Heterogeneous photonics platform

Abstract

A heterogeneous photonics platform for photonic integrated chips is described. The platform can comprise waveguides formed on two microfabrication levels. There can be optical coupling between waveguides on the two levels. At least one optical waveguide on one or both of the microfabrication levels is doped with a rare-earth ion or transition metal ion to provide optical gain when optically pumped. An optically active material, such as an electro-optic material, a nonlinear optic material, or a color-center-containing material can be optically coupled to one or more waveguides on the first or second microfabrication levels. Semiconductor material can also be integrated in the platform for a semiconductor device.

Description

Attorney Docket No. BCNP-004W001Heterogeneous Photonics PlatformCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims a priority benefit under 35 U.S.C. § 119(e) to U.S. provisional application Ser. No. 63 / 774,939 titled, “Heterogeneous Photonics Platform,” filed March 20, 2025, which application is incorporated herein by reference in its entirety.BACKGROUND

[0002] Heterogeneous integration of microelectronic chips has become widespread in the industry to increase chip functionality. Similarly, the functionality of photonic chips can be increased with heterogeneous integration of microscale optical devices made from different materials.SUMMARY

[0003] The present disclosure relates to heterogeneous integration of microscale optical devices that include different types of optically active waveguides (e.g., waveguides providing optical gain for optical amplification, waveguides providing optical modulation of phase, frequency, and / or amplitude, waveguides containing color centers, and waveguides providing wavelength conversion by a nonlinear optical process), passive waveguides, and in some cases semiconductor devices. A first type of active waveguide can be waveguides doped with rare-earth ions or transition metal ions to provide optical gain when optically pumped. A second type of active waveguide can be waveguides comprising or coupled to optically active materials for interacting with optical waves traveling in the waveguide. In some cases, the optically active material comprises color-center-containing material. The passive waveguides can be low-loss waveguides to route signals and / or to couple signals between different waveguides formed in different microfabrication levels on a heterogeneous photonic integrated chip.

[0004] Some implementations relate to heterogeneous integrated optical systems comprising: a substrate; a first microfabrication level comprising a first optical waveguide disposed on the substrate; a second microfabrication level comprising a second optical waveguide disposed on the substrate, wherein the first microfabrication level is located between the substrate and the second microfabrication level; and an optically active material located to optically couple to the first optical waveguide or the second optical waveguide, wherein the optically activeAttorney Docket No. BCNP-004W001material is an electro-optic material or a nonlinear optical material or a color-center-containing material and at least a portion of the first optical waveguide or at least a portion of the second optical waveguide is doped with a rare-earth ion or a transition metal ion to provide optical gain when the portion of the first optical waveguide or the portion of the second optical waveguide is optically pumped

[0005] Some implementations relate to methods of fabricating a heterogeneous integrated optical system. Such methods can include acts of: forming, on a substrate, a first microfabrication level comprising a first optical waveguide; forming, on the substrate, a second microfabrication level comprising a second optical waveguide; disposing optically active material on the substrate, wherein the optically active material is located to optically couple to the first optical waveguide or the second optical waveguide; and doping at least a portion of the first optical waveguide or doping at least a portion of the second optical waveguide with a rare-earth ion or a transition metal ion to provide optical gain when the portion of the first optical waveguide or the portion of the second optical waveguide is optically pumped.

[0006] All combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are part of the inventive subject matter disclosed herein. In particular, all combinations of subject matter appearing in this disclosure are part of the inventive subject matter disclosed herein. The terminology used herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The skilled artisan will understand that the drawings primarily are for illustrative purposes and are not intended to limit the scope of the inventive subject matter described herein. The drawings are not necessarily to scale; in some instances, various aspects of the inventive subject matter disclosed herein may be shown exaggerated or enlarged in the drawings to facilitate an understanding of different features. In the drawings, like reference characters generally refer to like features (e.g., functionally and / or structurally similar elements).Attorney Docket No. BCNP-004W001

[0008] FIG. 1 depicts a cross-sectional view of a heterogeneous photonics platform which comprises waveguides formed in two microfabrication levels, a region of doped waveguide, and a region of electro-optic material all integrated on a silicon substrate.

[0009] FIG.2 depicts cross-sectional views of structure relating to a fabrication process for making doped and undoped waveguides in the same layer by patterned ion implantation before waveguide etching.

[0010] FIG.3 depicts cross-sectional views of structure relating to a fabrication process for making doped and undoped waveguides in the same layer by patterned ion implantation before waveguide etching. In this fabrication process, the layer deposition and patterned ion implantation steps are repeated to improve doping uniformity through the doped waveguide region.

[0011] FIG. 4 depicts cross-sectional views of structure relating to a fabrication process for making doped and undoped waveguides in different microfabrication levels using ion implantation.

[0012] FIG. 5A depicts cross-sectional views of structure relating to a fabrication process for making undoped and doped waveguides in different microfabrication levels using doped sputtered films.

[0013] FIG. 5B depicts cross-sectional views of structure relating to a fabrication process for making undoped and doped waveguides in direct physical contact with each other.

[0014] FIG. 6A plots simulated doping profiles through a vertical cut in a waveguide. Two different species can be used to co-dope the same film with a high overlap factor by adjusting the ion implantation energy by the ratio of the atomic masses.

[0015] FIG. 6B shows a cross-sectional scanning electron microscope image of a dielectric waveguide with an overlay showing the region of the waveguide with rare earth dopants.

[0016] FIG. 6C plots a simulated optical mode profile for a dielectric waveguide with outer dimensions marked by the solid white lines. The dashed white lines show the full-width halfmaximum border for implanted rare earth dopants for the simulation parameters from FIG.6A

[0017] FIG. 6D plots simulated optical gain as a function of dopant ion concentration. The waveguide achieves net gain when the optical gain exceeds the background loss.Attorney Docket No. BCNP-004W001

[0018] FIG. 7A depicts a fabrication process for chip-on-wafer integration of an electro-optic material onto a photonics wafer platform.

