Ultrafast modulated vertical cavity surface emitting laser (VCSEL)

Abstract

To provide a system and a method for an ultrafast modulated vertical cavity surface emitting laser (VCSEL).SOLUTION: An exemplary optical device includes a light source and an electroabsorption modulated laser (EML) based structure over the light source, the electroabsorption modulated laser (EML) based structure includes a grating structure, the grating structure includes a plurality of grating lines, and the grating structure further includes a Pockels material disposed within the grating structure.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] Claiming priority

[0001] This application claims priority to and claims the benefit of U.S. Provisional Patent Application No. 63 / 532,778, filed August 15, 2023, and U.S. Provisional Patent Application No. 63 / 575,281, filed April 5, 2024, each of which is incorporated herein by reference in its entirety.

[0002]

[0002] Aspects of the present disclosure relate to optical communication based solutions. More particularly, certain implementations of the present disclosure relate to methods and systems for implementing and using ultrafast modulated vertical-cavity surface-emitting lasers (VCSELs). [Background technology]

[0003]

[0003] The limitations and drawbacks of conventional diffraction gratings will become apparent to one skilled in the art by comparing such systems with certain aspects of the present disclosure described in other parts of this application with reference to the drawings. Summary of the Invention

[0004]

[0004] Systems and methods are provided for ultrafast modulated vertical-cavity surface-emitting lasers (VCSELs), substantially as shown in and / or described in connection with at least one of the figures, and more fully described in the claims.

[0005]

[0005] These and other advantages, aspects and novel features of the present disclosure, as well as details of illustrative embodiments thereof, will become more fully understood from the following description and drawings. [Brief description of the drawings]

[0006] [Figure 1A] FIG. 1 illustrates an exemplary ultrafast modulated vertical-cavity surface-emitting laser (VCSEL) incorporating Pockels material in an interdigitated lattice for improved performance in accordance with the present disclosure. [Figure 1B] FIG. 1 illustrates an exemplary ultrafast modulated vertical-cavity surface-emitting laser (VCSEL) incorporating Pockels material in an interdigitated lattice for improved performance in accordance with the present disclosure. [Diagram 2]

[0007] FIG. 1 illustrates an example vertical cavity surface emitting laser (VCSEL). [Diagram 3]

[0008] FIG. 1 illustrates an example photonic crystal surface emitting laser (PCSEL). [Figure 4]

[0009] FIG. 1 illustrates an exemplary high order distributed feedback polymer (DFB). [Figure 5A]

[0010] FIG. 1 illustrates an exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) in accordance with the present disclosure. [Figure 5B]

[0011] FIG. 1 illustrates an exemplary three-contact vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) in accordance with the present disclosure. [Figure 5C]

[0012] FIG. 1 illustrates an exemplary four-contact vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) in accordance with the present disclosure. [Figure 6]

[0013] FIG. 2 illustrates an exemplary high contrast grating (HCG) structure according to the present disclosure. [Figure 7]

[0014] 1A-1C illustrate the use of an exemplary high contrast grating (HCG) structure as a reflectance modulator in accordance with the present disclosure. [Figure 8]

[0015] 1A-1C illustrate the use of an exemplary high contrast grating (HCG) structure in wavefront modulation in accordance with the present disclosure. [Figure 9]

[0016] FIG. 1 illustrates the use of an exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) incorporating a high-contrast grating (HCG) with Pockels material as an intensity modulator in accordance with the present disclosure. [Figure 10]

[0017] 1A-1D illustrate different processes for fabricating a vertical-cavity surface-emitting laser (VCSEL) based electroabsorption modulated laser (EML) incorporating a high-contrast grating (HCG) with Pockels material according to the present disclosure. [Figure 11]

[0018] FIG. 1 illustrates dephasing in an exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) incorporating a high-contrast grating (HCG) with Pockels material in accordance with the present disclosure. [Figure 12]

[0019] FIG. 1 illustrates the use of an exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) incorporating a high-contrast grating (HCG) with Pockels material in wavefront modulation according to the present disclosure. [Figure 13]

[0020] FIG. 1 illustrates an exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) incorporating a high-contrast grating (HCG) with Pockels material on the contacts for use in wavefront modulation in accordance with the present disclosure. [Figure 14]

[0021] FIG. 1 illustrates the processing of incident external light in an exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) having a high-contrast grating (HCG) structure incorporating a Pockels material in accordance with the present disclosure. [Figure 15]

[0022] FIG. 1 illustrates an exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) incorporating a high-contrast grating (HCG) with Pockels material for use in polarization modulation in accordance with the present disclosure. [Figure 16]

[0023] 1A-1C illustrate example variations of high contrast grating (HCG) structures with Pockels material according to the present disclosure. [Figure 17]

[0024] FIG. 2 illustrates a first exemplary implementation of an interdigitated electroabsorption modulated laser (EML) based structure according to the present disclosure. [Figure 18]

[0025] FIG. 2 illustrates a second exemplary implementation of an interdigitated electroabsorption modulated laser (EML) based structure according to the present disclosure. [Figure 19]

[0026] FIG. 13 illustrates a third exemplary implementation of an interdigitated electroabsorption modulated laser (EML) based structure according to the present disclosure. [Figure 20]

[0027] 13A-13C illustrate fourth and fifth exemplary implementations of interdigitated electroabsorption modulated laser (EML)-based structures according to the present disclosure. [Figure 21]

[0028] FIG. 13 illustrates a sixth exemplary implementation of an interdigitated electroabsorption modulated laser (EML) based structure in accordance with the present disclosure. [Figure 22]

[0029] FIG. 1 illustrates an exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) incorporating a high-contrast grating (HCG) with Pockels material and dielectric for the gate in accordance with the present disclosure. [Figure 23]

[0030] 1A-1C illustrate exemplary vertical-cavity surface-emitting laser (VCSEL)-based optical devices, one of which incorporates an electroabsorption-modulated laser (EML)-based design. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007]

[0031] 1A-1B show an exemplary ultrafast modulated vertical cavity surface emitting laser (VCSEL) incorporating a Pockels material in an interdigitated lattice for improved performance in accordance with the present disclosure. Referring to FIG. 1A-1B, a vertical cavity surface emitting laser (VCSEL) 100 (or a portion thereof) is shown having an interdigitated lattice for achieving ultrafast modulation.

[0008]

[0032] In this regard, the VCSEL 100 may include a semiconductor laser diode-based structure configured to emit a vertical laser beam emission from a top surface. For example, the VCSEL may include a distributed Bragg reflector (DBR)-based structure configured to act as a mirror parallel to the top surface, with an active region including one or more quantum wells therebetween for laser light generation. A DBR structure may be disposed above the substrate layer and the heat sink layer. The planar DBR mirror may include layers having alternating materials with high and low refractive index (RI).

[0009]

[0033] The thickness of each layer can be set to provide high reflectivity. For example, a thickness of one-quarter of the laser wavelength in the material can provide greater than 99% optical reflectivity. The use of high reflectivity can be used to balance the short axis length of the gain region. In one embodiment, p-type and n-type regions can be embedded between the DBR mirrors, thereby forming a diode junction. This may require more complex semiconductor processing to ensure electrical contact to the active layer / region, but can eliminate power losses in the DBR structure. An example structure of a VCSEL 100 is shown in FIG. 1A.

[0010]

[0034] In accordance with the present disclosure, the performance of the VCSEL may be improved, particularly with respect to the modulation capabilities and / or characteristics of the VCSEL. Specifically, this may be done by incorporating adjustments and / or additions to the structure of the VCSEL, thereby providing performance improvements without adding excessive cost and / or complexity.

[0011]

[0035] In this regard, during operation of a VCSEL, the drive current can be modulated, which in turn modulates the output laser. However, modulation of a VCSEL can sometimes be limited by different factors, including the escape time of photons from the cavity portion of the VCSEL. This reduction in gain can help, but even then it takes some time before the photons can escape. This limits the speed of modulation in a VCSEL. The solution according to the present disclosure allows modulation to be faster than the photon escape time. This can be done, for example, by redirecting the beam in a way that allows the photon escape time to be overcome.

