Optoelectronic module, method for operating an optoelectronic module and head-mounted display

Abstract

An optoelectronic module (1) comprising at least one semiconductor laser (10) and a photonic chip (20) is described. The semiconductor laser (10) emits a primary electromagnetic radiation which is coupled into the photonic chip (20). The photonic chip (20) comprises at least one first waveguide (210) and at least one optical Bragg reflector (30) having a reflectivity which is modulated by an electrical modulation signal. A secondary electromagnetic radiation is coupled out of the photonic chip (20) by means of at least one second waveguide (220), wherein the secondary electromagnetic radiation has a dominant wavelength which is modulated depending on the electrical modulation signal. Furthermore, a method for operating the optoelectronic module (1) and a head-mounted display comprising the optoelectronic module (1) are provided.

Description

TECHNICAL FIELD

[0001] The present application relates to an optoelectronic module, a method for operating an optoelectronic module and a head-mounted display. It is an object of the present invention to provide an optoelectronic module comprising improved optical properties. SUMMARY

[0002] According to at least one embodiment of the optoelectronic module, the optoelectronic module comprises at least one semiconductor laser and a photonic chip. The semiconductor laser is intended for emitting coherent electromagnetic radiation. The photonic chip preferably comprises a radiation-transmissive material and optical structures, such as waveguides, adapted to manipulate the electromagnetic radiation.

[0003] According to at least one embodiment of the optoelectronic module, the semiconductor laser emits primary electromagnetic radiation. The primary electromagnetic radiation is coupled into the photonic chip. The primary electromagnetic radiation comprises a dominant wavelength. The dominant wavelength of the electromagnetic radiation is the wavelength of the spectrum of the electromagnetic radiation having the highest intensity.

[0004] According to at least one embodiment of the optoelectronic module, the photonic chip comprises at least one first waveguide and at least one optical Bragg reflector having a reflectivity modulated by an electrical modulation signal. The first waveguide transmits the primary electromagnetic radiation from the semiconductor laser to the optical Bragg reflector. The first waveguide can comprise a material that is transmissive for the primary electromagnetic radiation. For example, the first waveguide is at least partially surrounded by a material having a lower refractive index for the primary electromagnetic radiation than the material of the first waveguide itself. Thus, the primary electromagnetic radiation is confined within the waveguide and propagates along the first waveguide.

[0005] According to at least one embodiment of the optoelectronic module, the secondary electromagnetic radiation is coupled out of the photonic chip by means of at least one second waveguide. The second waveguide is arranged downstream of the Bragg reflector. The secondary electromagnetic radiation has a dominant wavelength that is modulated depending on the electrical modulation signal. The modulation of the electrical modulation signal can be any time-dependent change and does not have to be periodic.

[0006] The optoelectronic module preferably emits the secondary electromagnetic radiation at least partially within the spectral range visible to the human eye.

[0007] According to at least one embodiment, the optoelectronic module comprises at least one semiconductor laser and a photonic chip, wherein

[0008] - the semiconductor laser emits primary electromagnetic radiation,

[0009] - the primary electromagnetic radiation is coupled into the photonic chip,

[0010] - the photonic chip comprises at least one first waveguide and at least one optical Bragg reflector having a reflectivity modulated by an electrical modulation signal, and

[0011] - the secondary electromagnetic radiation is coupled out of the photonic chip by means of at least one second waveguide, wherein the secondary electromagnetic radiation has a dominant wavelength that is modulated depending on the electrical modulation signal.

[0012] The optoelectronic module described herein is based, inter alia, on the consideration that semiconductor lasers emit primary electromagnetic radiation with a good beam quality, such that they are particularly suitable for use in head-mounted display units or projection devices. In addition to their good beam quality, semiconductor lasers also have a particularly small extension that approximately corresponds to the emission area of a point light source. This results in an advantageous high brightness, which contributes to the miniaturization of the optical system. However, when semiconductor lasers are used in the visible wavelength range, the observer sometimes perceives undesirable interference effects, for example in the form of speckles. These interference effects produce inhomogeneous illumination and an interfering illumination pattern.

[0013] The optoelectronic module described herein is based, inter alia, on the idea of generating secondary electromagnetic radiation with a varying dominant wavelength. The dominant wavelength of the secondary electromagnetic radiation can be modulated by means of a Bragg reflector, the reflectivity of which can be changed by means of an electrical modulation signal. Furthermore, by superimposing the primary electromagnetic radiation of a plurality of semiconductor lasers, it is possible to generate secondary electromagnetic radiation with an increased secondary spectral bandwidth. By changing the dominant wavelength of the secondary electromagnetic radiation, it is possible to achieve an increase in the spectral bandwidth and a reduction in the coherence length. Smaller coherent radiation advantageously reduces the intensity of any undesirable interference effects. This has the advantage of reducing or eliminating the appearance of speckles.

[0014] According to at least one embodiment of the optoelectronic module, the semiconductor laser has a front face that is covered with an anti-reflection coating. The anti-reflection coating reduces the amount of radiation that is reflected back at the front face and thus cannot be coupled out of the semiconductor laser. Preferably, the front face has a reflectivity of at most 10%, preferably at most 1%, particularly preferably at most 0.001%, for the primary electromagnetic radiation. The low reflectivity of the front face increases the efficiency of the optoelectronic module. Furthermore, if the reflectivity of the front face is reduced, the optical feedback of the semiconductor laser is advantageously controlled by the modulated reflectivity of the Bragg reflector.