[0019] FIG. 7B depicts cross-sectional views of structure relating to a fabrication process for chip-on-wafer integration of an electro-optic material into the heterogeneous photonics platform, as depicted in FIG. 1.

[0020] FIG. 8A depicts a fabrication process for wafer-on-wafer integration of an electrooptic material onto a photonics wafer platform.

[0021] FIG. 8B depicts cross-sectional views of structure relating to a fabrication process for wafer-on-wafer integration of an electro-optic material into the heterogeneous photonics platform, as depicted in FIG. 1. As indicated in the last panel, full and / or partial etches can be used to pattern rib or strip waveguides in the electro-optic material.

[0022] FIG. 9A plots simulated optical mode profiles for light in the upper waveguide layer in regions without (left panel) and with (right panel) the electro-optic material.

[0023] FIG. 9B depicts a cross-sectional view along the propagation axis of a transition from a region of the photonic circuit without an electro-optic material to a region with the electrooptic material.

[0024] FIG. 9C depicts transverse cross-sectional views of each labeled region in FIG. 9B.

[0025] FIG. 9D plots the result of an optical propagation simulation through the photonic circuit in FIG. 9B and FIG. 9C. The two waveguide layers facilitate low-loss transitions across the electro-optic material boundary.

[0026] FIG. 10A depicts a perspective view of the transition across the electro-optic material boundary using two waveguide layers with key design parameters labeled.

[0027] FIG. 10B plots simulated optical transmission efficiency as a function of waveguide height and width.

[0028] FIG. 10C plots simulated optical transmission efficiency as a function of the taper length.

[0029] FIG. 11A depicts transitioning between a lower dielectric waveguide and a partially etched, rib waveguide in the integrated electro-optic thin film. Cross-sectional views of the platform structure are also depicted for the three marked locations along the transition.Attorney Docket No. BCNP-004W001

[0030] FIG. 11B depicts transitioning between a lower dielectric waveguide and a fully etched, strip waveguide in the integrated electro-optic thin film. Cross-sectional views of the platform structure are also depicted for the two marked locations along the transition.

[0031] FIG. 12A depicts regions of optical transparency for candidate waveguide, cladding, and electro-optic materials in the heterogeneous photonics platform.

[0032] FIG. 12B depicts a cross-sectional view of an upper silicon-nitride waveguide with an integrated thin film of lithium niobate.

[0033] FIG. 12C plots simulated optical mode profiles for the geometry of FIG. 11B at three different infrared wavelengths.

[0034] FIG. 13 depicts a variation on the cross-sectional view from FIG. 1 in which metal is also integrated directly above a waveguide to act as a heater for thermo-optic tuning.

[0035] FIG. 14 depicts an example application of the heterogeneous photonics platform illustrated in FIG 1. In this implementation, a rare-earth seed laser is split and amplified into an array of waveguide channels. Each channel is independently modulated in an electro-optical modulator array before being transmitted to other photonic elements.

[0036] FIG. 15 depicts a variation on the cross-sectional view from FIG. 1 in which III-V material is also integrated directly above a waveguide to act as a photodetector or laser source.

[0037] FIG. 16 depicts an example application of the heterogenous photonics platform illustrated in FIG. 15. In this embodiment, the output from a rare-earth seed laser is modulated and processed before being detected with integrated III-V photodetectors.

[0038] FIG. 17 depicts a variation on the cross-sectional view from FIG. 1 in which III-V material is also integrated to be butt-coupled to a waveguide and function as a photodetector or laser source.

[0039] FIG. 18 depicts an example application of the heterogenous photonics platform illustrated in FIG. 17. In this implementation, the output from an integrated III-V laser is amplified with a rare-earth doped waveguide, modulated, and then processed before being detected with integrated III-V photodetectors.Attorney Docket No. BCNP-004W001DETAILED DESCRIPTION

[0040] FIG. 1 depicts a cross-sectional view of structure that can be in a heterogeneous photonics platform 100. The heterogeneous photonics platform 100 comprises optical waveguides 111, 113, 115, 117 formed in two microfabrication levels 120, 130. At least a portion of at least one of the optical waveguides (waveguide 113 in the illustrated example) can comprise a doped region 125. The doped region 125 can be doped with a rare-earth ion (e.g., erbium, ytterbium, thulium, neodymium, or praseodymium ions) or a transition metal ion (e.g., nickel, chromium, or titanium ions) to provide optical gain when the doped region 125 is optically pumped. The doped region 125 can comprise a single atomic species of an ionized element or two or more atomic species for co-doping. In some implementations, the doped region can include one or more optically inactive dopants to increase incorporation of the rare-earth ion or the transition metal ion. The heterogeneous photonics platform 100 can further comprise optically active material 145 (e.g., electro-optic material such as lithium niobate, lithium tantalate, or barium titanate used for electro-optic functionality, nonlinear optical material such a beta barium borate (BBO) or periodically poled lithium niobate (PPLN) used for nonlinear optical functionality, and / or color-center-containing material used for quantum optical applications, lasers, or for integrated photonics applications) coupled to one of the optical waveguides in the first microfabrication level 120 or the second microfabrication level 130 (coupled to waveguide 117 in the second microfabrication level 130 in the illustrated example). An electro-optic material is a material that upon application of an electric field, can modify the phase of an optical wave traveling through the electro-optic material. Such electro-optic materials may exhibit the Pockels effect or Kerr effect. The optically active material 145 can be part of an optical device 150 formed in a third microfabrication level 140. In some cases, the optical device 150 can be configured to modulate the amplitude and / or phase of an optical wave traveling in the coupled waveguide 117 or to convert the wavelength of an optical wave traveling in the coupled waveguide 117 by a nonlinear optical process. In some cases, the optically active material 145 (e.g., color-center-containing material) can be used for sensing or information storage. Examples of color-center-containing materials include, but are not limited to, alkali halides (NaCl, KC1), metal oxides (ZnO), semiconductors such as silicon and silicon nitride, and other crystals such as diamond (potentially with nitrogen vacancies) and quartz. Color centers in these materials can be formed by a crystal lattice defect, such as a missing ion in the lattice.Attorney Docket No. BCNP-004W001