[0012]

[0036] For example, in various embodiments according to the present disclosure, an interdigitated grating can be used in a VCSEL as shown in FIG. 1A. In this regard, the interdigitated grating can include a metal grating filled with a Pockels material, i.e., a material with a high Pockels coefficient material (e.g., organic, Perkinamine™ for KTO, etc.). The Pockels material can be selected based on a given selection criteria, such as ensuring that a high-contrast grating allows the laser beam to be biased as described herein. The use of interdigitated gratings can allow the creation of a "sub-lambda" (or "small relative to the distance to the fiber") arrangement of beams that can exit the top of the modulator by destructive interference in the far field according to the Huygens-Fresnel principle. This will result in high (constructive) or low (destructive) power being coupled into the fiber / far field, such as by varying the applied bias between the two interdigitated gratings. Secondly, this effect can be enhanced by a resonance effect, which can be incorporated into the cavity.

[0013]

[0037] In one exemplary embodiment, a high contrast grating (HCG) based approach can be used. In this regard, the HCG can be used to replace the top distributed Bragg reflector (DBR) layer of a vertical cavity surface emitting laser (VCSEL). In this regard, any suitable high contrast grating (HCG) based design can be used that allows for the realization of the required improvement in modulation speed. In particular, an important consideration in selecting and configuring the high contrast grating (HCG) structure used in the VCSEL to enhance the modulation performance of the VCSEL can be the ability to bias the laser beam, apply gate tension, and the like. For example, as shown in the embodiment illustrated in FIG. 1A, the high contrast grating (HCG) can include etched structures, such as those having "in-plane" periodic or quasi-periodic structures with alternating low and high refractive index (RI) to achieve high "out-of-plane" reflectivity. Also, contacts can be placed on top of the HCG structure (as shown in FIG. 1A). These contacts can effectively function as mirrors. The contacts can include metal or any suitable material. Optionally, the HCG structure may incorporate some DBR material above the active layer / region.

[0014]

[0038] In an exemplary embodiment, the metal array can be used to connect contacts on the surface of the HCG, etc., respectively. This is shown in FIG. 1B, which shows a top view of the metal array disposed on the VCSEL. The metal array can be used as an interdigitated gate with an etched, filled high contrast grating (HCG) of the VCSEL (e.g., DOI:10.1038 / srep40348), with holes filled with Pockels material. In this context, the Pockels material does not need to meet a specific filling criterion (e.g., it may be used to completely fill the holes, but this may not be required). Rather, other factors may be important, such as the overlap between the two different paths and the choice of material used. In this context, the Pockels coefficient of the material should allow the laser beam to be biased, etc., to ensure destructive and constructive interference as described herein. The metal wires of the metal array (i.e., the contacts on the HCG) can be connected to each other and to V2, and can be insulated by a thin insulating layer. Similarly, the Pockels materials (paths) filling the holes in the HCG structure can be connected to each other and to V1. Then, by biasing V2, one half of the path can be dephased with respect to the other half, thereby producing destructive interference.

[0015]

[0039] Notwithstanding the above, the present disclosure is not limited to such designs and solutions based on the present disclosure can be generalized to any suitable shape of the grating, any material suitable for use in the grating, the use (or non-use) of resonance effects to enhance the Pockels effect, etc.

[0016]

[0040] Additionally, while various aspects and features of the present disclosure are illustrated and described based on VCSELs based on implementations, the present disclosure is not limited to VCSELs and similar designs described herein can be used in other types of light emitting devices, such as photonic crystal surface emitting lasers (PCSELs) and high order distributed feedback polymers (DFBs). Exemplary VCSELs, PCSELs and high order DFBs that can be configured to incorporate structural and / or functional modifications based on the present disclosure are shown and described with respect to Figures 2-4.

[0017]

[0041] An exemplary vertical cavity surface emitting laser (VCSEL) is shown in Figure 2. Referring to Figure 2, a vertical cavity surface emitting laser (VCSEL) 200 (or a portion thereof) is shown.

[0018]

[0042] VCSELs are commonly used as light (e.g., laser) sources, especially in implementations such as transceivers (e.g., optical transceivers used in data centers). Traditionally, VCSELs are powered by a direct current (I dc ) and exchange (I ac ) or both.

[0019]

[0043] 2, the VCSEL 200 includes a multiple quantum well (MQW) layer that serves as a gain medium sandwiched between two mirrors (e.g., distributed Bragg reflector (DBR) layers). The VCSEL 200 also includes contacts, such as on a top surface of the upper mirror layer and / or on a bottom surface of the VCSEL 200. The contacts may include, for example, a metallic material.

[0020]

[0044] An exemplary photonic crystal surface-emitting laser (PCSEL) is shown in Figure 3. Referring to Figure 3, a photonic crystal surface-emitting laser (PCSEL) 300 (or a portion thereof) is shown.

[0021]

[0045] PCSELs are commonly used as light (e.g., laser) sources and are traditionally powered by direct current (I dc ) and exchange (I ac) or both.

[0046] 3, the PCSEL 300 includes a multiple quantum well (MQW) layer that serves as a gain medium sandwiched between a mirror (e.g., a distributed Bragg reflector (DBR)) layer on the bottom surface and a photonic crystal layer on top of the MQW layer. The PCSEL 300 also includes contacts, such as on a top surface of the upper mirror layer and / or on a bottom surface of the PCSEL 300. The contacts may include, for example, a metallic material, or the like.

[0022]

[0047] An exemplary high order distributed feedback polymer (DFB) is shown in Figure 4. Referring to Figure 4, a high order distributed feedback polymer (DFB) 400 (or a portion thereof) is shown.

[0048] High-order DFBs are commonly used as light (e.g. laser) sources and are traditionally used with direct current (I dc ) and exchange (I ac ) or both.

[0023]

[0049] 4, the high-order DFB 400 includes a multiple quantum well (MQW) layer acting as a gain medium sandwiched between a mirror (e.g., a distributed Bragg reflector (DBR)) layer on the bottom surface and a high-order lattice layer on top of the MQW layer. The high-order DFB 400 also includes contacts, such as on the top surface of the upper mirror layer and / or on the bottom surface of the high-order DFB 400. The contacts may include, for example, a metallic material.

[0024]

[0050] Since the solution according to the present disclosure is also applicable to bottom emission, each of the three different types of optical devices (VCSEL, PCSEL and high-order DFB) shown in Figures 2-4 are shown with bottom emission.

[0025]

[0051] An exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) according to the present disclosure is shown in Figure 5A. Referring to Figure 5A, a vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) 500 (or a portion thereof) is shown.

[0026]

[0052] The VCSEL-EML 500 includes a multiple quantum well (MQW) layer serving as a gain medium sandwiched between two mirrors (e.g., distributed Bragg reflector (DBR) layers) and has an electroabsorption modulated laser (EML)-based structure on top of the top mirror layer. The VCSEL-EML 500 may also include contacts, such as on the top surface of the EML-based structure, on the top surface of the top mirror layer, and / or on a bottom surface of the VCSEL-EML 500. The contacts may include, for example, a metallic material.

[0027]

[0053] VCSELs are commonly used as light (e.g., laser) sources, especially in implementations such as transceivers (e.g., optical transceivers used in data centers). Traditionally, direct-drive or DAC / DC-based VCSELs are used. However, such directly modulated VCSELs are approaching a bandwidth (BW) bottleneck between the electrical and optical bandwidths.

[0028]

[0054] Thus, a VCSEL-EML device is used in which an EML-based structure is added for use in processing at least a portion of the modulation performed in the VCSEL. In this regard, during exemplary operation of the VCSEL-EML, a modulation voltage can be applied across the EML-based structure, and then a current is provided to drive the entire device. For example, the device can be driven using a time-varying voltage, allowing for digitized-based driving (e.g., based on a voltage on or off), such as a digital signal that modulates the output optical signal. Alternatively, the device can be driven by a direct current (DC) so that it is always on. For example, as shown in FIG. 5A, the VCSEL-EML 500 uses a V ac is used to drive the device (as a whole), while I dc is used.

[0029]

[0055] According to the present disclosure, the performance of a VCSEL-EML (e.g., VCSEL-EML500) can be improved and / or optimized by modifying the EML-based structure, particularly as used herein. For example, the VCSEL-EML can be modified to implement new modulation schemes, such as by incorporating a vertical EML that uses and / or exploits the Pockels effect. In this regard, in such implementations, the VCSEL can be used as a continuous wave (CW) light source with the proposed EML-based structure monolithically implemented on the top mirror (e.g., DBR) layer of the VCSEL. Also, the EML can be modified to improve the performance of the EML and the entire device, particularly by incorporating a Pockels material to exploit the Pockels effect.

