Abstract: Various embodiments of improved PIN-type photodiodes are provided. In an example embodiment, the PIN-type photodiode includes a p-type contact; an n-type contact; a first absorbing layer disposed between the p-type contact and the n-type contact; and a second absorbing layer disposed between the first absorbing layer and the n-type contact. The first absorbing layer is characterized by a first absorption coefficient and the second absorbing layer is characterized by a second absorption coefficient. The second absorption coefficient is greater than the first absorption coefficient. In another example embodiment, the PIN-type photodiode includes a p-type contact; an n-type contact; a first absorbing layer disposed between the p-type contact and the n-type contact; and a non-absorbing accelerating layer disposed between absorbing layers and non-absorbing drift layer and the n-type contact.

Abstract: Various embodiments provide methods for fabricating a couplable electro-optical device. An example method comprises fabricating a pillar on a substrate by forming a lens spacer portion about an electro-optical component fabricated on the substrate; and adhering unshaped lens material to an exposed surface of the pillar. The exposed surface of the pillar is disposed opposite the substrate. The example method further comprises maintaining the unshaped lens material at a reflow temperature for a reflow time to allow the lens material to reflow into a formed lens shape, and curing the lens material to form an integrated lens having the formed lens shape secured to the lens spacer portion and formed about the electro-optical component on the substrate.

Abstract: A vertical-cavity surface-emitting laser (VCSEL) is provided that includes a mesa structure disposed on a substrate. The mesa structure defines an emission axis of the VCSEL. The mesa structure includes a first reflector, a second reflector, and a cascaded active region structure disposed between the first reflector and the second reflector. The cascaded active region structure includes a plurality of cascaded active region layers disposed along the emission axis, where each of the cascade active region layers includes an active region having multi-quantum well and/or dots layers (MQLs), a tunnel junction aligned with the emission axis, and an oxide confinement layer. The oxide confinement layer is disposed between the tunnel junction and MQLs, and has an electrical current aperture defined therein. The mesa structure defines an optical window through which the VCSEL is configured to emit light.

Abstract: A vertical-cavity surface-emitting laser (VCSEL) is provided that includes a mesa structure disposed on a substrate. The mesa structure defines an emission axis of the VCSEL. The mesa structure includes a first reflector, a second reflector, and a cascaded active region structure disposed between the first reflector and the second reflector. The cascaded active region structure includes a plurality of cascaded active region layers disposed along the emission axis, where each of the cascade active region layers includes an active region having multi-quantum well and/or dots layers (MQLs), a tunnel junction aligned with the emission axis, and an oxide confinement layer. The oxide confinement layer is disposed between the tunnel junction and MQLs, and has an electrical current aperture defined therein. The mesa structure defines an optical window through which the VCSEL is configured to emit light.

Abstract: Disclosed are a testing unit, system, and method for testing and predicting failure of optical receivers. The testing unit and system are configured to apply different values of current, voltage, heat stress, and illumination load on the optical receivers during testing. The test methods are designed to check dark current, photo current, forward voltage, and drift over time of these parameters.

Abstract: Optical components and associated methods of manufacturing are provided. An example optical component includes a body defined by an optical interposer substrate and a passivation layer applied to the optical interposer substrate. The optical interposer substrate defines a first surface of the body, and the passivation layer defines a second surface of the body opposite the first surface. The passivation layer includes a metallic shielding element configured to prevent interference between the first surface and the second surface. The optical component further includes an opening extending from the second surface to the optical interposer substrate, the opening defining an optical path through the passivation layer. The optical interposer substrate receives an optical signal from an optical transmitter supported by the second surface via the optical path.

Abstract: A vertical-cavity surface-emitting laser (VCSEL) is provided that includes a mesa structure disposed on a substrate. The mesa structure defines an emission axis of the VCSEL. The mesa structure includes a first reflector, a second reflector, and a cascaded active region structure disposed between the first reflector and the second reflector. The cascaded active region structure includes a plurality of cascaded active region layers disposed along the emission axis, where each of the cascade active region layers includes an active region having multi-quantum well and/or dots layers (MQLs), a tunnel junction aligned with the emission axis, and an oxide confinement layer. The oxide confinement layer is disposed between the tunnel junction and MQLs, and has an electrical current aperture defined therein. The mesa structure defines an optical window through which the VCSEL is configured to emit light.