[0015] According to at least one embodiment of the optoelectronic module, the primary electromagnetic radiation has a primary spectral bandwidth, and the secondary electromagnetic radiation has a secondary spectral bandwidth that is greater than the primary spectral bandwidth and is controlled by the electrical modulation signal. A higher spectral bandwidth results in a reduction in the coherence of the electromagnetic radiation, thereby reducing or eliminating interfering optical interference effects, such as speckles.

[0016] According to at least one embodiment of the optoelectronic module, the dominant wavelengths of the primary electromagnetic radiation and the secondary electromagnetic radiation are in the visible spectral range. In this document and hereinafter, the visible spectral range shall be defined as the spectral range of wavelengths equal to or greater than 380 nm and equal to or less than 780 nm.

[0017] According to at least one embodiment of the optoelectronic module, the optoelectronic module comprises a plurality of semiconductor lasers, a first waveguide and a Bragg reflector, wherein the first waveguide and the Bragg reflector are assigned to each semiconductor laser. The use of a plurality of semiconductor lasers can increase the power output. Thus, the power output of the optoelectronic module can easily be scaled. By way of example, an optoelectronic module using a plurality of different semiconductor lasers can cover a wide spectral range, wherein each semiconductor laser emits primary electromagnetic radiation having a different dominant wavelength.

[0018] According to at least one embodiment of the optoelectronic module, the semiconductor lasers are monolithically integrated. Preferably, all semiconductor lasers of the optoelectronic module are monolithically integrated. The monolithically integrated element can be, for example, a multi-ridge element comprising a plurality of laser ridges integrated into a single semiconductor body. This facilitates an arrangement of the semiconductor lasers with a small lateral distance from each other. The lateral distance is a distance parallel to the main extension plane of the optoelectronic module.

[0019] According to at least one embodiment of the optoelectronic module, the second waveguides extend to the side of the photonic chip and are arranged at the side of the photonic chip at a lateral distance of less than 10 pm from each other. The arrangement of the second waveguides at the photonic chip with a small lateral distance ensures a particularly small emission area. Such an arrangement is advantageous for the focusing and projection of the secondary electromagnetic radiation.

[0020] According to at least one embodiment of the optoelectronic module, the second waveguides are beam combiners that couple the secondary electromagnetic radiation of the semiconductor lasers into a common waveguide having a common output face. Preferably, the second waveguides are beam combiners that couple the secondary electromagnetic radiation of each semiconductor laser in the common waveguide with the common output face. Such a design allows, for example, the projection of a single RGB pixel by the superposition of the primary electromagnetic radiation of several semiconductor lasers and simplifies the projection of the secondary electromagnetic radiation via optical elements arranged downstream of the common output face.

[0021] According to at least one embodiment of the optoelectronic module, the optoelectronic module comprises at least three different semiconductor lasers, wherein each semiconductor laser emits primary electromagnetic radiation having a different dominant wavelength. For example, one semiconductor laser emits primary electromagnetic radiation having a dominant wavelength in the red spectral region, one semiconductor laser emits primary electromagnetic radiation having a dominant wavelength in the green spectral region, and one semiconductor laser emits primary electromagnetic radiation having a dominant wavelength in the blue spectral region. Such an arrangement allows the manufacture of an RGB optoelectronic module capable of emitting primary electromagnetic radiation having any desired color located within a color triangle spanned by the three different dominant wavelengths.

[0022] According to at least one embodiment of the optoelectronic module, the semiconductor laser is arranged on a photonic chip. The arrangement of the semiconductor laser on the photonic chip facilitates the alignment of the semiconductor laser with respect to the first waveguide. Furthermore, temperature-dependent misalignments can be reduced or avoided and the mechanical stability can be improved.

[0023] According to at least one embodiment of the optoelectronic module, the region extending from the front end face to the first waveguide is filled with a filler material which is transparent to the primary electromagnetic radiation. The filler material can protect the front face from a deteriorating environment. Thus, advantageously, a sealed encapsulation of the front face is not required. For example, the filler material comprises a silicone or an epoxy resin material.

[0024] According to at least one embodiment of the optoelectronic module, the first waveguide, the second waveguide and / or the Bragg reflector are made of one of the following materials: LiNb, ITO, SiN, SiO and a liquid crystal material. Preferably, the first waveguide, the second waveguide and the Bragg reflector are made of one of these materials. The refractive index of ITO depends on the current flowing through it. The refractive index of LiNb, SiN, SiO and a liquid crystal material depends on the voltage applied thereto. Thus, the refractive index of these materials can advantageously be modulated by using an electrical modulation signal.

[0025] According to at least one embodiment of the optoelectronic module, the first waveguide is a single-mode waveguide. A single-mode waveguide only allows the propagation of a transverse mode. Advantageously, this results in a particularly uniform beam intensity profile.

[0026] According to at least one embodiment of the optoelectronic module, the first waveguide tapers from the front face towards the Bragg reflector. The tapering can increase the coupling-in efficiency of the primary electromagnetic radiation generated in the semiconductor laser. For example, the first waveguide has a larger diameter at the end facing the semiconductor laser and the diameter decreases with increasing distance from the semiconductor laser.

