CIOE 2026 Visit Notes — China International Optoelectronic Expo, Shenzhen

On-site notes taken 2026-09-11 at CIOE 2026 (Shenzhen World Exhibition & Convention Center), organised by vendor. Photos are in images/.

GoerTek Optics

This year's highlight: waveguide gratings made directly by DUV lithography, replacing the nanoimprint (NIL) route.

Process difference (as explained at the booth):

• Conventional route: gratings are made by nanoimprint lithography (NIL); the imprint master must first be written by EBL (electron-beam lithography).
• DUV route: no master needed — expose directly with DUV, then etch the grating.

Exhibit: Micro LED glass-etched full-colour waveguide module. One spec card compares NIL etching (left eye) and DUV etching (right eye) side by side:

The DUV-etched version measures better: contrast 70:1 vs 60:1, MTF 60% vs 50%; colour uniformity is the same.

GlaxReality

Key point: their AR waveguides do not use the common SRG (surface-relief grating). They use PVG (Polarization Volume Grating), fabricated from liquid crystal.

Asked how PVG differs from a conventional surface-relief grating, the booth answered:

1. Less visible — the grating is much less noticeable on the glass substrate (this is what the "Invisible Grating" selling point in the catalogue refers to).
2. Potentially higher efficiency — it is a volume-hologram-type grating.

The catalogue also lists photopolymer materials and array (geometric) waveguide modules, but PVG is the main product.

Catalogue contents, three product families:

• Optical Materials: photopolymers — HOE-G 3700, HOE-R 3700, HOE-B 3700 (pp. 7–9)
• Array Waveguide Modules: W2D30, M2026S, M2026N, M2030Q, M3050 (pp. 11–15)
• PVG Waveguide Modules: H2026G (p. 17), H2025G (p. 18), H2030C (p. 19), H2026GM (p. 20)

PVG waveguide modules, four models (catalogue pp. 17–20):

Marketing points: all four stress minimal rainbow artifacts, low light leakage and low cost. H2026G / H2026GM add "invisible grating" and "slim & lightweight"; H2025G is positioned on ultra-high optical efficiency (1200 nits/lm), full lamination and ultra-thin design (0.6 mm); H2030C (full colour) claims a simple process and better colour uniformity.

The booth also mentioned that the grating is written by two-beam interference, and that the liquid crystal aligns itself according to the interference field.

PVG fabrication primer (looked up after the visit, 2026-09-11)

Typical three-step flow:

1. Photo-alignment layer: a photosensitive alignment material (commonly an azo dye such as brilliant yellow) is coated on the glass substrate.
2. Polarization interference exposure: two circularly polarised laser beams interfere. The result is not a bright/dark fringe pattern but a field whose linear polarisation direction rotates periodically; the alignment-layer molecules follow this pattern, "writing" the grating into the alignment layer.
3. Liquid-crystal coating + UV curing: a reactive mesogen (polymerisable LC) doped with a chiral agent is coated on top. The LC self-assembles following the alignment pattern, the chiral dopant twists it into a helix through the thickness (giving a slanted grating), and UV polymerisation fixes the structure.

So "the LC aligns itself to the light field" is roughly right, but more precisely: the interference exposure records a polarisation pattern in the surface alignment layer, and the LC then self-assembles on that template and extends it into the bulk via the chiral dopant. The intuition that "the surface needs a guiding structure" is also correct — the guide is just a photo-alignment layer rather than a relief structure. Curing is UV polymerisation. Literature reports diffraction efficiencies above 80% for RGB PVGs.

References: SEU / Optics Letters: LC-based PVG for full-colour waveguide displays, Reflective PVG for high-efficiency waveguide-coupling AR displays, MDPI: FoV performance of full-colour waveguide displays based on PVG

Reflective (array / geometric) waveguide vendors

Observation: a surprisingly large number of exhibitors make reflective (array) waveguides. The technology itself is easy to understand and there was not much hidden detail. After talking to several of them, the process is confirmed to be: stack multiple glass substrates, each interface carrying its own (partially reflective) coating, bond them, then cut at an angle. The challenge is essentially all on the manufacturing side (coating and stack/cut precision, yield).