[0041] In the context of a heterogeneous photonics platform 100, a “microfabrication level” is a portion of the platform extending parallel to a planar surface 106 of the substrate 105 and having a thickness t. The microfabrication level can comprise at least one optical waveguide, at least one optical device, at least one electro-optical device, at least one nonlinear optical device, and / or at least one electronic device extending parallel to the planar surface 106 of the substrate. A “microfabrication level” as used herein can comprise several different materials, at least some of which may be deposited in layers or bonded to the substrate and subsequently patterned and etched or processed in other ways (e.g., implanted with ions). In a stack of devices, a microfabrication level comprises one or more layers used to form one or more devices with the same layer(s) in the stack of devices. The thickness t of a microfabrication level can be from approximately or exactly 100 nm to approximately or exactly 5 microns. Buried microfabrication levels can be planarized after deposition of a cladding layer or passivation layer to form a planar surface for fabricating the next microfabrication level in a stack of microfabrication levels.

[0042] The optical device 150 and waveguides 111, 113, 115, 117 (which can include passive waveguides for routing purposes and active waveguides to provide optical gain) can be integrated on a same substrate 105 to form the heterogeneous photonics platform 100. The substrate 105 can be, for example, a silicon substrate though other types of substrates can be used. Other substrates can be formed from other semiconductor materials (e.g., indium phosphide, gallium arsenide, gallium nitride, efc.), ceramics, or glasses.

[0043] In some cases, an oxide layer 107 can be disposed between the substrate 105 and the first microfabrication level 120. The oxide layer 107 can be thermal oxide grown on the substrate 105 and can provide optical cladding functionality for waveguides 111, 113 formed in the first microfabrication level 120. A first dielectric material 121 (such as an oxide) can be deposited as part of a process to form the first microfabrication level 120. The first dielectric material 121 can provide optical cladding functionality for optical waveguides 111, 113 in at least the first microfabrication level 120 and may further provide optical cladding functionality for optical waveguides 115, 117 in the second microfabrication level 130. A second dielectric material 131 (such as an oxide) can be deposited as part of a process to form the second microfabrication level 130. The second dielectric material 131 can provide optical cladding functionality for optical waveguides 115, 117 in at least the second microfabrication level 130 and may further provide optical cladding functionality for an optical waveguide formed from the optically active material 145.Attorney Docket No. BCNP-004W001

[0044] FIG. 2 depicts cross-sectional views of structures relating to a fabrication process for making doped and undoped waveguides in the same microfabrication level 120. The process depicts patterned ion implantation in which a first resist mask 210 (ion implantation mask) is lithographically patterned to create an opening through which ions can be implanted into optical waveguide material. One, two, or more different ionized rare-earth elements or one, two, or more different ionized transition metal elements can be implanted into the optical waveguide material. A second resist mask 212 (waveguide mask) can be lithographically patterned to define optical waveguides in the waveguide material for anisotropic etching (e.g., by reactive ion etching). After stripping the second resist mask, dielectric material 121 can be deposited and planarized as cladding material for the optical waveguides. In this and other fabrication processes described herein, some fabrication steps (e.g., deposition, patterning, and removing photoresist, chemical mechanical polishing of deposited layers) are omitted for simplicity.

[0045] FIG. 3 depicts cross-sectional views of structures relating to a fabrication process for making doped and undoped waveguides in the same microfabrication level 120 by patterned ion implantation followed by waveguide etching. In this fabrication process, the optical waveguide material for the waveguides 111, 113 is deposited and subjected to patterned ion implantation in repeated steps to build up the waveguides layer by layer. Material deposited and used to form the waveguides 111, 113 can comprise a nitride (e.g., aluminum nitride and silicon nitride), an oxide (e.g., aluminum oxide and tantalum oxide), and / or other materials such as amorphous silicon. The repeated steps of waveguide material deposition and patterned ion implantation can improve doping uniformity through the doped waveguide region. The waveguides can be etched in a single step after the full thickness of the waveguide has been reached.

[0046] FIG. 4 depicts cross-sectional views of structure relating to a fabrication process for making doped and undoped waveguides in different microfabrication levels. In this process, doping of the lower level waveguide 113 is done by a blanket ion implantation process. The process of FIG. 2 or FIG. 3 can be used to form doped or undoped waveguides in the second microfabrication level 130.

[0047] FIG. 5A depicts cross-sectional views of structures relating to a fabrication process for making doped and undoped waveguides in different microfabrication levels. In this process a doped film 510 is deposited as optical waveguide material for one of theAttorney Docket No. BCNP-004W001microfabrication levels and subsequently etched, using a patterned etch-resistant mask 505, to form a doped optical waveguide 515. The doping of the deposited film can comprise doping with one, two, or more different ionized rare-earth elements or one, two, or more different ionized transition metal elements (e.g., to form a co-doped optical waveguide 515). The doped film may be deposited by a physical vapor deposition method (e.g., sputtering, electron beam deposition, thermal deposition, or pulsed laser deposition). This process avoids patterned ion deposition before etching the waveguide and can be used instead of the processes described in FIG. 2 and FIG. 3 to form a doped waveguide. In some implementations, the doped film may be deposited using a bonding process (e.g., bonding the layer to the substrate from another handle wafer and etching away the substrate of the handle wafer).

[0048] FIG. 5B depicts cross-sectional views of structures relating to a fabrication process for making doped and undoped waveguides in direct physical contact. The process is similar to that shown in FIG. 5A except that a silicon dioxide layer is not deposited over the undoped waveguides 508. Instead, the doped film 510 is deposited directly on the undoped waveguides 508. The doped film 510 can subsequently be patterned and etched, using a patterned etch-resistant mask 506, to form a doped waveguide 515. The doping of the deposited film can comprise doping with one, two, or more different ionized rare-earth elements or one, two, or more different ionized transition metal elements (e.g., to form a codoped optical waveguide 515). The doped film 510 may be deposited by a physical vapor deposition method (e.g., sputtering, electron beam deposition, thermal deposition, or pulsed laser deposition). This process avoids patterned ion deposition before etching the waveguide and can be used instead of the processes shown in FIG. 2 and FIG. 3 to form a doped waveguide 515 in direct physical contact with an undoped waveguide 508. Direct physical contact can be used to increase optical coupling between the undoped waveguide 508 and the doped waveguide 515. A portion of the doped film 515 can be retained adjacent to the undoped waveguide 508 to provide lateral cladding material for the undoped waveguide 508. As such, material used to form the doped waveguide 515 is disposed adjacent to three sides of the undoped waveguide 508 in a portion of the two waveguides where they optically couple to each other.