[0027] According to at least one embodiment of the optoelectronic module, the photonic chip comprises a substrate made of silicon, glass or sapphire and preferably providing mechanical stability. These substrate materials can be made particularly pure and thus particularly well suited for the growth of additional layers.

[0028] According to at least one embodiment of the optoelectronic module, the photonic chip comprises at least one optical modulator downstream of the Bragg reflector. The optical modulator can be used to modulate the intensity of the secondary electromagnetic radiation. Thus, the pulse length of the secondary electromagnetic radiation can be adjusted. This is particularly advantageous if the semiconductor laser should be operated in continuous mode. Preferably, the optical modulator is a Mach-Zehnder modulator.

[0029] According to at least one embodiment of the optoelectronic module, the photonic chip comprises an optical deflector deflecting the secondary electromagnetic radiation out of a main extension plane of the photonic chip. Preferably, the optical deflector deflects the secondary electromagnetic radiation in a perpendicular direction, particularly preferably in a direction perpendicular to the main extension plane of the photonic chip. For example, the optical deflector is a prism, a grating or a diffractive META optical component. The optical deflector can be arranged directly on the photonic chip. A direct arrangement of the deflector on the photonic chip provides a particularly compact optoelectronic module.

[0030] According to at least one embodiment of the optoelectronic module, each Bragg reflector is electrically connected to a common electrical potential or each Bragg reflector is electrically connected to an individual electrical potential. For example, each Bragg reflector comprises a first electrical terminal which is preferably connected to a different electrical potential. The individually electrically connected Bragg reflectors can be configured to be controlled simultaneously or individually.

[0031] According to at least one embodiment of the optoelectronic module, the front face is tilted with respect to a main extension direction of the semiconductor chip by an angle comprised between 2° and 32°, inclusive, or the coupling-in face of the first waveguide is tilted with respect to a main extension direction of the first waveguide by an angle comprised between 2° and 32°, inclusive. The main extension direction is parallel to a main emission direction of the semiconductor laser. The coupling-in face is an end face of the first waveguide facing the semiconductor laser. Preferably, the primary electromagnetic radiation is mainly coupled into the first waveguide through the coupling-in face.

[0032] By tilting the front face of the semiconductor laser and / or the coupling-in face of the first waveguide, it can be advantageously reduced or prevented that the incident primary electromagnetic radiation is reflected back into the semiconductor laser. For example, a portion of the electromagnetic radiation is reflected back in such a way that it obtains little or no further optical amplification. This helps to suppress any unwanted amplification of side modes.

[0033] Preferably, the front face and / or the coupling-in face are tilted according to the Brewster angle of the primary electromagnetic radiation in order to minimize the reflectivity of the front face and / or the coupling-in face.

[0034] According to at least one embodiment of the optoelectronic module, the photonic chip comprises a photodiode, wherein a portion of the secondary electromagnetic radiation impinges on said photodiode. Preferably, 10% or less of the secondary electromagnetic radiation impinges on the photodiode. The photodiode can be used to monitor the optical power of the semiconductor laser.

[0035] According to at least one embodiment of the optoelectronic module, the photodiode is realized by introducing Ge or Si in the second waveguide.

[0036] According to at least one embodiment of the optoelectronic module, the module comprises a wave plate located downstream of the photonic chip to change the polarization state of the secondary electromagnetic radiation.

[0037] According to at least one embodiment of the optoelectronic module, the module comprises a collimating optics downstream of the photonic chip for collimating the secondary electromagnetic radiation.

[0038] According to at least one embodiment of the optoelectronic module, the photonic chip comprises at least one semiconductor optical amplifier (SOA).

[0039] The aforementioned exemplary embodiments, features and properties of the semiconductor laser relate to optoelectronic modules with a single semiconductor laser and modules with multiple semiconductor lasers. Moreover, the disclosed features and properties can be implemented in all semiconductor lasers or only in some semiconductor lasers.

[0040] The aforementioned exemplary embodiments, features and properties of the first waveguide relate to optoelectronic modules with a single first waveguide and modules with multiple first waveguides. Moreover, the disclosed features and properties can be implemented in all or only in some first waveguides.

[0041] The aforementioned exemplary embodiments, features and properties of the second waveguide relate to optoelectronic modules with a single second waveguide and modules with multiple second waveguides. Moreover, the disclosed features and properties can be implemented in all or only in some second waveguides.

[0042] The aforementioned exemplary embodiments, features and properties of the Bragg reflector relate to optoelectronic modules with a single Bragg reflector and modules with multiple Bragg reflectors. Moreover, the disclosed features and properties can be implemented in all or only in some Bragg reflectors.

[0043] A method for operating an optoelectronic module is also disclosed. The method for operating an optoelectronic module is particularly suitable for operating the optoelectronic modules described in the present invention. This means that all features disclosed in connection with the optoelectronic module are also disclosed for the method for operating an optoelectronic module and vice versa.

[0044] According to at least one embodiment of the method for operating an optoelectronic module, the Bragg reflector modulates the primary wavelength of the secondary electromagnetic radiation with a modulation rate of at least 2 nm / ns. The high modulation rate allows a significant increase in the spectral bandwidth in the secondary electromagnetic radiation without disturbing the perception of the emitted light by a human observer, for example due to flickering.