WEIYU Optics

1D and 2D array waveguide modules:

WYM-2601 (2D array) copy: a proprietary bidirectional micro/nano structure array design that addresses optical efficiency loss, with an optimised process for high-yield mass production; compared with other solutions it claims larger FoV, better eyebox, better eye relief and lighter weight.

GZOT (Nanjing)

GZ030MCC series: AR module combining a 1D exit-pupil-expansion (1D EPE) array waveguide with a 0.30" colour OLED microdisplay, aimed at AI smart glasses.

FoV 30°, 1280×720, max eyebox luminance 1000 nits, eyebox 9×6 mm, eye relief 15 mm, contrast ≥100000:1, see-through transmittance ≥80%, luminance uniformity ≥70%, distortion ≤1%, single-lane MIPI, typical power 120 mW, 60 Hz, module weight ≤11.5 g, operating temperature −20 to 65 °C. (Jiangning District, Nanjing; gzot.com)

GermanLitho (Qingdao)

Nanoimprint lithography (NIL) equipment maker. Wandered in without a plan; nothing particularly unusual. Asked how the master is made: either photolithography or EBL.

Two equipment flyers:

• GL4 HE / GL8 HE / GL12 HE: 100 / 200 / 300 mm combined UV-imprint and hot-embossing NIL tools. Imprint accuracy better than 10 nm, aspect ratio better than 10:1, residual layer under 10 nm; UV-LED 365 nm (>1000 mW/cm², 2000 optional), exposure uniformity better than 90%; imprint pressure <50–80 bar, temperature room temp to 250 °C (±1 °C); manual wafer loading. Applications: DOE, AR/VR diffractive waveguides (including slanted gratings), wire-grid polarisers, metalenses, biochips, LED.
• GL300 CLIV-X Gen2: 200 / 300 mm pressure/vacuum-enhanced full-field fully automatic NIL tool (single station). Cassette-to-cassette automatic loading (200 mm open cassette / 300 mm FOUP), optical edge pre-alignment, vacuum + gas-pressure enhanced hard-to-hard ring-sequential contact (eliminates bubbles and particles, suppresses overlay distortion); substrates: silicon, glass, quartz, plastic, metal. Same precision figures as above (10 nm, 10:1, residual layer <10 nm).

(Qingdao GermanLitho Co., Ltd., germanlitho.com)

Grand Unified Optics (Shanghai)

A catalogue handed out in the aisle ("One-Stop Optical Component Selection Guide", Edition 5.0). An optics "general store" selling off-the-shelf components: 12,000+ SKUs, in-house precision manufacturing, one-stop stock supply — lenses, prisms, filters, stages, mounts for lab and system-integration use. Business model similar to Thorlabs / Edmund Optics (a Chinese peer is Daheng Optics).

MetaLenX (Shenzhen, Hall 1, booth 1A82)

Metalens company; booth slogan "AI photonics infrastructure leader". Impression after the conversation: a fairly complete product line, with products already in mass production.

• Maximum aperture: 22 mm.
• Mainly infrared, with visible-light versions as well.
• Products are essentially all hybrid: a conventional refractive lens combined with a metalens.
• Dispersion / achromatic correction: they say achromatic performance is good in the IR but still difficult in the visible. (Reason not clear on site. Likely explanation: IR applications are often narrow-band, e.g. 940 nm, or the wavelength is long and the fractional bandwidth small, so the group-delay compensation required is small; the visible must cover 400–700 nm, a large fractional bandwidth, and the dispersion engineering range of nanopillars is limited — the larger the aperture the harder it gets. To be verified.)
• Intelligence: the Face ID module of the iPhone 17 Pro already uses a metalens, reportedly made by Metalenz (USA); MetaLenX bought units to tear down and study. (Metalenz ships consumer metasurface optics with STMicroelectronics, so this is credible.)
• Transmittance (shared conclusion from the discussion): essentially unsolvable. A metalens achieves very high transmittance only at a specific incidence angle and wavelength; any deviation in wavelength or angle degrades it. Reaching smartphone camera lens grade is therefore very hard; but the enormous miniaturisation advantage gives it a real chance in less demanding applications.