[0049] FIG. 6A plots simulated doping profiles through a vertical cut in a co-doped optical waveguide. Two different rare-earth atomic species (e.g., erbium and ytterbium) can be usedAttorney Docket No. BCNP-004W001to co-dope the same film with a high overlap factor by adjusting the ion implantation energy by the ratio of the atomic masses.

[0050] FIG. 6B shows a cross-sectional scanning electron microscope image of an optical waveguide formed from dielectric material. A dashed line rectangular overlay indicates the region of the waveguide into which rare-earth dopants have been implanted.

[0051] FIG. 6C plots a simulated optical mode profile for an optical waveguide having a waveguide core formed from a first dielectric material (silicon nitride) and clad with a surrounding second dielectric material (silicon dioxide). The outer dimensions of the waveguide core are indicated with solid white lines in the plot. The dashed white lines indicate the full-width half-maximum (FWHM) border for implanted rare-earth dopants based on the simulation results plotted in FIG. 6A.

[0052] FIG. 6D plots simulated optical gain as a function of peak dopant ion concentration in the waveguide core. The waveguide achieves net gain when the optical gain exceeds the background loss.

[0053] FIG. 7A depicts a fabrication process for integrating an optically active material 145 (e.g., an electro-optic material, nonlinear optical material, or color-center-containing material) onto a photonics wafer 710 to make a heterogeneous photonics platform 100. The optically active material can be formed on a separate handle wafer 720 (an electro-optic wafer in this example) and cut into dies 725. The dies can be flipped and bonded to the photonics wafer 710 which can have optical waveguides formed in one or more microfabrication levels. After bonding, the substrate from the handle wafer 720 can be etched away leaving the optically active material 145 bonded and integrated on the photonics wafer.

[0054] FIG. 7B depicts cross-sectional views of structures relating to a fabrication process for integrating optically active material 145 onto the heterogeneous photonics platform 100 of FIG. 1. The optically active material 145 can optically couple to a waveguide of the heterogeneous photonics platform 100. The optically active material 145 can be used to form an electro-optic device (e.g., a phase and / or amplitude modulator), a nonlinear optical device (e.g, a frequency doubler, optical parametric oscillator, or optical parametric amplifier), and / or a color-center device (e.g, an optical sensor, a quantum optical device) on the photonics platform 100.Attorney Docket No. BCNP-004W001

[0055] FIG. 8A depicts a fabrication process for integrating an optically active material 145 onto a photonics wafer 710 to make a heterogeneous photonics platform 100. In this approach, the handle wafer 720 carrying the optically active material 145 is bonded to the photonics wafer 710. After wafer-to-wafer bonding and substrate removal, patterning and etching of the optically active material 145 can be done to define electro-optic devices, nonlinear optical devices, and / or color-center devices. Subsequent deposition and patterning of a metal layer can be done to define electrodes or heater elements.

[0056] FIG. 8B depicts cross-sectional views of structures relating to a fabrication process for wafer-to-wafer bonding to integrate optically active material onto the heterogeneous photonics platform 100 of FIG. 1. As indicated in the last panel of the series of panels in FIG. 8B, full and / or partial etches through the optically active material 145 can be performed to pattern strip or rib waveguides, respectively, in the optically active material. A partial etch is shown in the example. A resist mask (not illustrated) can be used to define the pattern for the waveguide(s) etched in the optically active material 145.

[0057] FIG. 9A plots simulated optical mode profiles for light in an optical waveguide 913 (indicated by the rectangle) that is formed in a first microfabrication level 120. For the plot of the left panel, there is no optically active material disposed over a first region of the optical waveguide 913. For the plot of the right panel, an optically active material 145 is disposed over and optically coupled to the optical waveguide 913.

[0058] FIG. 9B depicts a cross-sectional view of structure that can be included in a photonic circuit on a heterogeneous photonics platform 100. The illustrated view is along the propagation axis of a first optical waveguide 911 and second optical waveguide 913 through six distinct regions of the photonic circuit. The first optical waveguide transitions from a first region 920 of the photonic circuit with no optically active material to a second region 930 where a second optical waveguide 913 couples to the first optical waveguide 911 and where the optically active material 145 couples to the second waveguide 913. In the illustrated example, the optically active material 145 directly contacts the second waveguide 913.

[0059] FIG. 9C depicts cross-sectional views of the structure depicted in FIG. 9B. The cross-sectional views are taken at the locations marked with Roman numerals i-vi and are in a direction transverse to the optical waveguide 911 (also transverse to the direction of optical mode propagation along the waveguide 911). The first optical waveguide 911 and the second optical waveguide 913 are adiabatically tapered near their ends, forming a transition regionAttorney Docket No. BCNP-004W001for optical coupling from the first optical waveguide 911 to the second optical waveguide 913 or vice versa.

[0060] FIG. 9D plots the result of an optical propagation simulation through the photonic circuit in FIG. 9B and FIG. 9C. The region of optical coupling between the two optical waveguides 911, 913 can be used in either direction and can provide low-loss transfer of optical power to and from the optically active material 145.

[0061] FIG. 10A depicts a perspective view of the tapered waveguide structure of FIGS. 9B - 9C where optical power transfers to the optically active material 145 from the first optical waveguide 911. Design parameters waveguide width, height, taper length, and gap are labeled in the drawing. The design parameters are selected to improve coupling efficiency between the waveguides and reduce coupling losses.