Abstract: A VCSEL includes an active region between a top distributed Bragg reflector (DBR) and a bottom DBR each having alternating GaAs and AlGaAs layers. The active region includes quantum wells (QW) confined between top and bottom GaAs-containing current-spreading layers (CSL), an aperture layer having an optical aperture and a tunnel junction layer above the QW. A GaAs intermediate layer configured to have an open top air gap is disposed over a boundary layer of the active region and the top DBR. The air gap is made wider than the optical aperture and has a height equal to one quarter of VCSEL's emission wavelength in air. The top DBR is attached to the intermediate layer by applying wafer bonding techniques. VCSEL output, the air gap, and the optical aperture are aligned on the same optical axis. The bottom DBR is epitaxially grown on a silicon or a GaAs substrate.

Abstract: Various embodiments provide methods for fabricating a couplable electro-optical device. An example method comprises fabricating a pillar on a substrate by forming a lens spacer portion about an electro-optical component fabricated on the substrate; and adhering unshaped lens material to an exposed surface of the pillar. The exposed surface of the pillar is disposed opposite the substrate. The example method further comprises maintaining the unshaped lens material at a reflow temperature for a reflow time to allow the lens material to reflow into a formed lens shape, and curing the lens material to form an integrated lens having the formed lens shape secured to the lens spacer portion and formed about the electro-optical component on the substrate.

Abstract: Several VCSEL devices for long wavelength applications in wavelength range of 1200-1600 nm are described. These devices include an active region between a semiconductor DBR on a GaAs wafer and a dielectric DBR regrown on the active region. The active region includes multi-quantum layers (MQLs) confined between the active n-InP and p-InAlAs layers and a tunnel junction layer above the MQLs. The semiconductor DBR is fused to the bottom of the active region by a wafer bonding process. The design simplifies integrating the reflectors and the active region stack by having only one wafer bonding followed by regrowth of the other layers including the dielectric DBR. An air gap is fabricated either in an n-InP layer of the active region or in an air gap spacer layer on top of the semiconductor DBR. The air gap enhances optical confinement of the VCSEL. The air gap may also contain a grating.

Abstract: Methods for fabricating vertical cavity surface emitting lasers (VCSELs) on a large wafer are provided. An un-patterned epi layer form is bonded onto a first reflector form. The first reflector form includes a first reflector layer and a wafer of a first substrate type. The un-patterned epi layer form includes a plurality of un-patterned layers on a wafer of a second substrate type. The first and second substrate types have different thermal expansion coefficients. A resulting bonded blank is substantially non-varying in a plane that is normal to an intended emission direction of the VCSEL. A first regrowth is performed to form first regrowth layers, some of which are patterned to form a tunnel junction pattern. A second regrowth is performed to form second regrowth layers. A second reflector form is bonded onto the second regrowth layers, wherein the second reflector form includes a second reflector layer.

Abstract: Various embodiments provide a method for fabricating a couplable electro-optical device. In an example embodiment, the method includes fabricating at least one raw electro-optical device on a substrate; applying lens material to a working stamp; aligning the substrate and the working stamp; pressing the substrate onto the lens material until the distance between the substrate and the working stamp is a predetermined distance; and curing the lens material to form an integrated lens secured to the at least one electro-optical device on the substrate. An anti-reflective coating layer may be optionally applied on top of the molded lens. The couplable electro-optical device may be incorporated into a receiver, transmitter, and/or transceiver using passive alignment to align the couplable electro-optical device to an optical fiber.

Abstract: Various embodiments of improved PIN-type photodiodes are provided. In an example embodiment, the PIN-type photodiode includes a p-type contact; an n-type contact; a first absorbing layer disposed between the p-type contact and the n-type contact; and a second absorbing layer disposed between the first absorbing layer and the n-type contact. The first absorbing layer is characterized by a first absorption coefficient and the second absorbing layer is characterized by a second absorption coefficient. The second absorption coefficient is greater than the first absorption coefficient. In another example embodiment, the PIN-type photodiode includes a p-type contact; an n-type contact; a first absorbing layer disposed between the p-type contact and the n-type contact; and a non-absorbing accelerating layer disposed between absorbing layers and non-absorbing drift layer and the n-type contact.