A*STAR NSTIC (Singapore, Hall 3, booth 3A40-9)

NSTIC (National Semiconductor Translation and Innovation Centre) under Singapore's ASTAR. On display: a 5 mm visible-light metalens and a 5 cm mid-IR metalens* (the flyer lists the 5-cm metalens for hyperspectral imaging).

Flat / Meta Optics platform (flyer highlights):

• Materials by band: TiO₂ or SiN on glass (visible), a-Si on glass (near-IR), a-Si on Si (mid-IR); in development: Si-rich SiN on glass (visible), multilayer stacked metalenses.
• Double-side wafer processing (metalenses on both sides of the wafer).
• Flat lens with NA up to 0.99, wide-FoV lens up to 180°; modules: wide-FoV fingerprint, depth sensing, flat-optics colour camera.

In-line 12-inch flat lens wafer automatic measurement system (claimed to be the world's first dedicated wafer-scale flat-lens in-line inspection system):

• Measures focusing efficiency, focal length, FoV, PSF, MTF, light-field distribution, phase distribution, wavefront aberration; non-contact, non-destructive, AI-assisted.
• Samples: 12 / 8 / 6-inch wafers or chiplets; wavelength 0.4–1.6 µm (extendable); objectives 40X NA 0.75 / 60X NA 0.9; spatial resolution 0.37–0.45 µm; 127 MP camera; stage travel 302×302 mm, 0.1 µm step; full 12-inch focusing-efficiency map in about 20 minutes.
• Applications: QC for metalens / meta-optics mass production (TiO₂, SiN, a-Si), defect inspection of transparent wafers (SiC, GaN).

The other page covers Silicon Photonics: a PHI heterogeneous-integration platform (TFLN-on-SiN, 8/12-inch D2W bonding, hydrogen-free low-loss SiN, high-Q microrings for frequency combs) — off-topic for this visit, noted for completeness.

MetaXi Photonics (Wuhan)

Metasurface optics start-up (12-inch wafer-level mass-production capability; team background UC Berkeley, NTU Singapore, Tianjin University, HUST). Talked to them but did not learn much; two key points:

• One direction they are very interested in is colour routing (metasurface colour routers replacing the colour filter array on CMOS image sensors); but the hard part is that it requires cooperation with the CMOS sensor makers, and they could not share details.
• Their metalens products are presumably also mainly infrared.

Catalogue summary:

• Four core technologies: full-wave design/simulation, FFO (full-field, full-parameter optimisation), wafer-level mass-production process, meta-atom library.
• 3D sensing (main line, 940 nm NIR): Tx — dot projector (FoV 120°×90° / 90°×60°, beam splitting 19×7 / 6×3, uniformity >80%, efficiency >70%, integrated collimation with no separate collimator), flood illuminator (uniformity >85%), collimator (<0.1°, efficiency >90%); Rx — a single metasurface as thin as 0.2 mm replacing a conventional 2–3-element injection-moulded lens (FoV 45/60/85°, MTF >90% @30 lp/mm, integrated 930–970 nm OD3 narrow-band filter).
• Other lines: optical communications (1D/2D metasurface arrays replacing silicon / moulded-glass lens arrays for OCS/CPO/NPO data-centre interconnects), IR thermal imaging (refractive-meta hybrid lenses replacing Si/Ge elements to cut TTL and cost), visible-light hybrid lenses, custom design.