[0062] FIG. 10B plots simulated modal mismatch loss at the discontinuity when a waveguide 911 is incident to an optically active material 145 with a gap of 600 nm as a function of waveguide height and width. FIG. 10C plots simulated optical transfer loss as a function of the adiabatic taper length for the tapered waveguide structure of FIGS. 9B - 9C. The loss is determined based on a first amount of optical power input to the transition region in the first optical waveguide 911 and a second amount of optical power measured at the end of the transition region (end of second optical waveguide 913) that is coupled into a mode vertically spanning both the second optical waveguide 913 and optically active material 145. For the simulations of FIG. 10A through FIG. 10C, the optical wavelength was 1550 nm, the material for the first optical waveguide 911 was silicon nitride, the material for the second optical waveguide 913 was silicon nitride, the optically active material 145 was lithium niobate, and the cladding material between all waveguides was silicon dioxide

[0063] FIG. 11A depicts another implementation of tapered waveguide structure that can be formed in a heterogeneous photonics platform 100. The tapered waveguide structure is configured to transfer optical power between a lower dielectric optical waveguide 911 and a partially-etched, rib waveguide 1013 formed in the integrated optically active material 145. Cross-sectional views of the structure are also depicted for the three locations along the region marked with Roman numerals (i-iii).

[0064] FIG. 11B depicts another implementation of tapered waveguide structure that can be formed in a heterogeneous photonics platform 100. Optical power transfer can be between a lower dielectric optical waveguide 911 and a fully etched, strip waveguide 1015 formed inAttorney Docket No. BCNP-004W001the integrated optically active material 145. The strip waveguide 1015 can have a tapered end at the transition region. Cross-sectional views of the structure are also depicted for the two locations along the transition region marked with Roman numerals (i, ii).

[0065] FIG. 12A depicts regions of optical transparency for candidate waveguide, cladding, and electro-optic materials that could be used in the heterogeneous photonics platform 100. Silicon, silicon nitride, silicon dioxide, and lithium niobate exhibit low optical loss for wavelengths from about 1 micron to about 3.5 microns. FIG. 12B depicts a cross-sectional view of a silicon-nitride waveguide 913 optically coupled to an integrated thin film of lithium niobate 147. FIG. 12C plots simulated optical mode profiles for the geometry of FIG. 12B at three different infrared wavelengths. The same structure can provide single-mode operation over a large range of wavelengths.

[0066] FIG. 13 depicts, in cross-sectional view like FIG. 1, another implementation of a heterogeneous photonics platform 1300 in which a strip of resistive metal 1310 is also integrated directly above a waveguide 911 to act as a heater for thermo-optic tuning. The resistive metal 1310 can be incorporated into the other heterogeneous photonics platforms described herein.

[0067] FIG. 14 depicts an example implementation comprising the heterogeneous photonics platform 100 illustrated in FIG 1. In this implementation, a rare-earth seed laser 1410 is split and amplified into an array of waveguides (M x N waveguides in this example). Each of the waveguides can form an optical channel. The optical signal in each channel can be independently modulated with an electro-optical modulator in an array of E-0 modulators before being transmitted to other photonic elements via the output channels.

[0068] FIG. 15 depicts, in cross-sectional view like FIG. 1, another implementation of a heterogeneous photonics platform 1500 in which III-V material 1555 is integrated directly above and optically coupled to a waveguide 913. The III-V material 1555 can be microfabricated to comprise one or more p-n junctions and can be implemented as a photodetector, light-emitting diode, or semiconductor laser. The III-V material 1555 can be incorporated into the other heterogeneous photonics platforms described herein.

[0069] FIG. 16 depicts an example implementation comprising the heterogenous photonics platform 1500 illustrated in FIG. 15. In this implementation, the output from a rare-earth seed laser 1610 is modulated with one or more E-0 modulators 1620 and processed with signal processing photonic circuitry 1640 before being detected with integrated III-VAttorney Docket No. BCNP-004W001photodetectors 1660. The signal processing photonic circuitry 1640 imparts an amplitude and phase filter across the optical spectrum that is transferred to the output RF signals from the integrated III-V photodetectors 1660 to enable complex filtering, conjugation, and delay equalization.

[0070] FIG. 17 depicts, in cross-sectional view like FIG. 1, another implementation of a heterogeneous photonics platform 1700 in which III-V material 1755 is integrated such that it butt-couples to an optical waveguide. The butt coupling can be to an optical waveguide formed in the first microfabrication level 120 or the second microfabrication level 130 at a location out of the plane of the drawing and terminates at or in close proximity to the III-V material 1755 such that optical power from the optical waveguide couples to the III-V material 1755. The III-V material 1755 can be recessed into a trench formed in the first microfabrication level 120 and / or the second microfabrication level 130. The III-V material 1755 can be microfabricated to comprise one or more p-n junctions and can be implemented as a photodetector, light-emitting diode, or semiconductor laser. In some cases, the III-V material 1755 comprises a waveguide. The arrangement of butt-coupling into the III-V material 1755 can be incorporated into the other heterogeneous photonics platforms described herein.

[0071] FIG. 18 depicts an example implementation comprising the heterogenous photonics platform 1700 illustrated in FIG. 17. In this implementation, the output from an integrated III-V laser 1810 is amplified with a rare-earth doped waveguide 1820, modulated with one or more E-0 modulators 1840, and then processed with signal processing photonic circuitry 1860 before being detected with integrated III-V photodetectors 1880. The photodetectors 1880 can generate an RF signal that is output from the chip.