[0030]

[0056] In this context, the Pockels effect is the direction-dependent linear variation of the refractive index (RI) of an optical medium that occurs in response to the application of an electric field. The refractive index of an optical medium is a dimensionless number that gives a measure of the medium's ability to bend light. In other words, the refractive index is a measure of the speed of light in the material. Thus, in various implementations, Pockels materials are added to EML-based structures to allow for modulating light based on the refractive index (RI) of the material (e.g., by controlling the application of a voltage across the Pockels material), thereby affecting the behavior of a light beam when applied to an EML-based structure.

[0031]

[0057] Such an approach can be made material independent, for example by using an adaptation of the bias scheme on top of the EML-based structure instead. In this regard, the Pockels material used in the EML can be adaptively selected and / or adapted to ensure that a particular performance criterion (e.g., determined in terms of a desired or required RI) is met, as described herein. Also, in many cases, the applied Pockels material can be used in conjunction with a bias scheme (applicable to the EML-based structure), where the bias scheme is adapted for the desired modulation function.

[0032]

[0058] For example, as shown in FIG. 5A, the VCSEL-EML 500 is implemented as an integrated 3-contact VCSEL with the laser DC drive separated from the modulation drive. This allows for the use of the EML electronics scheme with direct driving of the modulation section. The incorporation of Pockels materials into the EML-based structure allows for performance enhancements based on adaptive exploitation of the Pockels effect. Specifically, Pockels materials can be used to enable the formation and / or use of sub-wavelength patterns to enhance the Pockels effect.

[0033]

[0059] In various exemplary implementations, the EML can incorporate gratings configured to support modulation functions, and these gratings incorporate Pockels materials to exploit the Pockels effect. For example, in some implementations, the incorporation of Pockels materials can be done in conjunction with high contrast gratings (HCGs). In this regard, the use of high contrast gratings (HCGs) can be desirable because they can provide various advantages, such as limited optical losses (e.g., <<3 dB), the ability to use high Pockels materials, and the ability to use readily available simulation capabilities of HCGs. In some cases, etched structures (e.g., 50 nm to 100 nm wide and 200 nm to 400 nm deep) in high refractive index materials can be used.

[0034]

[0060] Depending on the configuration, the proposed EML-based structures may be used to provide various modulation functions: for example, the EML can be used to modulate the launch power (intensity or amplitude modulation), to modulate the deflection of the beam, e.g., the launch coupling into a fiber (wavefront modulation), and / or to modulate the polarization of the beam (polarization modulation).

[0035]

[0061] In some cases, the proposed EML-based structure can be configured to meet specific performance criteria. For example, EML meets the goal V Π<<5V. To meet such performance criteria, EML-based structures may need to be designed and / or configured accordingly. For example, such target V Π Ensuring that θ is satisfied may require optical field enhancement in, for example, a Pockels material.

[0036]

[0062] In some cases, the proposed EML-based structures may be used in other applications, such as for beam steering (e.g., as ultrafast spatial light modulators), to provide 100 Gbps components (e.g., passive optical network (PON) elements (e.g., on fiber chips, vertical modulators / couplers, etc.), MUX / DEMUX functions, etc.).

[0037]

[0063] In some implementations, the proposed EML-based structure can be used with a photonic crystal surface-emitting laser (PCSEL) light source (rather than a VCSEL). The use of a PCSEL as a light source can be advantageous, for example to optimize the benefits of HCG design possibilities. In this regard, a PCSEL may be an optimal light source since it is an essentially single mode device, which can allow for utilizing the full potential of the high-Q resonances of the HCG and / or can allow for uniform illumination of the HCG (thereby allowing for the avoidance of undesirable finite size effects of the HCG).

[0038]

[0064] An exemplary three-contact vertical cavity surface emitting laser (VCSEL)-based electroabsorption modulated laser (EML) according to the present disclosure is shown in FIG. 5B. Referring to FIG. 5B, a vertical cavity surface emitting laser (VCSEL)-based electroabsorption modulated laser (EML) 520 (or a portion thereof) is shown.

[0039]

[0065] In this regard, the VCSEL-EML 520 may be substantially similar to and operate substantially similarly to the VCSEL-EML 500 of FIG. 5A. Specifically, the VCSEL-EML 520 includes an electroabsorption modulated laser (EML)-based structure on a generic vertical emitting laser structure. The generic vertical emitting laser structure may include any suitable structure that can be configured to enable the laser to emit light in a vertical direction. For example, the generic vertical emitting laser structure may have a structure similar to the corresponding structure in the VCSEL-EML 500 of FIG. 5A, and thus may include a multiple quantum well (MQW) layer that serves as a gain medium sandwiched between two mirrors (e.g., a distributed Bragg reflector (DBR) layer).

[0040]

[0066] The VCSEL-EML 520 may also include contacts on a top surface of the EML-based structure, on a top surface of the generic vertical emitting laser structure, and / or on a bottom surface of the generic vertical emitting laser structure, etc. The contacts may include, for example, a metallic material, etc.

[0041]

[0067] The VCSEL-EML 520 represents an alternative design that uses three contacts. For example, in the embodiment shown in FIG. 3B, the three contacts may correspond to a contact on the top surface of the EML-based structure, a contact on the top surface of the generic vertical emitting laser structure, and a contact on the bottom surface of the generic vertical emitting laser structure. These three contacts are I dc and / or V ac It is driven using

[0042]

[0068] An exemplary four-contact vertical cavity surface emitting laser (VCSEL)-based electroabsorption modulated laser (EML) according to the present disclosure is shown in FIG 5C. Referring to FIG 5B, a vertical cavity surface emitting laser (VCSEL)-based electroabsorption modulated laser (EML) 540 (or a portion thereof) is shown.

[0043]

[0069] In this regard, the VCSEL-EML 540 may be substantially similar to the VCSEL-EML 500 of FIG. 5A and may operate substantially similarly. Specifically, the VCSEL-EML 540 includes an electroabsorption modulated laser (EML)-based structure on top of a generic vertically emitting laser structure with an electrically insulating layer sandwiched therebetween. The generic vertically emitting laser structure may include any suitable structure that can be configured to emit the laser vertically. For example, the generic vertically emitting laser structure may have a structure similar to the corresponding structure of the VCSEL-EML 500 of FIG. 5A and thus may include a multiple quantum well (MQW) layer serving as a gain medium sandwiched between two mirrors (e.g., a distributed Bragg reflector (DBR) layer).

[0044]

[0070] The VCSEL-EML 540 may also include contacts on a top surface of the EML-based structure, on a top surface of the generic vertical emitting laser structure, and / or on a bottom surface of the generic vertical emitting laser structure, etc. The contacts may include, for example, a metallic material, etc.

[0045]

[0071] The VCSEL-EML 540 represents an alternative design that uses four contacts. For example, in the implementation shown in FIG. 5C, the four contacts may correspond to a contact on the top surface of the EML-based structure, a contact on the top surface of the generic vertical emitting laser structure, and a contact on the bottom surface of the generic vertical emitting laser structure, respectively, with the contacts on the top surface of the EML-based structure being arranged into two separate groups of contacts as shown in FIG. 5. These four contacts are I dc and / or V ac It is driven using

[0046]

[0072] An exemplary high contrast grating (HCG) structure according to the present disclosure is shown in Figure 6. Referring to Figure 6, a vertical cavity surface emitting laser (VCSEL) 600 incorporating a high contrast grating (HCG) 610 is shown.

[0047]

[0073] The VCSEL 600 includes two mirrors with an active layer (e.g., MQW) sandwiched between them, with the top mirror incorporating the HCG 610. The bottom and top mirrors combine with the active layer along with a grating structure to form the laser cavity.

