Snapshot

Two products live under this heading. Fiber optic preforms are cylinders of ultra-pure silica glass, typically 1-2 meters long, that get heated and drawn into hair-thin optical fiber strands — each preform yields roughly 7,000-15,000 km of fiber. Specialty glass includes photomask substrates for chipmaking, Gorilla Glass for devices, and advanced optical glass. The two public companies that matter here are Corning (GLW), which dominates preform manufacturing and reported $6.3B in Optical Communications revenue in FY2025 (+35% YoY), and Coherent (COHR), which makes photonic components — lasers, transceivers, silicon photonics — and reported $1.8B in its most recent quarter (Q3 FY2026), with datacenter & communications at ~75% of revenue growing >40% YoY. Corning trades at $200.40 / $172.5B market cap; Coherent at $426.89 / $83.5B market cap.

AI GPU racks consume 16-36x more fiber than traditional server racks. Corning has locked in $18B+ in multi-year hyperscaler fiber agreements (Meta $6B + two others described as comparable) and is expanding US fiber capacity by 50%+. Coherent received a $2B NVIDIA equity investment plus a multi-billion-dollar purchase commitment for optical components. Corning capex ~$1B/yr; Coherent $290M in Q3 alone and rising. At least one major manufacturer has sold its entire fiber inventory through 2026.

The product & how money is made

Fiber optic preforms → fiber → cable (Corning's core)

A preform is manufactured via vapor deposition — Corning uses the Outside Vapor Deposition (OVD) process it invented — where layers of ultra-pure silica are deposited onto a rotating target rod, then consolidated into a solid glass cylinder. That cylinder is heated in a draw tower to ~2,000°C and pulled into fiber as thin as 125 microns. Corning sells the resulting fiber, cable (fiber bundled with protective jackets — now up to 1,728+ strands per cable), and connectivity products (connectors, panels, hardware). Corning's Optical Communications segment generated $6.274B in FY2025 revenue with segment net income of $1.048B (16.7% margin), up from $612M the prior year.

The Springboard Plan (upgraded May 2026) targets $30B total Corning sales by end-2028 and $40B by end-2030, up from a ~$16.4B FY2025 base. Optical Communications is the primary growth driver. A new Photonics Market-Access Platform (MAP) targets co-packaged optics — optical transceivers moved inside switch packages — which Corning estimates could be a $10B revenue stream by 2030 from zero today. est.

Photonic components — transceivers, lasers, silicon photonics (Coherent's core)

Coherent makes the active components that send and receive light through fiber: lasers (indium phosphide, silicon photonics), optical transceivers (800G shipping, 1.6T ramping), and optical circuit switches. Coherent's Datacenter & Communications segment is ~75% of revenue (~$1.35B of $1.8B in Q3 FY2026), growing 37% YoY for data center and 60% for communications. The company is transitioning from 3-inch to 6-inch indium phosphide wafers, which yield >4x as many devices at less than half the cost.

Revenue flow: hyperscalers and data center operators buy fiber/cable from Corning and transceivers/lasers from Coherent. Both are capital goods purchased during construction and upgrades, not consumables. Revenue is lumpy and tied to build cycles.

Demand

Contracted demand

• Corning — Meta agreement: up to $6B, multi-year, covering optical fiber, cable, and connectivity for US AI data centers. Meta is anchor customer for a new cable manufacturing facility in Hickory, NC. contracted
• Corning — two additional hyperscaler agreements: described as "similar in size and duration" to the Meta deal, announced Q1 2026 earnings. If comparable, that implies an additional ~$12B in contracted commitments. est. contracted
• Corning — NVIDIA partnership: NVIDIA purchased $500M in pre-funded warrants for 3M Corning shares, plus warrants for up to 15M more shares at $180/share (~$3.2B total if fully exercised). Underpins the Photonics MAP platform for co-packaged optics. contracted
• Coherent — NVIDIA strategic partnership: $2B equity investment plus a multi-billion-dollar purchase commitment for advanced laser and optical networking products, extending through the end of the decade. contracted
• Coherent backlog: record bookings in Q3 FY2026 with orders extending into calendar 2028 and long-term agreements through end of the decade. Management stated customer LTAs include upfront capital investment for capacity expansion. contracted

Demand forecasts

• US fiber infrastructure: 159.6 million fiber-miles installed today; projected need of 372.9 million fiber-miles by 2029 — a 134% increase, requiring 213 million additional fiber-miles. est.
• NVIDIA Blackwell 72-GPU nodes require 16x more fiber than traditional cloud switch racks (Corning's John McGirr). AI racks broadly need ~36x more fiber than CPU-based racks (STL CEO). est.
• Corning expects optical content demand per GPU to grow 1.3-1.5x faster than GPU unit growth through 2028.
• A third optical switching layer becomes necessary when AI clusters exceed ~130,000 GPUs, adding 50% more Corning content per site.
• Coherent sees co-packaged optics (CPO) as a >$15B incremental TAM and optical circuit switching as >$4B. CPO scale-out begins H2 CY2026; scale-up in H2 CY2027. est.
• Coherent management guidance: "We expect fiscal '27 growth rate to exceed our fiscal '26 growth rate."

Supply

Preform & fiber capacity (Corning-centric)

• The preform market is consolidated: the top players collectively hold ~52% share. Key manufacturers: Corning (US, OVD process), Fujikura (Japan), Furukawa/OFS (Japan/US), Prysmian (Italy), YOFC (China), Sumitomo (Japan), Shin-Etsu (Japan), Hengtong (China), STL/Sterlite (India). Asia-Pacific accounts for 67% of global production.
• Corning is the largest single producer globally and operates two of the world's largest optical fiber and cable manufacturing facilities in North Carolina.
• Corning capacity expansion underway: three new manufacturing facilities in North Carolina and Texas, increasing US optical connectivity capacity by 10x and US fiber production capacity by >50%, creating 3,000+ jobs.
• Preform manufacturing expansion takes 18-24 months from investment decision to output.
• At least one major fiber manufacturer has sold its entire fiber inventory through 2026.

