Search

US-12620778-B2 - Compact, surface-mounted VCSEL illuminators

US12620778B2US 12620778 B2US12620778 B2US 12620778B2US-12620778-B2

Abstract

VCSEL-based flood illuminators are fabricated to be compact and surface-mounted devices. A substrate is constructed as a panel array having top and bottom electrodes. Individual ones of the VCSEL dies are mounted in electrical communication with pairs of the top electrodes. The VCSEL dies are encased in an encasement disposed on the top surface of the substrate, and a diffuser structure is nano-imprinted adjacent each of the VCSEL dies. The encasement can use a potting resin and a polymer layer. The potting resin encases the VCSEL dies. The polymer layer is softer and is disposed on the potting resin. Nanoimprint lithography forms the diffuser structures in the polymer layer. The panel array is then singulated to form the individual VCSEL-based flood illuminators.

Inventors

  • Jason O'Daniel
  • Pei-Song Cai
  • Hong-Zhi LIU
  • Francesco Schiattone

Assignees

  • II-VI DELAWARE, INC.

Dates

Publication Date
20260505
Application Date
20220624

Claims (14)

  1. 1 . A flood illuminator, comprising: a substrate having bottom and top surfaces, the bottom surface having bottom electrodes, the top surface having top electrodes; a vertical-cavity surface-emitting laser (VCSEL) die mounted in electrical communication with the top electrodes and being configured to emit laser illumination; an encasement disposed on the top surface of the substrate and encasing the VCSEL die; and a diffuser structure nano-imprinted in the encasement adjacent the VCSEL die, wherein the encasement includes first and second layers, the first layer disposed on the top surface of the substrate and encasing the VCSEL die, and the second layer disposed on the first layer and having the diffuser structure nano-imprinted therein, wherein the first layer comprises a silicone-elastomer and has a Shore D hardness and the second layer has a Shore A hardness, the second layer being softer than the first layer.
  2. 2 . The flood illuminator of claim 1 , wherein the substrate comprises a bismaleimide triazine (BT) laminate, a ceramic substrate, or a lead frame.
  3. 3 . The flood illuminator of claim 1 , wherein the first layer comprises a potting resin; and the second layer comprises a polymer layer disposed on the potting resin.
  4. 4 . The flood illuminator of claim 1 , wherein the second layer comprises a silicone-elastomer or polydimethylsiloxane (PDMS).
  5. 5 . The flood illuminator of claim 1 , wherein the VCSEL die is mounted to one of the top electrodes and is wire-bonded to the other of the top electrodes.
  6. 6 . The flood illuminator of claim 1 , wherein the VCSEL die is flip-chip mounted on the top electrodes.
  7. 7 . The flood illuminator of claim 1 , wherein the substrate comprises vias connecting the bottom electrodes to the top electrodes.
  8. 8 . The flood illuminator of claim 1 , wherein the substrate comprises a solder mask separating the bottom electrodes.
  9. 9 . The flood illuminator of claim 1 , wherein the diffuser structure comprises one or more lenslets having a free-form surface configured to shape incident light into desired illumination or diffused profile.
  10. 10 . The flood illuminator of claim 9 , wherein the device has dimensions of 0.5 mm (W) by 0.5 mm (D) by 0.5 mm (H); wherein the encasement has a thickness of 0.3 mm; and wherein the diffuser structure is arranged at a working distance of 0.15 mm from the VCSEL die.
  11. 11 . The flood illuminator of claim 1 , wherein the diffuser structure comprises a plurality of lenslets having a pitch of 20 microns.
  12. 12 . The flood illuminator of claim 1 , further comprising a working distance between the VCSEL die and the diffuser structure is from 0.15 mm to 0.85 mm.
  13. 13 . An array of the flood illuminators of claim 1 , wherein the substrate of each flood illuminator is part of a common substrate that is shared among the array of flood illuminators.
  14. 14 . The array of the flood illuminators of claim 1 , wherein the first and second layers of each flood illuminators are part of common first and second layers that are shared among the array of flood illuminators.