[0048]

[0074] As mentioned above, in some cases, high contrast gratings (e.g., HCG610) may be used in vertical cavity surface emitting laser (VCSEL) based electroabsorption modulated lasers (EMLs) implemented according to the present disclosure, with HCGs being used in particular to facilitate and / or support the modulation function performed by the EML based structures in the proposed EML based structures. In this regard, the gratings incorporate grating features having gaps therebetween, and may be sized according to the height of the grating features (dimension h), the width of the grating features (dimension a), the thickness of the contacts above the grating features (dimension h M ), the period of the lattice features, i.e., the distance between identical points in consecutive lattice features (dimension d), and the total depth of the gap (dimensions h and h when a contact is placed over the lattice feature shown in Figure 6). M The method may be characterized by parameters such as:

[0049]

[0075] High contrast gratings such as HCG610 can incorporate grating features with sub-wavelength dimensions and can have strong refractive index contrast (e.g., air refractive index of the grating >1.7). High contrast can be achieved by gaps that can be filled (e.g., by air with a very low RI), resulting in high contrast between the gaps and the grating structure features. In this regard, the grating features are tall (and therefore have deep gaps). In other words, the gaps can typically be deeper than they are wide so that a specular reflection effect is observed.

[0050]

[0076] High contrast gratings such as HCG 610 can exhibit two modes: reflection (mode 0) and transmission (mode 2), where an incident wave (applied from below to the HCG after propagating from within the device, i.e., through the underlying substrate) is reflected in mode 0 and passes through (as an outgoing wave) in mode 2, as shown in FIG. 6 (graph 620). In this regard, the reflection / transmission modes can couple with each other and with plane waves. The transmission mode (mode 2) can be determined by destructive interference between the grating features. For example, for a 50 / 50 formed coupling (e.g., HCG geometry), the destructive interference can be determined by Δβ / λ=Π.

[0051]

[0077] In various cases, high-contrast gratings may have two basic features: 1) only a few modes can be excited and can be extracted from the outside as "plane waves" and 2) the modes can be squeezed in space and obtain higher transverse momentum. In feature 1, the HCG blocks high spatial frequency components. Therefore, a two- or three-mode description of the HCG is sufficient to predict the general behavior, and other modes are usually evanescent. In this context, such other modes can exist below the light cone and may enter the second order when estimating the reflection / transmission properties at the HCG interface with air. In feature 2, the propagation constant is reduced and destructive interference between modes can be obtained (e.g. for structures at <~ wavelengths).

[0052]

[0078] High contrast gratings may exhibit different performance characteristics in different wavelength ranges. For example, for sub-wavelength dimensions, only one mode may exist in the structure, and Fabry-Perot (FP) nodes / antinodes may be seen as the thickness of the HCG increases. For super-wavelength dimensions, many modes may exist, and there is a periodic recovery of the input signal in a manner / pattern similar to the Talbot effect. There may be only a few modes between these two ranges. Also, at certain positions, two modes may co-resonate within the HCG. For example, at 2nΠ phase difference, energy is trapped inside the HCG, and there may be a large electric field enhancement (e.g., 1e3), which appears as an anti-crossing. At (2n+1)Π phase difference, some of this energy may be reflected from the HCG.

[0053]

[0079] In addition to their use in creating optical resonance in devices such as VCSELs, high contrast gratings can also be used in other applications such as beam manipulation (e.g., lenses, polarization, diffractive elements), waveguiding (e.g., MMIs, spot size converters, etc.), high broadband reflection, broadband anti-reflection coatings, nonlinear optics, biosensing, and chemical sensing.

[0054]

[0080] In implementations consistent with the present disclosure, a Pockels material can be incorporated into the HCG structure, for example, by using the Pockels material to fill at least a portion of the gaps between the grating features and / or to form the grating features (e.g., having contacts thereon). In this regard, the use of the Pockels material can improve the operation of the HCG structure, particularly with respect to the modulation capabilities of the HCG structure, as will be described in further detail below.

[0055]

[0081] The use of an exemplary high contrast grating (HCG) structure as a reflectance modulator according to the present disclosure is illustrated in Figure 7. Referring to Figure 7, a vertical cavity surface emitting laser (VCSEL) 700 incorporating a high contrast grating (HCG) is shown.

[0056]

[0082] The VCSEL 700 may represent a vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) implemented according to the present disclosure, where the HCG is used in the proposed EML-based structure to facilitate and / or support the modulation function performed by the EML. An example application of the HCG is shown in FIG. 7, namely, the use of the HCG in an EML-based structure operating as a reflectivity modulator.

[0057]

[0083] Such reflectance modulators can exhibit high electric field enhancement. For example, a silicon-based grating can produce a “V Π "There can be a 30-fold electric field enhancement. Also, in some cases, various aspects or features can be modified to further enhance performance. For example, in some cases, dimerized HCG (rather than regular HCG) can be used for better control. Also, different materials may be used in the lattice structure, such as by using BaTiO3 or organic materials instead of silicon, which may provide greater tunability.

[0058]

[0084] In an exemplary operation of such a reflectance modulator, for a beam propagating through the HCG (grating), if the beam has the right wavelength (and / or the grating is properly designed), there is a significant enhancement of the optical field. The electric field of the incident beam between the grating is larger compared to the electric field of the incident beam before passing through the grating. Similarly, for beams with the right wavelength, the structure becomes reflective. The resonant frequency (where the beam is reflected rather than passed through and modulated) can be controlled by adjusting the voltage applied to the grating. This is illustrated in an exemplary usage scenario 710 of the VCSEL 700 and depicted in graph 720 showing the transmittance as a function of wavelength.

[0059]

[0085] In implementations based on the present disclosure, reflectivity modulation can be further enhanced by incorporating Pockels material within the HCG structure, for example within the gaps between features (etches), using Pockels material to form features (with contacts thereon), etc.

[0060]

[0086] The use of an exemplary high contrast grating (HCG) structure in wavefront modulation according to the present disclosure is illustrated in Figure 8. Referring to Figure 8, a high contrast grating (HCG) 800 is shown.

[0061]

[0087] The HCG 800 can be used with a vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) implemented according to the present disclosure, where the HCG is used in the proposed EML-based structure to enhance and / or support the modulation function performed by the EML. Figure 8 is an example application of the HCG, i.e., the use of the HCG 800 in an EML-based structure operating as a wavefront modulator.

[0062]

[0088] In this regard, in an exemplary operation of such a wavefront modulator, the HCG can be biased by group, i.e., by set of gratings in the HCG structure, as shown in FIG. 8. Such biasing allows the beam to be deflected at discrete angles. The angles can be defined, for example, by the discrete geometry of the HCG structure. In some cases, the angle of deflection (or diffraction of an externally incident beam) can be adjustable, as shown in FIG. 8 (810) and represented by graph 820 showing a normalized angular intensity distribution based on the use of an exemplary proposed EML-based structure.

[0063]

[0089] In implementations based on the present disclosure, wavefront modulation can be further enhanced by incorporating Pockels material into the HCG structure, for example in the gaps between features (etches), using Pockels material to form features (with contacts thereon), etc.

[0064]

[0090] An exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) incorporating a high-contrast grating (HCG) with a Pockels material according to the present disclosure is shown for use as an intensity modulator in Figure 9. Referring to Figure 9, a high-contrast grating (HCG) 900 is shown.

[0065]

[0091] As mentioned above, in some cases, high contrast gratings can be used in vertical cavity surface emitting laser (VCSEL) based electroabsorption modulated lasers (EMLs) implemented in accordance with the present disclosure, and HCG900 is configured for such use in the proposed EML-based structures to facilitate and / or support the modulation functions performed by the EML-based structures.

[0066]

[0092] As shown in FIG. 9, the HCG 900 can incorporate two contacts that can be interleaved (as shown in a plan view, i.e., looking down on the top of the structure), thereby forming an interdigitated grid of gates. The HCG 900 can also include a Pockels material. In this regard, in the embodiment shown in FIG. 9, the Pockels material is used to fill the gap between the two contacts. However, the disclosure is not limited to such an approach, and thus the placement of the contacts and / or the placement of the Pockels material may be done in any suitable manner. For example, an alternative design in which the contacts are positioned on top of the Pockels material is shown in FIG. 13.

[0067]

[0093] Separate voltages (V1 and V2) can be applied to the two contacts to produce a particular bias in the HCG. In this regard, the interdigitated lattice allows for the creation of an electric field through the Pockels material between two different lattice elements (corresponding to the locations of the contacts V1 and V2). The two contacts are not (necessarily) made of different materials; rather, the application of different voltages to the contacts produces different electric fields.