[0072] Heterogeneous integrated optical systems can be implemented and fabricated in different ways, some of which are listed below.(1) A heterogeneous integrated optical system comprising: a substrate; a first microfabrication level comprising a first optical waveguide disposed on the substrate; a second microfabrication level comprising a second optical waveguide disposed on the substrate, wherein the first microfabrication level is located between the substrate and the second microfabrication level; and an optically active material located on the substrate and arranged to optically couple to the first optical waveguide or the second optical waveguide, wherein the optically active material is an electro-optic material or a nonlinear opticalAttorney Docket No. BCNP-004W001material or a color-center-containing material and at least a portion of the first optical waveguide or at least a portion of the second optical waveguide is doped with a rare-earth ion or a transition metal ion to provide optical gain when the portion of the first optical waveguide or the portion of the second optical waveguide is optically pumped.(2) The heterogeneous integrated optical system of configuration (1), wherein: at least a portion of the first optical waveguide is doped with the rare-earth ion or the transition metal ion; the second optical waveguide is optically coupled to the first optical waveguide; and the optically active material is located to optically couple to the second optical waveguide.(3) The heterogeneous integrated optical system of configuration (1) or (2), wherein: the first optical waveguide extends into a region adjacent to the optically active material; and at least a portion of the second optical waveguide is located between a portion of the first optical waveguide that extends into the region adjacent to the optically active material and at least a portion of the optically active material.(4) The heterogeneous integrated optical system of any one of configurations (1) through (3), wherein the portion of the second optical waveguide forms a hybrid waveguide in combination with the optically active material.(5) The heterogeneous integrated optical system of any one of configurations (1) through (4), wherein the portion of the first optical waveguide that extends into the region adjacent to the optically active material comprises an adiabatic taper.(6) The heterogeneous integrated optical system of any one of configurations (1) through (5), wherein at least a first portion of the second optical waveguide directly contacts a second portion of the first optical waveguide.(7) The heterogeneous integrated optical system of configuration (6), wherein material used to form the first portion of the second optical waveguide is disposed adjacent to three sides of the second portion of the first optical waveguide.(8) The heterogeneous integrated optical system of any one of configurations (1) through (7), wherein at least a first portion of the optically active material directly contacts a second portion of the first optical waveguide or a second portion of the second optical waveguide.Attorney Docket No. BCNP-004W001(9) The heterogeneous integrated optical system of any one of configurations (1) through (8), wherein at least one of the first optical waveguide and the second optical waveguide comprises silicon nitride.(10) The heterogeneous integrated optical system of any one of configurations (1) through (9), wherein at least one of the first optical waveguide and the second optical waveguide comprises silicon.(11) The heterogeneous integrated optical system of any one of configurations (1) through (10), wherein the first optical waveguide is formed from a first material and the second optical waveguide is formed from a second material that is different from the first material.(12) The heterogeneous integrated optical system of any one of configurations (1) through (11), wherein the portion of the first optical waveguide or the portion of the second optical waveguide doped with the rare-earth ion or the transition metal ion is doped with a single species of a rare-earth element or a single species of a transition metal element.(13) The heterogeneous integrated optical system of any one of configurations (1) through (12), wherein the rare-earth ion comprises ionized erbium, ytterbium, thulium, neodymium, or praseodymium and the transition metal ion comprises ionized nickel, chromium, or titanium.(14) The heterogeneous integrated optical system of any one of configurations (1) through (13), wherein the portion of the first optical waveguide or the portion of the second optical waveguide doped with the rare-earth ion or the transition metal ion is doped with two or more species of rare-earth elements or two or more species of transition metal elements.(15) The heterogeneous integrated optical system of configuration (14), wherein the two or more species or rare-earth elements comprise erbium and ytterbium.(16) The heterogeneous integrated optical system of any one of configurations (1) through (15), wherein the second optical waveguide and additional optical waveguides formed in the second microfabrication level are not doped.(17) The heterogeneous integrated optical system of any one of configurations (1) through (16), wherein the optically active material comprises a third optical waveguide formed from the optically active material.Attorney Docket No. BCNP-004W001(18) The heterogeneous integrated optical system of configuration (17), wherein the optically active material comprises lithium niobate, lithium tantalate, or barium titanate.(19) The heterogeneous integrated optical system of any one of configurations (1) through (18), wherein at least a portion of the first optical waveguide is doped with the rare-earth ion or the transition metal ion; and the third optical waveguide is optically coupled directly to the first optical waveguide or the second optical waveguide.(20) The heterogeneous integrated optical system of any one of configurations (1) through (19), further comprising an integrated heater for thermo-optic tuning.(21) The heterogeneous integrated optical system of any one of configurations (1) through (20), further comprising a III-V semiconductor material disposed on the substrate.(22) The heterogeneous integrated optical system of configuration (21), further comprising a photodetector formed from the III-V semiconductor material.(23) The heterogeneous integrated optical system of any one of configurations (1) through (22), further comprising a semiconductor laser formed from the III-V semiconductor material.(24) The heterogeneous integrated optical system of any one of configurations (1) through (23), further comprising dielectric material disposed between the first optical waveguide and the second optical waveguide, wherein the dielectric material provides an optical cladding for the first optical waveguide and the second optical waveguide.(25) The heterogeneous integrated optical system of any one of configurations (1) through (24), wherein the portion of the first optical waveguide or the portion of the second optical waveguide doped with the rare-earth ion or the transition metal ion is doped with one or more species of rare-earth elements and one or more optically inactive dopants to increase incorporation of the rare-earth ion or the transition metal ion.(26) The heterogeneous integrated optical system of configuration (25), wherein the one or more optically inactive dopants comprise at least one of aluminum or phosphorus.(27) A method of fabricating a heterogeneous integrated optical system, the method comprising: forming, on a substrate, a first microfabrication level comprising a first opticalAttorney Docket No. BCNP-004W001waveguide; forming, on the substrate, a second microfabrication level comprising a second optical waveguide; disposing optically active material on the substrate, wherein the optically active material is located to optically couple to the first optical waveguide or the second optical waveguide; and doping at least a portion of the first optical waveguide or doping at least a portion of the second optical waveguide with a rare-earth ion or a transition metal ion to provide optical gain when the portion of the first optical waveguide or the portion of the second optical waveguide is optically pumped.(28) The method of (27), wherein doping at least the portion of the first optical waveguide or at least the portion of the second optical waveguide comprises implanting the rare-earth ion or the transition metal ion into a first region of first optical waveguide material in the first microfabrication level; and etching at least a first portion of the first optical waveguide in the first region of the first optical waveguide material; and / or implanting the rare-earth ion or the transition metal ion into a first region of second optical waveguide material in the second microfabrication level; and etching at least a first portion of the second optical waveguide in the first region of the second optical waveguide material.(29) The method of (27) or (28), wherein doping at least the portion of the first optical waveguide or at least the portion of the second optical waveguide comprises: depositing a first portion of waveguide material for the first optical waveguide or the second optical waveguide; performing a first patterned ion implantation into the first portion of the waveguide material; depositing a second portion of the waveguide material on the first portion of the waveguide material; and performing a second patterned ion implantation into the second portion of the waveguide material, wherein the second patterned ion implantation is aligned with the first patterned ion implantation to form the portion of the first optical waveguide or the portion of the second optical waveguide.(30) The method of any one of (27) through (29), wherein depositing the optically active material comprises bonding a die comprising the optically active material to the first microfabrication level or to the second microfabrication level.(31) The method of (30), wherein depositing the optically active material further comprises patterning the optically active material after bonding the die to form an optically active device for optical modulation.Attorney Docket No. BCNP-004W001(32) The method of any one of (27) through (31), wherein depositing the optically active material comprises bonding a wafer comprising the optically active material to the first microfabrication level or to the second microfabrication level.(33) The method of (32), wherein depositing the optically active material further comprises patterning the optically active material after bonding the wafer to form an optically active device for optical modulation.(34) The method of any one of (27) through (33), further comprising disposing color-center-containing material on the substrate, wherein the color-center-containing material is located to optically couple to the first optical waveguide or the second optical waveguide.(35) The method of any one of (27) through (34), wherein forming the second microfabrication level comprises directly contacting a first portion of the second optical waveguide to a second portion of the first optical waveguide.(36) The method of any one of (27) through (35), wherein disposing the optically active material comprises disposing at least a first portion of the optically active material to directly contact a second portion of the first optical waveguide or a second portion of the second optical waveguide.(37) The method of any one of (27) through (36), further comprising: disposing metal on the substrate to heat a region of the first optical waveguide or the second optical waveguide, or to provide electrical connection to an integrated optical device formed from the optically active material.(38) The method of any one of (27) through (37), wherein forming the first microfabrication level and forming the second microfabrication level comprises depositing dielectric material that is located between the first optical waveguide and the second optical waveguide and provides an optical cladding for the first optical waveguide and the second optical waveguide.

