated blue laser radiation .sub.3 at 477 nm and a modulation frequency of 971 Hz and with modulated red LED radiation .sub.6 at 633 nm and a modulation frequency of 1087 Hz. The electrical signal 72 generated by the component 10 was amplified and transformed to the frequency space 75 by means of a Fast Fourier Transformation. In FIG. 7b, the modulation amplitude 77 in volts is plotted on the y-axis and the frequency 75 in hertz on the x-axis. In addition to the expected fundamental frequencies f.sub.1, f.sub.2 and their harmonics 2.Math.f.sub.1, 2.Math.f.sub.2, a purely passive intrinsic frequency mixing takes place in the component 10, which can be seen in the generation of the difference frequency 76 with the magnitude f.sub.2-f.sub.1 and the sum frequency 78 with the magnitude f.sub.1+f.sub.2.

[0102] For comparison, FIG. 7 also shows an electrical signal 74 and its Fast Fourier Transformation 74 from a commercially available photodiode. In the Fast Fourier Transformation 74 of the electrical signal 74, only the fundamental frequencies f.sub.1, f.sub.2 and their harmonics 2.Math.f.sub.1, 2.Math.f.sub.2 are contained in the commercially available photodiode.

[0103] As used herein, the terms general, generally, and approximately are intended to account for the inherent degree of variance and imprecision that is often attributed to, and often accompanies, any design and manufacturing process, including engineering tolerances, and without deviation from the relevant functionality and intended outcome, such that mathematical precision and exactitude is not implied and, in some instances, is not possible.

[0104] All the features and advantages, including structural details, spatial arrangements and method steps, which follow from the claims, the description and the drawing can be fundamental to the invention both on their own and in different combinations. It is to be understood that the foregoing is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

[0105] As used in this specification and claims, the terms for example, for instance, such as, and like, and the verbs comprising, having, including, and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.

LIST OF REFERENCE NUMERALS

[0106] 10 component [0107] 12 first electrically conductive layer [0108] 14 second electrically conductive layer [0109] 16 absorption layer [0110] 18 first side of absorption layer [0111] 20 second side of absorption layer [0112] 22 substrate layer, glass carrier [0113] 24 side of the second electrically conductive layer facing away from the absorption layer [0114] 26 layer thickness [0115] 28 nonlinear photodiode [0116] 30 individual electrical signal, first individual photocurrent [0117] 32 x-axis, time [0118] 34 individual electrical signal, second individual photocurrent [0119] 36 electrical signal, photocurrent [0120] 38 n-doped layer [0121] 40 p-doped layer [0122] 41 current/voltage converter module [0123] 42 integrating sphere [0124] 43 illumination sources [0125] 44 vertical line [0126] 46 electrical signal, photocurrent [0127] 46 expected photocurrent, sum current from 48 and 50 [0128] 48 individual electrical signal, photocurrent [0129] 50 individual electrical signal, photocurrent [0130] 52 dark current [0131] 54 x-axis, voltage [0132] 56 y-axis, current strength [0133] 57 y-axis, amplitude [0134] 58 amplification factor [0135] 60 radiation intensity [0136] 62 amplitude signal [0137] 64 amplitude signal