[0068]

[0094] The interdigitated bias grating creates a transverse electric field as shown in Figure 9, i.e., due to the interdigitation, the direction of the electric field across the Pockels material can alternate (as shown). The interdigitated bias grating can also periodically change the refractive index (RI) of the entire HCG structure. In this regard, the RI can be changed in the grating by changing the electric field applied across the Pockels material. Since the RI governs the speed of light, changing the RI changes the phase of the light passing through the grating.

[0069]

[0095] The use of Pockels materials can further enhance performance. For example, low V Π To maintain , the Pockels material (and the corresponding Pockels effect) can be used together with the resonant enhancement (from the grating features). In this regard, the Pockels effect itself may be too small to achieve the desired Π phase change, and therefore the resonance may also be used to achieve the required optical field enhancement. Thus, the realization of the desired Pockels effect can be achieved not by increasing the voltage, but by providing a resonant field enhancement. In other words, the resonance from the grating structure can be used to increase the strength of the optical field, thereby enhancing the Pockels effect (without increasing the voltage applied to the grating).

[0070]

[0096] As mentioned above, the use of HCG in the proposed EML-based structure allows for a low target V Π (e.g., <<5V). In this regard, in the absence of cavity or resonance effects, the tilt angle (θ) can be found using the following equation:

[0071]

number

[0072] where h is the height of the material and d is the grating period. Without the electric field enhancement, the effect may be too small.

[0097] For example, n=2, ΔV=5V, γ 33For θ = 700 pm / V, h = 1 um, and d = 100 nm, sin(Θ) = 1.4e-2. Other means such as vertical DBR cavities, plasmon resonances from gratings, and high contrast gratings (HCGs) may be required to enhance by about 10 to 100 times. In this context, HCGs can be used to achieve a local × 10 3 This can result in electric field enhancement. Compared to optical microcavities, the electric field (E) used in HCG is similar, but the applied bias is much lower (due to the extremely small distance between the electrodes). Nevertheless, in some cases, HCG can be combined with a DBR cavity for even higher nonlinear effects.

[0073]

[0098] An EML-based structure incorporating HCG900 (e.g., as used in VCSEL-EML devices) can function as an intensity (amplitude) modulator, as shown in Figure 6. However, EML-based structures can also be used to provide other functions, such as wavefront modulation, reflectivity modulation, etc.

[0074]

[0099] In one implementation, an EML-based structure (e.g., as used in VCSEL-EML devices) with an HCG incorporating a Pockels material can be used to provide polarization rotation. In this context, the grating features are essentially linear polarizers and therefore will selectively transmit a light beam having polarization in a particular direction (e.g., the x-direction). The structure can be configured to provide polarization rotation that can be used, for example, to block the beam. The use of such polarization rotation can be used in conjunction with or instead of the use of index-related features.

[0075]

[0100] 10 shows different processes for fabricating a vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) incorporating a high-contrast grating (HCG) with Pockels material according to the present disclosure. Referring to FIG. 10, two different fabrication processes 1000 and 1010 are shown for fabricating a VCSEL-EML with a high-contrast grating (HCG) structure with Pockels material.

[0076]

[0101] In this regard, different methods (processes) can be used in the fabrication of optical devices (e.g., VCSELs) having EML-based structures incorporating HCGs with Pockels material, and the present disclosure is not limited to a particular method or approach. The fabrication methods can differ with respect to the deposition technique used in applying the Pockels material. The fabrication methods can also be influenced by the design of the HCG (e.g., with respect to the arrangement of contacts used in the HCG). For example, when using interdigitated contacts, there may be several physical implementations that can be used, as described in further detail below, and the fabrication methods may need to be adapted to take into account the use of such configurations. Thus, the fabrication methods can differ in the manner in which the Pockels material is applied in the particular grating (HCG) structure used.

[0077]

[0102] For example, the process can be "top-bottom" or "bottom-up" depending on the deposition technique of the Pockels material as shown in FIG. 10. In this regard, in process 1000, a layer of Pockels material is first placed on an insulating layer. Then, the Pockels material layer is etched to form spaces for the contacts, and then the contacts are added. In process 1010, the contacts are first added on the insulating layer with spaces between them based on a predetermined interleaving that includes spaces between the contacts. Then, a layer of Pockels material is deposited or formed in the spaces between the contacts.

[0078]

[0103] In some cases, the process used to fabricate the VCSEL-EML can be configured to meet certain criteria (e.g., dimensions in the final structure, such as depth of about 250 nm, openings in the range of 50 nm to 100 nm, etc.) Thus, fabrication of the HCG structure requires the addition and / or deposition of about 250 nm on top of the HCG to form only in certain areas (voids in a bottom-up process) or over the entire surface, with some of the added layer being removed later (by an etch stop).

[0079]

[0104] The implementation of the Pockels material, i.e., adding the Pockels material to the lattice structure, can be done in a variety of ways, and the present disclosure is not limited to any particular approach, and therefore any suitable approach can be used. For example, the Pockels material may be implemented at the wafer bonding level by processing (e.g., using BTO, Li.Nb., BaTiO3, etc.). The Pockels material may be implemented at or near the end of the process (e.g., using an organic, BTO-based suspension, etc.).

[0080]

[0105] 11 illustrates dephasing in an exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) incorporating a high-contrast grating (HCG) with Pockels material according to the present disclosure. Referring to FIG. 11, a VCSEL-EML 1100 is shown incorporating an HCG structure with Pockels material in the gap between the contacts. The VCSEL-EML 1100 may be substantially similar to the VCSEL-EML 900 described with respect to FIG. 9.

[0081]

[0106] Dephasing in a VCSEL such as the VCSEL-EML1100 is shown in Figure 11. In this context, dephasing can occur as a result of a voltage difference between the interdigitated gates, which can cause a periodic change in the refractive index (RI) within the structure. For example, the RI can be altered by controlling (setting and / or varying) the electric field applied across the Pockels material. Since RI governs the speed of light, altering the RI changes the phase of the light passing through the grating.

[0082]

[0107] In a VCSEL incorporating two contacts (e.g., VCSEL-EML1100), dephasing can be achieved by adjusting the voltages applied to the two contacts. In this regard, when the voltages at the two contacts are the same (i.e., when V1=V2), the contacts are in phase and therefore the interference is constructive in the vertical direction, whereas when the voltages are not the same (i.e., V1≠V2), a periodic change in the refractive index can be created, resulting in destructive interference in the vertical direction and therefore dephasing of the contact (gate).

[0083]

[0108] An exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) incorporating a high-contrast grating (HCG) with Pockels material according to the present disclosure is shown for use in wavefront modulation in Figure 12. Referring to Figure 12, a VCSEL-EML 1200 is shown incorporating an HCG structure with Pockels material in the gap between the contacts.

[0084]

[0109] The VCSEL-EML 1200 may be substantially similar to the VCSEL-EML 900 described with respect to FIG. 9. As shown in FIG. 12, the VCSEL-EML 1200 may function as a wavefront modulator. In this regard, the refractive index (RI) may be altered based on varying the electric field applied to different contacts across the Pockels material. As discussed above, RI governs the speed of light, and therefore altering the RI changes the phase of the light passing through the grating. Thus, the contacts will be in phase when the Pockels material is subjected to the same voltage and out of phase when the voltages are different, as shown in FIG. 12.

[0085]

[0110] In various implementations, several subwavelength gratings can share the same bias. This allows the output wave to remain within the light cone and creates dephasing between groups or gratings. However, the use of Pockels-based EMLs (such as the VCSEL-EML1200 in FIG. 12) as wavefront modulators may be limited to only certain types of Pockels materials. For example, only Pockels materials with strong r42 can be used.

[0086]

[0111] An exemplary vertical cavity surface emitting laser (VCSEL) based electroabsorption modulated laser (EML) incorporating a high contrast grating (HCG) with contacts on top of a Pockels material according to the present disclosure is shown for use in wavefront modulation. Referring to FIG. 13, a VCSEL-EML 1300 incorporating an HCG structure with a Pockels material is shown.

[0087]

[0112] The VCSEL-EML 1300 may be substantially similar to the VCSEL-EML described with respect to FIG. 9. However, the VCSEL-EML 1300 may differ in that contacts are disposed on the Pockels material as shown in FIG. 13. As shown in FIG. 13, the VCSEL-EML 1300 may function as a wavefront modulator. In this regard, when used as a wavefront modulator, the VCSEL-EML 1300 may operate substantially similarly to the VCSEL-EML 1200 described with respect to FIG. 12. Specifically, the refractive index (RI) may also be altered in the VCSEL-EML 1300 based on varying an electric field applied across the Pockels material, where the electric field is applied from the substrate through the Pockels material to the contacts on top of the Pockels material. As discussed above, altering the RI alters the phase of light passing through the grating, with the contacts being in phase when subjected to the same voltage and out of phase when the voltages are different, as shown in FIG. 13.