[0073] Conclusion

[0074] While various inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and / or structures for performing the function and / or obtaining the results and / or one or more of the advantages described herein, and each of such variations and / or modifications is deemed toAttorney Docket No. BCNP-004W001be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and / or configurations will depend upon the specific application or applications for which the inventive teachings is / are used. Those skilled in the art will recognize or be able to ascertain, using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that inventive embodiments may be practiced otherwise than as specifically described. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and / or methods, if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure.

[0075] Also, various inventive concepts may be embodied as one or more methods, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.

[0076] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0077] Unless stated otherwise, the terms “approximately” and “about” are used to mean within ± 20% of a target (e.g., dimension or orientation) in some embodiments, within ± 10% of a target in some embodiments, within ± 5% of a target in some embodiments, and yet within ± 2% of a target in some embodiments. The terms “approximately” and “about” can include the target. The term “essentially” is used to mean within ± 3% of a target.

[0078] The indefinite articles “a” and “an,” as used herein, unless clearly indicated to the contrary, should be understood to mean “at least one.”

[0079] The phrase “and / or,” as used herein, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should beAttorney Docket No. BCNP-004W001construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to a only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0080] As used herein, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of’ or “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e., “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” shall have its ordinary meaning as used in the field of patent law.

[0081] As used herein, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and / or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.Attorney Docket No. BCNP-004W001

[0082] In the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of’ and “consisting essentially of’ shall be closed or semiclosed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

Claims

Attorney Docket No. BCNP-004W001CLAIMS1. A heterogeneous integrated optical system comprising:a substrate;a first microfabrication level comprising a first optical waveguide disposed on the substrate;a second microfabrication level comprising a second optical waveguide disposed on the substrate, wherein the first microfabrication level is located between the substrate and the second microfabrication level; andan optically active material located on the substrate and arranged to optically couple to the first optical waveguide or the second optical waveguide, wherein the optically active material is an electro-optic material or a nonlinear optical material or a color-center-containing material and at least a portion of the first optical waveguide or at least a portion of the second optical waveguide is doped with a rare-earth ion or a transition metal ion to provide optical gain when the portion of the first optical waveguide or the portion of the second optical waveguide is optically pumped.

2. The heterogeneous integrated optical system of claim 1, wherein:at least a portion of the first optical waveguide is doped with the rare-earth ion or the transition metal ion;the second optical waveguide is optically coupled to the first optical waveguide; and the optically active material is located to optically couple to the second optical waveguide.

3. The heterogeneous integrated optical system of claim 2, wherein:the first optical waveguide extends into a region adjacent to the optically active material; andat least a portion of the second optical waveguide is located between a portion of the first optical waveguide that extends into the region adjacent to the optically active material and at least a portion of the optically active material.

4. The heterogeneous integrated optical system of claim 3, wherein:the portion of the second optical waveguide forms a hybrid waveguide in combination with the optically active material.Attorney Docket No. BCNP-004W0015. The heterogeneous integrated optical system of claim 3, wherein:the portion of the first optical waveguide that extends into the region adjacent to the optically active material comprises an adiabatic taper.

6. The heterogeneous integrated optical system of claim 1, wherein:at least a first portion of the second optical waveguide directly contacts a second portion of the first optical waveguide.

7. The heterogeneous integrated optical system of claim 6, wherein material used to form the first portion of the second optical waveguide is disposed adjacent to three sides of the second portion of the first optical waveguide.

8. The heterogeneous integrated optical system of claim 1, wherein:at least a first portion of the optically active material directly contacts a second portion of the first optical waveguide or a second portion of the second optical waveguide.

9. The heterogeneous integrated optical system of claim 1, wherein at least one of the first optical waveguide and the second optical waveguide comprises silicon nitride.

10. The heterogeneous integrated optical system of claim 1, wherein at least one of the first optical waveguide and the second optical waveguide comprises silicon.