[0045] According to at least one embodiment of the method for operating an optoelectronic module, the Bragg reflector modulates the primary wavelength of the secondary electromagnetic radiation over a spectral range of at least 10 nm. By varying the primary wavelength of the secondary electromagnetic radiation over a spectral range of at least 10 nm, the coherence length of the secondary electromagnetic radiation is advantageously reduced.

[0046] Also disclosed is a head-mounted display comprising the optoelectronic module described in the present invention. The head-mounted display is especially suitable for use with the optoelectronic module described in the present invention. This means that all features disclosed in connection with the optoelectronic module are also disclosed for the head-mounted display and vice versa. The head-mounted display is for example a near-eye display, a head-up display or a virtual reality headset.

[0047] The optoelectronic module described in the present invention is especially suitable for implementing so-called "smart glasses products" for augmented reality (AR) or virtual reality (VR) units. The optoelectronic module described in the present invention can also be used in various projection systems for displaying image content, for example in glasses, close to the eye or for projecting images directly into the human eye.

[0048] Further advantages and advantageous designs of the optoelectronic module as well as further improvements are obtained by the following exemplary embodiments, which are described in the following in connection with the attached drawings. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 A schematic plan view of the optoelectronic module described in the present invention according to a first exemplary embodiment is shown;

[0050] Figure 2 A schematic plan view of the optoelectronic module described in the present invention according to a second exemplary embodiment is shown;

[0051] Figure 3 A schematic plan view of the optoelectronic module described in the present invention according to a third exemplary embodiment is shown;

[0052] Figure 4 A schematic plan view of the optoelectronic module described in the present invention according to a fourth exemplary embodiment is shown;

[0053] Figure 5 A schematic plan view of the optoelectronic module described in the present invention according to a fifth exemplary embodiment is shown;

[0054] Figure 6 A schematic plan view of the optoelectronic module described in the present invention according to a sixth exemplary embodiment is shown;

[0055] Figure 7 A schematic plan view of the optoelectronic module described in the present invention according to a seventh exemplary embodiment is shown;

[0056] Figure 8 A schematic plan view of the optoelectronic module described in the present invention according to an eighth exemplary embodiment is shown;

[0057] Figure 9 A schematic plan view of the optoelectronic module described in the present invention according to a ninth exemplary embodiment is shown;

[0058] Figure 10 a schematic plan view of an optoelectronic module described in the present invention according to a tenth exemplary embodiment is shown;

[0059] Figure 11 a schematic plan view of an optoelectronic module described in the present invention according to an eleventh exemplary embodiment is shown;

[0060] Figure 12 a schematic plan view of an optoelectronic module described in the present invention according to a twelfth exemplary embodiment is shown;

[0061] Figure 13 a schematic plan view of an optoelectronic module described in the present invention according to a thirteenth exemplary embodiment is shown;

[0062] Figure 14 a schematic plan view of an optoelectronic module described in the present invention according to a fourteenth exemplary embodiment is shown;

[0063] Figure 15 a schematic plan view of an optoelectronic module described in the present invention according to a fifteenth exemplary embodiment is shown;

[0064] Figure 16 a schematic plan view of an optoelectronic module described in the present invention according to a sixteenth exemplary embodiment is shown;

[0065] Figure 17 a schematic plan view of an optoelectronic module described in the present invention according to a seventeenth exemplary embodiment is shown;

[0066] Figure 18 a schematic plan view of an optoelectronic module described in the present invention according to an eighteenth exemplary embodiment is shown;

[0067] Figure 19 a schematic plan view of an optoelectronic module described in the present invention according to a nineteenth exemplary embodiment is shown;

[0068] Figure 20 a schematic plan view of an optoelectronic module described in the present invention according to a twentieth exemplary embodiment is shown. DETAILED DESCRIPTION

[0069] In the drawings, identical, similar, or equivalent elements are labeled with the same reference numerals. The drawings and the elements represented in the drawings are not true to scale with respect to each other. Rather, individual elements can be oversized for better representability and / or understandability.

[0070] Figure 1A schematic plan view of an optoelectronic module 1 according to a first exemplary embodiment is shown. The optoelectronic module 1 comprises a semiconductor laser 10 and a photonic chip 20. The photonic chip 20 has a first waveguide 210, a Bragg reflector 30 and a second waveguide 220.

[0071] The semiconductor laser 10 emits a primary electromagnetic radiation having a primary wavelength through a front face 10A. The front face 10A is a smooth surface of the semiconductor laser 10 facing the photonic chip 20. The first waveguide 210 is made of a material that is transmissive for the primary electromagnetic radiation. The first waveguide 210 has a higher refractive index than the material surrounding the first waveguide 210. The first waveguide 210 extends from a side face 20A of the photonic chip to the Bragg reflector 30. The second waveguide 220 is arranged downstream of the Bragg reflector 30.

[0072] The Bragg reflector 30 comprises a plurality of periodically arranged layers having alternating refractive indices. This results in a reflectivity depending on the refractive indices and the pitch of the periodically arranged layers. The reflectivity of the Bragg reflector 30 can be modulated by a current or a voltage applied to the Bragg reflector 30. A first electrical terminal 41 is arranged on the photonic chip 20 in order to provide an electrical modulation signal to the Bragg reflector 30, which modulates the reflectivity of the Bragg reflector 30.