[0088]

[0113] 14 illustrates the processing of incident external light in an exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) having a high-contrast grating (HCG) structure incorporating Pockels material according to the present disclosure. Referring to FIG. 14, a VCSEL-EML 1400 is shown incorporating an HCG structure with Pockels material in the gap between the contacts.

[0089]

[0114] The VCSEL-EML 1400 may be substantially similar to the VCSEL-EML 900 described with respect to FIG. 9. However, the high contrast grating (HCG) structure in the VCSEL-EML 1400 may include a different material, such as aluminum gallium arsenide (AlGaAs). Such a design may have various advantages, such as being small, very fast, having low loss, and allowing wavelength tuning by the grating rather than the material (e.g., coarse wavelength division multiplexing (CWDM) or dense wavelength division multiplexing (DWDM) on the same array). The use of an external laser source (e.g., a comb laser) may allow high temperature / low power consumption data transmission.

[0090]

[0115] In Figure 14, the processing of an incident beam (light) projected from the outside (not through the substrate from the bottom) onto the VCSEL-EML 1400 is shown. In this regard, due to dephasing, the absorption resonance of the HCG in the VCSEL-EML 1400 can be tuned, which can cause a change in reflectivity. Thus, when different voltages are applied to the contacts, the contacts are out of phase, which results in the incident light being reflected at a certain angle, as shown in Figure 14.

[0091]

[0116] 15 illustrates the use of an exemplary vertical-cavity surface-emitting laser (VCSEL)-based electroabsorption modulated laser (EML) incorporating a high-contrast grating (HCG) with Pockels material in polarization modulation according to the present disclosure. Referring to FIG. 15, a VCSEL-EML 1500 is shown.

[0092]

[0117] The VCSEL-EML 1500 may be substantially similar to the VCSEL-EML described with respect to FIG. 9. However, the VCSEL-EML 1500 may differ in that a contact (e.g., a metal contact) is disposed on the Pockels material, as shown in FIG. 15. As shown in FIG. 15, the VCSEL-EML 1500 may function as a polarization modulator. Nevertheless, the polarization modulation described herein is not limited to this particular implementation corresponding to the VCSEL-EML 1500, and such polarization modulation may be applicable to and / or provided by any of the proposed EML-based structures disclosed herein.

[0093]

[0118] In this regard, the HCG may have strong birefringence between the transverse electric (TE) and transverse magnetic (TM) modes. Thus, devices can be designed and / or implemented to utilize such properties in providing polarization modulation via the proposed EML-based structures (incorporating Pockels materials). This can be done for any of the implementations disclosed herein. Polarization modulation can be achieved, for example, by utilizing an interdigitated contact arrangement in the proposed EML structures. Thus, the same principles and techniques used in wavefront modulation can be used in polarization modulation, for example, by connecting all the teeth of the HCG to the same bias source. Polarization modulation can be considered as a subset of the amplitude modulation scheme.

[0094]

[0119] For example, polarization modulation can be achieved by applying modulation to enable or inhibit modes within the HCG. In this regard, the HCG characteristics can change specularly near the mode cutoff, as shown in graphs 1510 and 1520, which show an abrupt change in TE reflectivity and an abrupt change in TM reflectivity and an overlap region. In this regard, at the overlapped transition frequency (e.g., of TM6 / TE6), there can be strong sensitivity of both polarizations to refractive index changes. The EML structure can be modified to optimize the polarization modulation. For example, an appropriate thickness of the HCG can make it possible to identify a spot where the TE reflectivity increases as the TM reflectivity decreases (or vice versa) when changing the bias.

[0095]

[0120] FIG. 16 shows an example variation of a high contrast grating (HCG) structure with Pockels material according to the present disclosure. Referring to FIG. 16, various variations of HCG with Pockels material are shown. Specifically, FIG. 16 shows HCG 1600, 1610, 1620, 1630, 1640, and 1650. In this regard, HCG 1600 represents a basic implementation, and HCG 1610, 1620, 1630, 1640, and 1650 represent alternative variations of the basic implementation.

[0096]

[0121] Variations of the basic implementation (HCG1600) may include dimerization variants of HCG. In this regard, such variants may allow for lower resonant frequencies. Such variants may be of different flavors. For example, this can be done by changing geometric parameters such as the width of the high or low refractive index material, as shown in HCG1640 (variant 1), or by changing the material of every other tooth, as shown in HCG1640 (variant 2), or by connecting every other tooth, as shown in HCG1640 (variant 3).

[0097]

[0122] The pattern of HCG can also be varied spatially, for example based on a change in the pattern in the x or y direction. This can include slow shifts of resonance through space, for example, less than 1% variation across lambda as shown in HCG 1640 (variant 4), or abrupt shifts in HCG parameters, for example, as shown in HCG 1640 (variant 5), where one or more parameters have a 1% variation from one iteration of the motif to the next, but the geometry is stable for more than 10 lambda.

[0098]

[0123] A first exemplary implementation of an interdigitated electroabsorption modulated laser (EML)-based structure according to the present disclosure is shown in Figure 17. Referring to Figure 17, an EML-based structure 1700 is shown. Specifically, Figure 17 shows a top view 1710 of the EML-based structure 1700 and a side view 1720 corresponding to a particular cross section (line) in the structure.

[0099]

[0124] As shown in side view 1720, the EML-based structure 1700 includes a generic vertical light-emitting layer followed (in the z-direction) by an insulating layer that is on top of it, and then a high-contrast grating (HCG) that includes two contacts (V1 and V2) that include a semiconductor material (e.g., a doped semiconductor) with a metal on top of it, with a Pockels material disposed between the contacts. The contacts are (optionally) covered by a cap layer (not shown in top view 1710).

[0100]

[0125] The generic vertical light emitting layer may include any suitable structure that can be configured to emit a laser in a vertical direction. In one exemplary implementation, the generic vertical light emitting layer may include a substrate, which may optionally be sandwiched between two vertical light emitting epitaxial stack layers. In this regard, the epitaxial stack may include a VCSEL or a PCSEL (or a second, third, ... nth distributed feedback laser (DFB)). The substrate may include a suitable material, such as gallium arsenide (GaAs), gallium nitride (GaN), indium phosphide (InP), silicon (Si), silicon carbide (SiC), etc.

[0101]

[0126] The insulating layer can be a semiconductor (doped or undoped current blocking layer) or a ceramic (aluminum oxide AlO x , silicon nitride (SiN), silicon oxide (SiO2), etc. Pockels materials can include materials with a large r33.

[0102]

[0127] Materials used for the contacts may include gold (Au), silver (Ag), copper (Cu), or transparent conductive materials (such as indium tin oxide (ITO)).

[0128] The Pockels material used in this implementation may need to have a low refractive index (e.g., IR<2), such as a polymer. As shown in top view 1710, in the example implementation shown in FIG. 17, there may be partial or complete coverage of the doped semiconductor (of the contacts) in the y-direction. The balance between optical losses and RF electrical losses depends on the specific application. As mentioned above, vertical light emitting epistack layers may or may not be included between the substrate and the EML or below the substrate.

[0103]

[0129] A second exemplary implementation of an interdigitated electroabsorption modulated laser (EML)-based structure according to the present disclosure is shown in Figure 18. Referring to Figure 18, an EML-based structure 1800 is shown. Specifically, Figure 18 shows a top view 1810 of the EML-based structure 1800 and a side view 1820 corresponding to a particular cross section (line) in the structure.

[0104]

[0130] As shown in side view 1820, the EML-based structure 1800 includes a generic vertical light-emitting layer followed (in the z-direction) by an insulating layer on top of which is a high-contrast grating (HCG) that includes two contacts (V1 and V2) with a Pockels material disposed between the contacts, which are (optionally) covered by a cap layer (not shown in top view 1810).