Abstract: A universal multi-core fiber (UMCF) interconnect includes multiple optical fiber cores and a shared cladding. Each of the optical fiber cores is configured to convey first optical communication signals having a first carrier wavelength using multi-mode propagation, and to convey second optical communication signals having a second carrier wavelength using single-mode propagation. The shared cladding encloses the multiple optical fiber cores.

Abstract: Several VCSEL devices for long wavelength applications in wavelength range of 1200-1600 nm are described. These devices include an active region between a semiconductor DBR on a GaAs wafer and a dielectric DBR regrown on the active region. The active region includes multi-quantum layers (MQLs) confined between the active n-InP and p-InAlAs layers and a tunnel junction layer above the MQLs. The semiconductor DBR is fused to the bottom of the active region by a wafer bonding process. The design simplifies integrating the reflectors and the active region stack by having only one wafer bonding followed by regrowth of the other layers including the dielectric DBR. An air gap is fabricated either in an n-InP layer of the active region or in an air gap spacer layer on top of the semiconductor DBR. The air gap enhances optical confinement of the VCSEL. The air gap may also contain a grating.

Abstract: Optical components and associated methods of manufacturing are provided. An example optical component includes a body defined by an optical interposer substrate and a passivation layer applied to the optical interposer substrate. The optical interposer substrate defines a first surface of the body, and the passivation layer defines a second surface of the body opposite the first surface. The passivation layer includes a metallic shielding element configured to prevent interference between the first surface and the second surface. The optical component further includes an opening extending from the second surface to the optical interposer substrate, the opening defining an optical path through the passivation layer. The optical interposer substrate receives an optical signal from an optical transmitter supported by the second surface via the optical path.

Abstract: Disclosed are a testing unit, system, and method for testing and predicting failure of optical receivers. The testing unit and system are configured to apply different values of current, voltage, heat stress, and illumination load on the optical receivers during testing. The test methods are designed to check dark current, photo current, forward voltage, and drift over time of these parameters.

Abstract: A system includes a pair of network devices, a universal multi-core fiber (UMCF) interconnect, and a pair of wavelength-division multiplexing (WDM) devices. Each network device includes (i) first optical communication devices configured to communicate first optical signals having a first carrier wavelength and (ii) second optical communication devices configured to communicate second optical signals having a second carrier wavelength. The universal multi-core fiber (UMCF) interconnect includes multiple cores that are configured to convey the first optical signals and the second optical signals between the network devices, using single-mode propagation for the first optical signals and multi-mode propagation for the second optical signals. Each WDM device is connected between a respective network device and the UMCF interconnect and configured to couple the first and second optical communication devices of the respective network device to the cores in accordance with a defined channel assignment.

Abstract: A universal multi-core fiber (UMCF) interconnect includes multiple optical fiber cores and a shared cladding. Each of the optical fiber cores is configured to convey first optical communication signals having a first carrier wavelength using multi-mode propagation, and to convey second optical communication signals having a second carrier wavelength using single-mode propagation. The shared cladding encloses the multiple optical fiber cores.

Abstract: Methods for fabricating vertical cavity surface emitting lasers (VCSELs) on a large wafer are provided. An un-patterned epi layer form is bonded onto a first reflector form. The first reflector form includes a first reflector layer and a wafer of a first substrate type. The un-patterned epi layer form includes a plurality of un-patterned layers on a wafer of a second substrate type. The first and second substrate types have different thermal expansion coefficients. A resulting bonded blank is substantially non-varying in a plane that is normal to an intended emission direction of the VCSEL. A first regrowth is performed to form first regrowth layers, some of which are patterned to form a tunnel junction pattern. A second regrowth is performed to form second regrowth layers. A second reflector form is bonded onto the second regrowth layers, wherein the second reflector form includes a second reflector layer.