[0073] The primary electromagnetic radiation is coupled into the first waveguide 210 on the photonic chip 20 and propagates along a main extension direction of the first waveguide 210 to the Bragg reflector 30. Depending on the reflectivity of the Bragg reflector 30 depending on the electrical modulation signal provided via the first electrical terminal 41, a part of the primary electromagnetic radiation is reflected towards the semiconductor laser 10 and a part is transmitted as a secondary electromagnetic radiation to the second waveguide 220 downstream of the Bragg reflector 30.

[0074] Figure 2 A side view of an optoelectronic module 1 according to a second exemplary embodiment is shown. The optoelectronic module 1 comprises a semiconductor laser 10, a photonic chip 20 and a coupling optics 50. The semiconductor laser 10 emits a primary electromagnetic radiation through a front face 10A. The coupling optics 50 is arranged between the semiconductor laser 10 and the photonic chip 20. The primary electromagnetic radiation is guided through the coupling optics 50 to a side face 20A of the photonic chip 20. The coupling optics 50 can comprise e.g. a lens, an optical fiber and an optical connector. Thus, the semiconductor laser 10 does not have to be arranged in direct vicinity of the photonic chip 20.

[0075] The photonic chip 20 has a substrate 21 made of silicon, sapphire or glass, on which the first waveguide 210 and the second waveguide 220 are arranged. The first waveguide 210 and the second waveguide 220 are made of LiNb, ITa, SiN, SiO or a liquid crystal material.

[0076] Figure 3A schematic plan view of a third exemplary embodiment of an optoelectronic module 1 is shown. The optoelectronic module 1 comprises a plurality of monolithically integrated semiconductor lasers 10. All semiconductor lasers 10 are made from one continuous semiconductor body 100.

[0077] The photonic chip 20 comprises a plurality of first waveguides 210, Bragg reflectors 30 and second waveguides 220. The first waveguides 210 and the Bragg reflectors 30 are assigned to each semiconductor laser 10. The second waveguides 220 are assigned to each Bragg reflector 30. By using a plurality of semiconductor lasers 10 the optical output power of the optoelectronic module 1 is increased.

[0078] All Bragg reflectors 30 are connected to a first electrical terminal 41. The reflectivity of the Bragg reflectors 30 can be modulated simultaneously by the first electrical terminal 41.

[0079] Figure 4 A schematic plan view of an optoelectronic module 1 according to a fourth exemplary embodiment is shown. The fourth exemplary embodiment basically corresponds to the third exemplary embodiment. Compared to the third exemplary embodiment, Figure 4 The optoelectronic module 1 in the fourth exemplary embodiment comprises a plurality of semiconductor lasers 10 which are not monolithically integrated. Each semiconductor laser 10 is used to emit primary electromagnetic radiation having a different dominant wavelength.

[0080] The first semiconductor laser 10 is used to emit primary electromagnetic radiation having a dominant wavelength in the red spectral region, the second semiconductor laser 10 is used to emit primary electromagnetic radiation having a dominant wavelength in the green spectral region, the third semiconductor laser 10 is used to emit primary electromagnetic radiation having a dominant wavelength in the blue spectral region and the fourth semiconductor laser 10 is used to emit primary electromagnetic radiation having a dominant wavelength in the orange spectral region. Thus, the emission of all semiconductor lasers 10 can be used to mix electromagnetic radiation to achieve a desired color output.

[0081] In order to increase the optical output power, each semiconductor laser 10 can be replaced by a semiconductor body 100 having a plurality of monolithically integrated semiconductor lasers 10.

[0082] Figure 5 A schematic plan view of an optoelectronic module 1 according to a fifth exemplary embodiment is described. The fifth exemplary embodiment basically corresponds to the first exemplary embodiment. In addition to the first exemplary embodiment, Figure 5 The optoelectronic module 1 in the fifth exemplary embodiment comprises an optical modulator 60 and a second electrical terminal 42. The optical modulator 60 is for example a Mach-Zehnder modulator which is suitable to modulate the secondary electromagnetic radiation in phase and / or intensity. This can advantageously allow a continuous operation mode of the semiconductor laser 10 and increase the maximum modulation frequency of the secondary electromagnetic radiation. The optical modulator 60 can be modulated by an electrical modulation signal applied to the second electrical terminal 42.

[0083] Figure 6 A schematic plan view of an optoelectronic module 1 according to a sixth exemplary embodiment is shown. The sixth exemplary embodiment essentially corresponds to the fifth exemplary embodiment. In addition to the fifth exemplary embodiment, Figure 6 The optoelectronic module in comprises an optical detector 70. The optical detector 70 receives less than 10% of the secondary electromagnetic radiation. The optical detector 70 is for example a photodiode monitoring the optical output power of the semiconductor laser 10. The optical detector 70 can be fabricated by simply introducing germanium or silicon in the photonic chip 20. The current or voltage can be measured at a third electrical terminal 43 connected to the optical detector 70.