[0105]

[0131] The generic vertical light emitting layer may include any suitable structure that can be configured to emit a laser in a vertical direction. In one exemplary implementation, the generic vertical light emitting layer may include a substrate, which may optionally be sandwiched between two vertical light emitting epistack layers. The epistack may include a VCSEL or a PCSEL (or a second, third, ... nth distributed feedback laser (DFB)). The substrate may include a suitable material, such as gallium arsenide (GaAs), gallium nitride (GaN), indium phosphide (InP), silicon (Si), silicon carbide (SiC), etc.

[0106]

[0132] The insulating layer may include a semiconductor (doped or undoped current blocking layer), or a ceramic (aluminum oxide AlOx, silicon nitride (SiN), silicon oxide (SiO2), etc.).

[0107]

[0133] The Pockels material may include a material with a large r33. In the implementation 1800, the contacts (V1 and V2) may include a transparent metal with a low refractive index n<1.6 (e.g., silver nanowires (AgNW), CN, hybrids, etc.).

[0108]

[0134] The Pockels material used in this implementation may need to have a high refractive index >2 (e.g., SBN60, BaTi03, etc.) Also, as with the previous implementation, it may or may not include a vertical light-emitting epitaxial stack layer located between the substrate and the EML or below the substrate.

[0109]

[0135] A third exemplary implementation of an interdigitated electroabsorption modulated laser (EML)-based structure according to the present disclosure is shown in Figure 19. Referring to Figure 19, an EML-based structure 1900 is shown. Specifically, Figure 19 shows a top view 1910 of the EML-based structure 1900 and a side view 1920 corresponding to a particular cross section (line) within the structure.

[0110]

[0136] As shown in side view 1920, the EML-based structure 1900 includes a generic vertical light-emitting layer followed (in the z-direction) by a lateral contact layer that follows or is overlying it, and then a high-contrast grating (HCG) that includes two contacts (V1 and V2) that include a semiconductor (e.g., doped semiconductor) material with a metal over it, with the Pockels material disposed between the contact metal over the Pockels material, and an undoped semiconductor material disposed between the contacts, specifically between the Pockels material as shown. The contacts are (optionally) covered by a cap layer (not shown in top view 1910).

[0111]

[0137] The generic vertical light emitting layer may include any suitable structure that can be configured to emit a laser in a vertical direction. In one exemplary implementation, the generic vertical light emitting layer may include a substrate, which may optionally be sandwiched between two vertical light emitting epistack layers. The epistack may include a VCSEL or a PCSEL (or a second, third, ... nth distributed feedback laser (DFB)). The substrate may include a suitable material, such as gallium arsenide (GaAs), gallium nitride (GaN), indium phosphide (InP), silicon (Si), silicon carbide (SiC), etc.

[0112]

[0138] The lateral contact layer may include a transparent conductive material, such as a Pockels material with large r42, 63, etc. The contact material may include gold (Au), silver (Ag), copper (Cu), or a transparent conductive material, such as indium tin oxide (ITO).

[0113]

[0139] The Pockels material used in this implementation may need to have a low refractive index (e.g., IR<2), such as KDP, polymer, etc. In some cases, the lateral contact layers may be biased in this implementation, resulting in three different biases. Nevertheless, in many cases, the bias applied to the lateral contact layers may be the same as the bias applied to one of the contacts (e.g., V3=V2=0). Also, as with the previous implementation, a vertical light emitting epistack layer may or may not be included between the substrate and the EML or below the substrate.

[0114]

[0140] 20 illustrates fourth and fifth exemplary implementations of interdigitated electroabsorption modulated laser (EML)-based structures according to the present disclosure. Referring to FIG. 20, EML-based structures 2000 and 2010 (each shown in a side view) are illustrated.

[0115]

[0141] As shown in Figure 20, each of the EML-based structures 2000 and 2010 includes a generic vertical light-emitting layer followed (in the z-direction) by a lateral contact layer that is on top of it, and then a high-contrast grating (HCG) that includes two contacts (V1 and V2) that include a semiconductor (e.g., doped semiconductor) material with a metal on top of it, with the contact metal on top of the Pockels material, and with undoped semiconductor material disposed between the contacts, specifically between the Pockels materials, as shown. The contacts are (optionally) covered by a cap layer (not shown in the top view 2010).

[0116]

[0142] The generic vertical light emitting layer may include any suitable structure that can be configured to emit a laser in a vertical direction. In one exemplary implementation, the generic vertical light emitting layer may include a substrate, which may include a light emitting epitaxial stack layer on either side of the substrate. The epitaxial stack may include a VCSEL or a PCSEL (or a second, third, ... nth distributed feedback laser (DFB)). The substrate may include a suitable material, such as gallium arsenide (GaAs), gallium nitride (GaN), indium phosphide (InP), silicon (Si), silicon carbide (SiC), etc.

[0117]

[0143] The lateral contact layer may include a transparent conductive material, such as a Pockels material with large r42, 63, etc. The contact material may include gold (Au), silver (Ag), copper (Cu), or a transparent conductive material, such as indium tin oxide (ITO).

[0118]

[0144] EML-based structures 2000 and 2010 may be substantially similar to EML-based structure 1900 described with respect to Figure 19. However, EML-based structures 2000 and 2010 differ from each other (and from EML-based structure 1900) in that there are some variations in the HCG in each of these structures. Specifically, the HCG of EML-based structure 2000 differs from the HCG of EML-based structure 2000 in that in EML-based structure 2000, the contacts (V1 and V2) are of different sizes (e.g., V1 is larger than V2 as shown in Figure 20), whereas in EML-based structure 1900, these contacts are of the same size.

[0119]

[0145] The EML-based structure 2010 differs in that the HCG used incorporates a cap layer material (in addition to the undoped semiconductor material) between the contacts as shown in FIG. 20. The EML-based structures 2000 and 2010 also differ from the EML-based structure 1900 in that the biases are different (e.g., V1=V2≠V3). However, these two implementations may exhibit similar physical effects as the interdigitated EML-based implementations, since the effective refractive index varies in different ways in each dimer. In this regard, a similar effect can be obtained by filling, for example, only about half of the HCG lobe with Pockels material, as shown in FIG. 20.

[0120]

[0146] FIG. 21 illustrates a sixth exemplary implementation of an interdigitated electroabsorption modulated laser (EML) based structure according to the present disclosure.

[0147] Referring to Figure 21, there is shown an EML-based structure 2100. Specifically, Figure 21 shows a top view 2110 of the EML-based structure 2100 and a side view 2120 corresponding to a particular cross section (line) of the structure.

[0121]

[0148] As shown in side view 2120, EML-based structure 2100 includes a generic vertical emitter layer followed (in the z-direction) by a lateral contact layer that is on top of it, and then a high contrast grating (HCG) that includes two contacts (V1 and V2) that include a semiconductor (e.g., doped semiconductor) material, with metal on top of the Pockels material. The contacts are (optionally) covered by a capping layer (not shown in top view 2110). As shown, the capping material is also disposed between the contacts, specifically between the Pockels materials.

[0122]

[0149] The generic vertical light emitting layer may include any suitable structure that can be configured to emit a laser in a vertical direction. In one exemplary implementation, the generic vertical light emitting layer may include a substrate, which may include light emitting epi-stack layers on either side. The epi-stack may include a VCSEL or a PCSEL (or a second, third, ... nth distributed feedback laser (DFB)). The substrate may include a suitable material, such as gallium arsenide (GaAs), gallium nitride (GaN), indium phosphide (InP), silicon (Si), silicon carbide (SiC), etc.

[0123]

[0150] The lateral contact layer may include a transparent conductive material, such as a Pockels material with large r42, 63, etc. The contact material may include gold (Au), silver (Ag), copper (Cu), or a transparent conductive material, such as indium tin oxide (ITO).

[0124]

[0151] Similar to EML-based structure 1900, the Pockels material used in this implementation may need to have a low refractive index (e.g., IR<2), such as KDP, polymer, etc., and in some cases, the lateral contact layers may be biased, resulting in three different biases (although in many cases the bias applied to the lateral contact layers may be the same as the bias applied to one of the contacts (e.g., V3=V2=0). Also, similar to the previous implementation, a vertical light emitting epistack layer may or may not be included between the substrate and the EML or below the substrate. Although not shown, similar to EML-based structure 1900, alternative implementations may be used by modifying the HCG structure in a manner similar to how the HCG is modified in EML-based structures 2000 and 2010 compared to EML-based structure 1900, as described with respect to FIG. 20.