Description

FIELD OF THE DISCLOSURE The subject matter of the present disclosure is directed to a flood illuminator for use in three-dimensional sensing and two-dimensional imaging. In particular, the subject matter is direct to a flood illuminator based on a vertical-cavity surface-emitting laser (VCSEL). BACKGROUND OF THE DISCLOSURE Flood illuminators are incorporated into various products, such as mobile phones and other devices, to provide 3D sensing capabilities, 3D mapping in robotics, face detection, etc. For example, FIG. 1 shows a flood illuminator 10, which can be incorporated within a mobile device or the like. The flood illuminator 10 has a vertical-cavity surface-emitting laser (VCSEL) 30 that modulates a flood beam emitted to a diffuser 46. In turn, the diffuser 46 produces a modulated floodlight having a uniform field of illumination of infrared (IR) light. The floodlight is output onto an object or person of interest (not shown), and an infrared camera (not shown) captures images of the depth signature from the modulated IR floodlight. The flood illuminator 10 based on the VCSEL 30 as shown here is being considered more and more as a replacement for conventional illuminators that are based on light-emitting diodes (LEDs). For example, the VCSEL-based flood illuminator is currently used in many 3D sensing time-of-flight applications. However, in some applications, the standard package for the VCSEL-based illuminator 10 is too large. For example, the standard package for the VCSEL-based flood illuminator 10 shown in FIG. 1 has the VCSEL 30 mounted on a substrate 20 to provide illumination. The substrate 20 has top and bottom electrode pads 22, 24. A housing 40 is mounted to the substrate 20 and includes sidewalls 44 supporting the diffuser 46, which is separated by an air cavity 42 above the VCSEL 30. The diffuser 46 is positioned at a minimum distance away from the VCSEL apertures to function properly. This arrangement protects the diffuser's surface, but the housing 40 holding the diffuser 46 requires a larger package. For harsh environments, the structure of this arrangement also needs to be robust to avoid the diffuser 46 from being cracked or detached. For a VCSEL-based flood illuminator to be suitable for use in some applications, the package for the VCSEL-based illuminator needs to be as small as possible. Still, the VCSEL-based illuminator needs an integrated beam shaping diffuser to provide a correct illumination pattern. The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above. SUMMARY OF THE DISCLOSURE A flood illuminator disclosed herein comprises a substrate, a vertical-cavity surface-emitting laser (VCSEL) die, an encasement, and a diffuser structure. The substrate has bottom and top surfaces. The bottom surface has bottom electrodes, and the top surface has top electrodes. The VCSEL die is mounted in electrical communication with the top electrodes and is configured to emit laser illumination. The encasement is disposed on the top surface of the substrate and encases the VCSEL die. The diffuser structure is nano-imprinted in the encasement adjacent the VCSEL die. A method disclosed herein is directed to fabricating flood illuminators. The method comprises: constructing a substrate in panel form having top electrodes on a top surface and having bottom electrodes on a bottom surface; mounting individual ones of vertical-cavity surface-emitting laser (VCSEL) dies in electrical communication with pairs of the top electrodes; encasing the VCSEL dies in an encasement disposed on the top surface of the substrate; and nano-imprinting a diffuser structure adjacent each of the VCSEL dies to form individual VCSEL-based flood illuminators. The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically illustrates a VCSEL-based flood illuminator according to the prior art. FIG. 2A illustrates a perspective view of a VCSEL-based flood illuminator according to the present disclosure. FIG. 2B illustrates a side view of the disclosed VCSEL-based flood illuminator. FIG. 3 illustrates another side view of the disclosed VCSEL-based flood illuminator with a flip-chip mounted VCSEL. FIG. 4 illustrates a panel-level assembly of VCSEL-based flood illuminators according to the present disclosure. FIGS. 5A-5E illustrate perspective, front, side, top, and bottom views of a BT-style package for a VCSEL-based flood illuminator according to the present disclosure. FIG. 6 illustrates a ceramic-type package for the VCSEL-based flood illuminator according to the present disclosure. DETAILED DESCRIPTION OF THE DISCLOSURE FIGS. 2A-2B illustrate perspective and side views of a VCSEL-based flood illuminator 50 according to the present disclosure. The illuminator 50 is configured as a chip-scale package (CSP) and is shown a