[0084] Figure 7 A schematic plan view of an optoelectronic module 1 according to a seventh exemplary embodiment is shown. The optoelectronic module 1 comprises three different semiconductor lasers 10 and a photonic chip 20, wherein each semiconductor laser 10 has a front face 10A. The photonic chip 20 comprises three first waveguides 210, three Bragg reflectors 30 and three second waveguides 220. The first waveguides 210, the Bragg reflectors 30 and the second waveguides 220 are respectively assigned to one of the semiconductor lasers 10. A first electrical terminal 41 is connected to each Bragg reflector 30 to modulate the reflectivity of the Bragg reflector 30 by an electrical modulation signal.

[0085] The secondary electromagnetic radiation is coupled out of the photonic chip 20 by the second waveguides 220. Each second waveguide 220 has an output facet 220A at a side face 20A of the photonic chip 20. The output facets 220A are arranged at a lateral distance D1 from each other. The lateral distance D1 is less than 10 pm. This simplifies further projection and / or collimation of the secondary electromagnetic radiation by optical elements arranged downstream of the photonic chip 20.

[0086] Figure 8 A schematic plan view of an optoelectronic module 1 according to an eighth exemplary embodiment is described. The eighth exemplary embodiment essentially corresponds to the seventh exemplary embodiment. In comparison to the seventh exemplary embodiment, Figure 8 The second waveguides 220 in form a beam combiner coupling the secondary electromagnetic radiation of the semiconductor lasers 10 into a common waveguide having a common output facet 220A. Such a design allows to project a single RGB pixel by superimposing the primary electromagnetic radiation of several semiconductor lasers 10 having different dominant wavelengths. Advantageously, further collimation and / or deflection of such a light source is simplified. Due to the small lateral dimension of the common output facet 220A, it is very similar to a point light source.

[0087] Figure 9 A schematic plan view of an optoelectronic module 1 according to a ninth exemplary embodiment is shown. The ninth exemplary embodiment essentially corresponds to the seventh exemplary embodiment. In addition to the seventh exemplary embodiment,Figure 9 The photonic chip 20 in the optical module 1 comprises a plurality of semiconductor optical amplifiers 80 or SOAs. The semiconductor optical amplifiers 80 are arranged on each second waveguide 220. By means of the semiconductor optical amplifiers 80, the electromagnetic radiation can be amplified to a desired level.

[0088] Each semiconductor optical amplifier 80 is adapted to amplify secondary electromagnetic radiation having a different dominant wavelength. The semiconductor optical amplifiers 80 for blue and green emission are based on InGaN and are grown directly on a sapphire or GaN substrate or on the photonic chip 20. The semiconductor optical amplifiers 80 for amplifying red light emission are constructed as so-called μSOAs, which are grown on a different growth substrate and are subsequently attached to the photonic chip 20.

[0089] Figure 10 A schematic plan view of an optoelectronic module 1 according to a tenth exemplary embodiment is illustrated. The tenth exemplary embodiment essentially corresponds to the ninth exemplary embodiment. In comparison to the ninth exemplary embodiment, the semiconductor laser 10 is arranged on the photonic chip 20. Thus, the photonic chip 20 serves as a mechanically stable mounting platform for the semiconductor laser 10.

[0090] The arrangement of the semiconductor laser 10 on the photonic chip 20 enables a method for manufacturing the optoelectronic module 1, wherein the semiconductor laser 10 is arranged on the photonic chip 20 before the first waveguide 210 is introduced into the photonic chip 20. This allows the first waveguide 210 to be individually aligned with respect to each semiconductor laser 10. The waveguide 210 can be manufactured by using photolithography techniques which can be performed with very high precision. For example, the lateral misalignment of the first waveguide 210 with respect to the semiconductor laser 10 can be less than 1 pm, preferably less than 0.1 pm.

[0091] Figure 11 A schematic plan view of an optoelectronic module 1 according to an eleventh exemplary embodiment is illustrated. The eleventh exemplary embodiment essentially corresponds to the tenth exemplary embodiment. In addition to the tenth exemplary embodiment, the front face 10A of the semiconductor laser 10 is tilted by an angle between 2° and 32° with respect to the main extension direction of the semiconductor laser 10. Furthermore, the first waveguide 210 comprises a coupling-in face 210A which is also tilted by an angle between 2° and 32° with respect to the main extension direction of the first waveguide 210. Preferably, the front face 10A and / or the coupling-in face 210A is tilted by an angle which corresponds to the Brewster angle of the primary electromagnetic radiation in order to minimize the reflectivity.

[0092] Figure 12A schematic plan view of an optoelectronic module 1 according to a twelfth exemplary embodiment is shown. The twelfth exemplary embodiment essentially corresponds to the tenth exemplary embodiment. In addition to the tenth exemplary embodiment, a filling material 90 is arranged between the front face 10A of some semiconductor lasers 10 and the first waveguide 210. The filling material 90 is transmissive for the primary electromagnetic radiation emitted by the semiconductor lasers 10. The filling material 90 protects the front face 10A from a deteriorating environment. Thus, advantageously, a sealed packaging of the front face 10A is not required. The filling material 90 comprises a silicone or an epoxy material. Furthermore, the filling material 90 can comprise a refractive index between the refractive index of the semiconductor lasers 10 and the refractive index of the first waveguide 210 to improve the coupling efficiency of the primary electromagnetic radiation.