[0125]

[0152] An exemplary vertical cavity surface emitting laser (VCSEL) based electroabsorption modulated laser (EML) incorporating a high contrast grating (HCG) with a Pockels material and with a gate dielectric according to the present disclosure is shown in Figure 22. Referring to Figure 22, a VCSEL 2200 is shown.

[0126]

[0153] The VCSEL2200 may include a VCSEL epilayer (with no or only a few top pairs) having a lattice (e.g., HCG) structure thereon with a Pockels material filling the gaps in the lattice structure, and with contacts on the surface of the lattice structure. Some of the contacts may incorporate a dielectric (for the gate). Thus, some of the contacts (e.g., contacts without a dielectric) may form and / or function as a ground, and the remaining contacts (e.g., contacts incorporating a dielectric) may function as RF elements in the VCSEL2200.

[0127]

[0154] Exemplary vertical-cavity surface-emitting laser (VCSEL)-based optical devices, one of which incorporates an electroabsorption-modulated laser (EML)-based design, are shown in Figure 23. Shown in Figure 23 are optical devices 2300 and 2310, both of which are VCSEL-based devices. In this regard, top views of optical devices 2300 and 2310 are shown in Figure 23.

[0128]

[0155] As shown in Figure 23, optical device 2300 includes a VCSEL-based structure (e.g., as described in connection with Figure 2) on a substrate etch with contacts (wiring) on ​​the VCSEL structure. Optical device 2300 receives RF as an input to the contact wiring at one end. in Applying a signal and outputting the corresponding RF at the other end of the contact wire out / dump In response to the output of the signal, it can be configured to emit light (eg, a laser).

[0129]

[0156] Optical device 2310 represents an example modification of optical device 2300 according to an example implementation based on the present disclosure. In this regard, optical device 2310 may be substantially similar to optical device 2300, but may incorporate modifications to enable it to provide the modulation functionality and / or characteristics described herein. For example, optical device 2310 may incorporate modifications of contact wiring, such as by using multiple separate contact wirings as shown in FIG. 23 to form an interdigitated lattice-based design that enables biasing of the contacts, as described above, such as by grounding (e.g., applying a ground signal) some of the contact wirings as shown in FIG.

[0130]

[0157] As used herein, "and / or" means any one or more of the items in the list connected by "and / or." As an example, "x and / or y" means any element of the 3-tuple {(x), (y), (x, y)}. In other words, "x and / or y" means "one or both of x and y." As another example, "x, y and / or z" means any element of the 7-tuple {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words, "x, y and / or z" means "one or more of x, y and z." As used herein, the term "exemplary" means serving as a non-limiting example, instance or illustration. As used herein, the terms "for example" and "eg" introduce a description of one or more non-limiting examples, instances or illustrations.

[0131]

[0158] As used herein, the terms "circuit" and "circuitry" refer to physical electronic components (e.g., hardware) and any software and / or firmware ("code") that may comprise, be executable by, and / or otherwise be associated with hardware. As used herein, for example, a particular processor and memory (e.g., volatile or non-volatile memory devices, general-purpose computer-readable media, etc.) may comprise a first "circuit" when executing a first one or more lines of code and a second "circuit" when executing a second one or more lines of code. Furthermore, a circuit may include analog and / or digital circuits. Such circuitry may operate, for example, on analog and / or digital signals. It should be understood that a circuit may be in a single device or chip, on a single motherboard, in a single chassis, in multiple enclosures in a single geographic location, in multiple enclosures distributed across multiple geographic locations, etc. Similarly, the term "module" may refer to, for example, physical electronic components (e.g., hardware) as well as any software and / or firmware ("code") that may comprise, be executable by, and / or be otherwise associated with the hardware.

[0132]

[0159] As used herein, circuitry or a module is "operable" to perform a function when it contains the necessary hardware and code (if any) to perform the function, regardless of whether performance of the function has been disabled or enabled (e.g., by a user-configurable setting, factory default, etc.).

[0133]

[0160] Other embodiments of the present invention may provide a non-transitory computer readable medium and / or storage medium having machine code and / or a computer program stored thereon, the machine code and / or computer program having at least one code segment executable by a machine and / or computer, thereby causing the machine and / or computer to perform the processes described herein.

[0134]

[0161] Various embodiments according to the invention may also be embodied in a computer program product, which includes all features enabling the implementation of the methods described herein and which is capable of carrying out these methods when loaded into a computer system. A computer program in this context means any expression, in any language, code or notation, of a set of instructions intended to cause a system having information processing capabilities to perform a particular function, either directly, or after a) conversion into another language, code or notation, or b) reproduction in a different concrete form, or both.

[0135]

[0162] Although the presented methods and / or systems have been described with reference to certain implementations, those skilled in the art will recognize that various modifications can be made and equivalents substituted without departing from the scope of the presented methods and / or systems. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the scope of the present disclosure. Thus, the presented methods and / or systems are not limited to the particular implementations disclosed, but rather it is intended that the presented methods and / or systems include all implementations falling within the scope of the appended claims.

Claims

1. A light source; an electroabsorption modulated laser (EML)-based structure on said light source; An optical device comprising: the EML-based structure includes a lattice structure; the lattice structure includes a plurality of lattice lines; the lattice structure further comprises a Pockels material disposed within the lattice structure. Optical devices.

2. 10. The optical device of claim 1, wherein at least a portion of the Pockels material is disposed within the plurality of grating lines.

3. 10. The optical device of claim 1, wherein at least a portion of the Pockels material is disposed in gaps between the plurality of grid lines.

4. 10. The optical device of claim 1, wherein at least one grid line of the plurality of grid lines includes a base comprising a Pockels material having a contact on the base.

5. 10. The optical device of claim 1 further comprising a substrate carrying both the electroabsorption modulated laser (EML)-based structure and the light source.

6. The optical device of claim 1 , wherein the grating structure comprises a high contrast grating (HCG) based structure.

7. 10. The optical device of claim 1, wherein the light source comprises a vertical cavity surface emitting laser (VCSEL) based structure.

8. 8. The optical device of claim 7, wherein the vertical cavity surface emitting laser (VCSEL) based structure includes at least a top mirror layer, a bottom mirror layer, and a quantum well layer disposed between the top mirror layer and the bottom mirror layer.

9. The optical device of claim 1 , wherein the light source comprises a photonic crystal surface emitting laser (PCSEL) based structure.

10. The optical device of claim 1 , wherein the light source comprises a high-order distributed feedback polymer (DFB) based structure.

11. 10. The optical device of claim 1, wherein the electroabsorption modulated laser (EML)-based structure is configured to impart amplitude modulation to an incident beam or wave applied to the EML-based structure.

12. 12. The optical device of claim 11 , wherein the grating structure includes one or more grating features or characteristics configured to adjust or modify an intensity or power of an output beam or wave corresponding to the input beam or wave when imparting the amplitude modulation.

13. 10. The optical device of claim 1, wherein the electroabsorption modulated laser (EML)-based structure is configured to impart wavefront modulation to an incident beam or wave applied to the EML-based structure.

14. 14. The optical device of claim 13, wherein the electroabsorption modulated laser (EML) based structure is configured to provide the wavefront modulation based on tuning of a refractive index (RI) associated with the electroabsorption modulated laser (EML) based structure.

15. 15. The optical device of claim 14, wherein the electroabsorption modulated laser (EML) based structure is configured to allow tuning of the refractive index (RI) based on biasing or alteration of an electric field applied across the Pockels material.

16. 14. The optical device of claim 13, wherein the grating structure is configured to deflect the incident beam or wave to one or more discrete angles when imparting the wavefront modulation.

17. 10. The optical device of claim 1, wherein the electroabsorption modulated laser (EML)-based structure is configured to impart polarization modulation to an incident beam or wave applied to the EML-based structure.

18. 20. The optical device of claim 17, wherein the grating structure, when imparting the polarization modulation, is configured to impart a polarization rotation to an output beam or wave corresponding to the input beam or wave.

19. 20. The optical device of claim 17, wherein the grating structure includes one or more grating features configured for use in providing the polarization modulation, the one or more grating features being essentially linear polarizers.

20. 20. The optical device of claim 19, wherein the one or more grating features are configured to selectively transmit a light beam having a polarization in a particular direction.

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