11. The heterogeneous integrated optical system of claim 1, wherein the first optical waveguide is formed from a first material and the second optical waveguide is formed from a second material that is different from the first material.

12. The heterogeneous integrated optical system of claim 1, wherein the portion of the first optical waveguide or the portion of the second optical waveguide doped with the rare-earth ion or the transition metal ion is doped with a single species of a rare-earth element or a single species of a transition metal element.

13. The heterogeneous integrated optical system of claim 1, wherein the rare-earth ion comprises ionized erbium, ytterbium, thulium, neodymium, or praseodymium and the transition metal ion comprises ionized nickel, chromium, or titanium.

14. The heterogeneous integrated optical system of claim 1, wherein the portion of the first optical waveguide or the portion of the second optical waveguide doped with the rare-earthAttorney Docket No. BCNP-004W001ion or the transition metal ion is doped with two or more species of rare-earth elements or two or more species of transition metal elements.

15. The heterogeneous integrated optical system of claim 14, wherein the two or more species or rare-earth elements comprise erbium and ytterbium.

16. The heterogeneous integrated optical system of claim 1, wherein the second optical waveguide and additional optical waveguides formed in the second microfabrication level are not doped.

17. The heterogeneous integrated optical system of claim 1, wherein the optically active material comprises a third optical waveguide formed from the optically active material.

18. The heterogeneous integrated optical system of claim 17, wherein the optically active material comprises lithium niobate, lithium tantalate, or barium titanate.

19. The heterogeneous integrated optical system of claim 17, wherein:at least a portion of the first optical waveguide is doped with the rare-earth ion or the transition metal ion; andthe third optical waveguide is optically coupled directly to the first optical waveguide or the second optical waveguide.

20. The heterogeneous integrated optical system of claim 1, further comprising:an integrated heater for thermo-optic tuning.

21. The heterogeneous integrated optical system of claim 1, further comprising a III-V semiconductor material disposed on the substrate.

22. The heterogeneous integrated optical system of claim 21, further comprising a photodetector formed from the III-V semiconductor material.

23. The heterogeneous integrated optical system of claim 21, further comprising a semiconductor laser formed from the III-V semiconductor material.

24. The heterogeneous integrated optical system of claim 1, further comprising:dielectric material disposed between the first optical waveguide and the secondAttorney Docket No. BCNP-004W001optical waveguide, wherein the dielectric material provides an optical cladding for the first optical waveguide and the second optical waveguide.

25. The heterogeneous integrated optical system of claim 1, wherein the portion of the first optical waveguide or the portion of the second optical waveguide doped with the rare-earth ion or the transition metal ion is doped with one or more species of rare-earth elements and one or more optically inactive dopants to increase incorporation of the rare-earth ion or the transition metal ion.

26. The heterogeneous integrated optical system of claim 25, wherein the one or more optically inactive dopants comprise at least one of aluminum or phosphorus.

27. A method of fabricating a heterogeneous integrated optical system, the method comprising:forming, on a substrate, a first microfabrication level comprising a first optical waveguide;forming, on the substrate, a second microfabrication level comprising a second optical waveguide;disposing optically active material on the substrate, wherein the optically active material is located to optically couple to the first optical waveguide or the second optical waveguide; anddoping at least a portion of the first optical waveguide or doping at least a portion of the second optical waveguide with a rare-earth ion or a transition metal ion to provide optical gain when the portion of the first optical waveguide or the portion of the second optical waveguide is optically pumped.

28. The method of claim 27, wherein doping at least the portion of the first optical waveguide or at least the portion of the second optical waveguide comprises:implanting the rare-earth ion or the transition metal ion into a first region of first optical waveguide material in the first microfabrication level; andetching at least a first portion of the first optical waveguide in the first region of the first optical waveguide material; and / orimplanting the rare-earth ion or the transition metal ion into a first region of second optical waveguide material in the second microfabrication level; andAttorney Docket No. BCNP-004W001etching at least a first portion of the second optical waveguide in the first region of the second optical waveguide material.

29. The method of claim 27, wherein doping at least the portion of the first optical waveguide or at least the portion of the second optical waveguide comprises:depositing a first portion of waveguide material for the first optical waveguide or the second optical waveguide;performing a first patterned ion implantation into the first portion of the waveguide material;depositing a second portion of the waveguide material on the first portion of the waveguide material; andperforming a second patterned ion implantation into the second portion of the waveguide material, wherein the second patterned ion implantation is aligned with the first patterned ion implantation to form the portion of the first optical waveguide or the portion of the second optical waveguide.

30. The method of claim 27, wherein depositing the optically active material comprises: bonding a die comprising the optically active material to the first microfabrication level or to the second microfabrication level.

31. The method of claim 30, wherein depositing the optically active material further comprises:patterning the optically active material after bonding the die to form an optically active device for optical modulation.

32. The method of claim 27, wherein depositing the optically active material comprises: bonding a wafer comprising the optically active material to the first microfabrication level or to the second microfabrication level.

33. The method of claim 32, wherein depositing the optically active material further comprises:patterning the optically active material after bonding the wafer to form an optically active device for optical modulation.

34. The method of claim 27, further comprising:disposing color-center-containing material on the substrate, wherein the color-center-Attorney Docket No. BCNP-004W001containing material is located to optically couple to the first optical waveguide or the second optical waveguide.

35. The method of claim 27, wherein forming the second microfabrication level comprises:directly contacting a first portion of the second optical waveguide to a second portion of the first optical waveguide.

36. The method of claim 27, wherein disposing the optically active material comprises disposing at least a first portion of the optically active material to directly contact a second portion of the first optical waveguide or a second portion of the second optical waveguide.

37. The method of claim 27, further comprising:disposing metal on the substrate to:heat a region of the first optical waveguide or the second optical waveguide; or provide electrical connection to an integrated optical device formed from the optically active material.

38. The method of claim 27, wherein forming the first microfabrication level and forming the second microfabrication level comprises depositing dielectric material that is located between the first optical waveguide and the second optical waveguide and provides an optical cladding for the first optical waveguide and the second optical waveguide.

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