[0093] Figure 13 A schematic plan view of an optoelectronic module 1 according to a thirteenth exemplary embodiment is described. The thirteenth exemplary embodiment essentially corresponds to the tenth exemplary embodiment. In addition to the tenth exemplary embodiment, Figure 13 the first waveguide 210 in the

[0094] Figure 14 A schematic plan view of an optoelectronic module 1 according to a fourteenth exemplary embodiment is shown. The fourteenth exemplary embodiment essentially corresponds to the eighth exemplary embodiment. In addition to the eighth exemplary embodiment, an optical element 2 is arranged downstream of the output face 220A of the photonic chip 20. The optical element 2 is, for example, designed to collimate the secondary electromagnetic radiation coupled out from the output face 220A.

[0095] Figure 15 A schematic plan view of an optoelectronic module 1 according to a fifteenth exemplary embodiment is illustrated. The fifteenth exemplary embodiment essentially corresponds to the seventh exemplary embodiment. In addition to the seventh exemplary embodiment, a collimating optics 3 and a plurality of mirrors 4 are arranged downstream of the photonic chip 2. The secondary electromagnetic radiation coupled out from the output face 220A is further collimated by the collimating optics 3 and then deflected by the mirrors 4. The mirrors 4 can be pivoted in at least one axis to achieve a deflection of the collimated secondary electromagnetic radiation in direction. Such an arrangement is particularly suitable for projection devices.

[0096] Figure 16 A schematic plan view of an optoelectronic module 1 according to a sixteenth exemplary embodiment is described. The sixteenth exemplary embodiment essentially corresponds to the eighth exemplary embodiment. In addition to the eighth exemplary embodiment, a collimating optics 3 and a plurality of mirrors 4 are arranged downstream of the photonic chip 20. The second waveguide 220 is formed as a beam combiner coupling the secondary electromagnetic radiation of all semiconductor lasers 10 in a common waveguide.​

[0097] The secondary electromagnetic radiation coupled out of the output face 220A of the common waveguide is further collimated by the collimation optics 3 and then deflected by the mirror 4. The mirror 4 can be pivoted in at least one axis to effect a deflection of the collimated secondary electromagnetic radiation in direction. Such an arrangement is particularly suitable for projection devices. In comparison to the fifteenth exemplary embodiment, the use of a single output face 220A simplifies the collimation of the secondary electromagnetic radiation and enables the use of smaller collimation optics 3.

[0098] Figure 17 A schematic plan view of an optoelectronic module 1 according to a seventeenth exemplary embodiment is shown. The seventeenth exemplary embodiment essentially corresponds to the fifteenth exemplary embodiment. In addition to the fifteenth exemplary embodiment, an increased optical output power and / or a higher display resolution is achieved by increasing the number of semiconductor lasers 10, first waveguides 210, Bragg reflectors 30 and second waveguides 220 (illustrated by dots in the Figure 17 middle).

[0099] Figure 18 A schematic plan view of an optoelectronic module 1 according to an eighteenth exemplary embodiment is shown. The eighteenth exemplary embodiment essentially corresponds to the sixteenth exemplary embodiment. In addition to the sixteenth exemplary embodiment, an increased optical output power and / or a higher display resolution is achieved by increasing the number of semiconductor lasers 10, first waveguides 210, Bragg reflectors 30 and second waveguides 220 (illustrated by dots in the Figure 18 middle).

[0100] Figure 19 A schematic side view of an optoelectronic module 1 according to a nineteenth exemplary embodiment is shown. The optoelectronic module 1 comprises a semiconductor laser 10 and a photonic chip 20. The photonic chip 20 comprises a substrate 21 made of glass, sapphire or silicon. Furthermore, the photonic chip 20 has a first waveguide 210 and a second waveguide 220 arranged on the substrate 21. The semiconductor laser 10 emits a primary electromagnetic radiation through a front face 10A and is arranged on the photonic chip 20. The primary electromagnetic radiation is coupled into the first waveguide 210 through a coupling-in face 210A on a side face 20A of the photonic chip 20.

[0101] The photonic chip 20 comprises an optical deflector 230 which is designed to deflect the secondary electromagnetic radiation out of the main extension plane of the photonic chip 20. Preferably, the optical deflector 230 deflects the secondary electromagnetic radiation perpendicular to the main extension plane of the photonic chip 20. Thus, additional external optical deflection elements downstream of the optoelectronic module 1 can be dispensed with.

[0102] Figure 20A schematic side view of an optoelectronic module 1 according to a twentieth exemplary embodiment is illustrated. The twentieth exemplary embodiment essentially corresponds to the nineteenth exemplary embodiment. In addition to the nineteenth exemplary embodiment, a collimating optic 3 is arranged downstream of the optical deflector 230. The collimating optic 3 can be arranged directly on the photonic chip 20. Advantageously, no further external collimating optic 3 is required downstream of the optoelectronic module 1.

[0103] The present application described is not limited to the description given with reference to the exemplary embodiments. Rather, the present application comprises any novel feature and any combination of features, even if that feature or combination of features is not explicitly indicated in the exemplary embodiments.

[0104] This patent application claims priority to U.S. Patent Application 17 / 028539, the disclosure of which is incorporated by reference into the present application.

[0105] List of reference symbols

[0106] 1 optoelectronic module

[0107] 2 optical element

[0108] 3 collimating optic

[0109] 4 mirror

[0110] 10 semiconductor laser

[0111] 10A front face

[0112] 20 photonic chip

[0113] 20A side face

[0114] 21 substrate

[0115] 30 Bragg reflector

[0116] 41 first electrical terminal

[0117] 42 second electrical terminal

[0118] 43 third electrical terminal

[0119] 50 coupling optic

[0120] 60 optical modulator

[0121] 70 optical detector

[0122] 80 optical amplifier

[0123] 90 filling material

[0124] 100 semiconductor body

[0125] 210 first waveguide

[0126] 210A in-coupling surface

[0127] 220 second waveguide

[0128] 220A out-coupling surface

[0129] 230 optical deflector

[0130] D1 lateral distance

Claims

1. An optoelectronic module (1) comprising at least one semiconductor laser (10) and a photonic chip (20), wherein - The semiconductor laser (10) emits primary electromagnetic radiation, - Couple the primary electromagnetic radiation into the photonic chip (20). - The photonic chip (20) includes at least one first waveguide (210), an electrical terminal, and at least one optical Bragg reflector (30), the at least one optical Bragg reflector having a reflectivity modulated by an electrical modulation signal applied via the electrical terminal, and Primary electromagnetic radiation is coupled into the first waveguide and propagates along the main extension direction of the first waveguide to the Bragg reflector. - Secondary electromagnetic radiation is coupled out of the photonic chip (20) by means of at least one second waveguide (220), wherein, The secondary electromagnetic radiation has a dominant wavelength that depends on the modulation of the electrical modulation signal, and the second waveguide is arranged downstream of the Bragg reflector. - The dominant wavelengths of the primary electromagnetic radiation and the secondary electromagnetic radiation are within the visible spectrum.

2. The photoelectric module (1) according to claim 1, wherein, The semiconductor laser (10) has a front surface (10A) covered with an anti-reflective coating.

3. The photoelectric module (1) according to claim 1 or 2, wherein, The primary electromagnetic radiation has a primary spectral bandwidth, and the secondary electromagnetic radiation has a secondary spectral bandwidth greater than the primary spectral bandwidth and controlled by the electrical modulation signal.

4. The optoelectronic module (1) according to claim 1 or 2, comprising a plurality of semiconductor lasers (10), a first waveguide (210), and a Bragg reflector (30), wherein, The first waveguide (210) and the Bragg reflector (30) are assigned to each semiconductor laser (10).

5. The photoelectric module (1) according to claim 4, wherein, The semiconductor laser (10) is monolithically integrated.

6. The photoelectric module (1) according to claim 4, wherein, The second waveguide (220) extends to the side (20A) of the photonic chip (20) and is arranged to each other at the side (20A) of the photonic chip (20) within a lateral distance (D1) of less than 10 μm.

7. The photoelectric module (1) according to claim 4, wherein, The second waveguide (220) is a beam combiner that couples the secondary electromagnetic radiation of the semiconductor laser (10) into a common waveguide having a common output surface.

8. The optoelectronic module (1) according to claim 4, comprising at least three different semiconductor lasers (10), wherein, Each semiconductor laser (10) emits primary electromagnetic radiation with a different dominant wavelength.

9. The photoelectric module (1) according to claim 2, wherein, One or more of the semiconductor lasers (10) are arranged on the photonic chip (20).

10. The photoelectric module (1) according to claim 9, wherein, The region extending from the front (10A) to the first waveguide (210) is filled with the primary electromagnetic radiation-permeable filling material (90).

11. The photoelectric module (1) according to claim 1 or 2, wherein, One or more of the first waveguides (210), one or more of the second waveguides (220) and / or one or more of the Bragg reflectors (30) are made of one of the following materials: LiNb, ITO, SiN, SiO and liquid crystal materials.

12. The photoelectric module (1) according to claim 1 or 2, wherein, One or more of the first waveguides (210) are single-mode waveguides.

13. The photoelectric module (1) according to claim 2, wherein, One or more of the first waveguides (210) taper gradually from one or more of the front faces (10A) toward one or more of the Bragg reflectors (30).

14. The photoelectric module (1) according to claim 1 or 2, wherein, The photonic chip (20) includes a substrate (21) made of silicon, glass or sapphire.

15. The photoelectric module (1) according to claim 1 or 2, wherein, The photonic chip (20) includes at least one optical modulator (60) downstream of one or more of the Bragg reflectors (30).

16. The photoelectric module (1) according to claim 1 or 2, wherein, The photonic chip (20) includes an optical deflector (230) that deflects the secondary electromagnetic radiation out of the main extension plane of the photonic chip (20).

17. A method for operating the optoelectronic module (1) according to any one of claims 1 to 16, wherein, One or more of the Bragg reflectors (30) modulate the dominant wavelength of the secondary electromagnetic radiation at a modulation rate of at least 2 nm / ns.

18. A method for operating the optoelectronic module (1) according to any one of claims 1 to 16, wherein, One or more of the Bragg reflectors (30) modulate the dominant wavelength of the secondary electromagnetic radiation in a spectral range of at least 10 nm.

19. A head-mounted display comprising an optoelectronic module (1) according to any one of claims 1 to 16.

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