Photonic component capacity (Coherent-centric)

• Coherent is doubling indium phosphide wafer capacity, expected complete one quarter early (by end of June 2026 quarter). Plans to more than double again by end of CY2027 — a ~4x increase over two years.
• 6-inch wafer ramp at three sites: Sherman TX (operational), Sweden (operational), Zurich (production starting early CY2027).
• First transceivers with 6-inch components shipped in Q3 FY2026.
• Coherent capex: $290M in Q3 FY2026 (up from $154M prior quarter and $112M year-ago), expected to increase further in Q4. TTM capex ~$679M against TTM revenue of $6.6B (10.3% of revenue).
• Binding constraint for transceivers: InP (indium phosphide) and silicon photonics wafer fabrication capacity — concentrated in a few fabs globally.

Bottlenecks

• Preform vapor deposition equipment: specialized capital equipment with limited manufacturers, long lead times.
• Ultra-pure silica supply: the raw input for preforms requires extreme purity levels.
• Draw tower capacity: each tower represents ~$50-100M investment and months of commissioning. est.
• InP wafer capacity: the semiconductor material for high-performance lasers; Coherent is one of few producers at scale.
• Skilled labor: both preform manufacturing and photonic component fabrication require specialized workers; Corning projecting 3,000+ new hires.

The gap

Pricing signals: Corning's Optical Communications segment net income grew 71% on 35% revenue growth in FY2025 — margins expanded, not compressed. Coherent's non-GAAP gross margin improved in 7 of the past 8 quarters, totaling ~530 bps of expansion, with a long-term target above 42%. The 1.6T transceiver ramp is "beneficial to gross margin" per Coherent management.

Data center fiber demand is currently ~5% of global optical cable demand (CRU, 2025). As AI clusters scale beyond 130,000 GPUs and require a third optical switching layer, fiber content per site increases another 50%. Capacity expansion takes 18-24 months from investment to output.

The players

Corning is diversified — Optical Communications is 38% of total revenue — so buying GLW includes exposure to display glass, auto glass, solar, and life sciences. Coherent is more concentrated at ~75% datacenter/comms after divesting aerospace & defense, with negative free cash flow during heavy capacity buildout.

The price of exposure

Corning (GLW) at $200.40

• $172.5B market cap ($180.6B enterprise value including $8.2B net debt) for $1.81B TTM net income and $1.50B TTM free cash flow.
• At the FY2025 Optical Communications run-rate ($6.3B revenue, $1.05B segment income), the implied price is ~$29 per dollar of Optical Comms segment profit — plus four other segments generating ~$10B of additional revenue.
• Springboard plan targets $30B revenue by end-2028 (high-confidence: $27B) and $40B by end-2030 (high-confidence: $35B), with 20%+ operating margins. At $35B revenue and 20% operating margins, that is $7B operating income — the current $180.6B EV would be ~26x that operating income. est.
• Stock has risen +304% over the past 52 weeks.
• Book value: $13.02/share — trades at 15.4x book.
• Annual dividend: ~$1.26/share (0.63% yield). No significant buyback program disclosed.

Coherent (COHR) at $426.89

• $83.5B market cap ($84.5B enterprise value including $0.4B net debt) for $6.6B TTM revenue, $401M TTM net income, and negative $538M free cash flow (heavy capex for InP and 6-inch wafer expansion).
• Q3 FY2026 non-GAAP EPS was $1.41; Q4 guide midpoint is $1.62. If Q4 delivers, FY2026 non-GAAP EPS run-rate would be ~$5.20-5.50, putting the stock at ~78-82x FY2026 non-GAAP earnings. est.
• Management guided FY2027 revenue growth to exceed FY2026 growth rate (~21-27% pro forma). At 25% growth, FY2027 revenue would be ~$8.5B. At a 20% operating margin, that is $1.7B operating income — the current $84.5B EV would be ~50x that operating income. est.
• Stock has risen +464% over the past 52 weeks.
• Book value: $54.60/share — trades at 7.8x book.
• Debt leverage ratio dropped to 0.5x EBITDA (from 2.1x a year ago) after the NVIDIA investment and $437M debt repayment.
• No dividend. No buyback.

What to deep-dive next

• Corning 10-K (FY2025): Segment-level balance sheet data, capex by segment, preform capacity specifics, customer concentration.
• Coherent 10-K (FY2025, ended Jun 30 2025): Networking vs. lasers vs. materials segment breakdown, InP wafer capacity numbers, customer concentration, NVIDIA supply agreement terms.
• Corning May 2026 Investor Day materials: Springboard plan breakdown, Photonics MAP sizing, copper-to-optical transition timeline.
• Verify the "two additional hyperscaler" deal sizes: Corning described them as "similar in size and duration" to Meta's $6B but did not name the customers or confirm identical dollar amounts.
• Coherent free cash flow trajectory: Currently negative ($-538M TTM) due to InP capacity expansion. When does capex normalize? The 6-inch wafer yield advantage (>4x devices at <50% cost) should drive margin expansion once capacity is built.
• Chinese competition: YOFC and Hengtong produce preforms at scale and may undercut Western pricing in non-hyperscaler markets. Whether hyperscalers source from Chinese manufacturers or exclusively from Corning/Prysmian/Fujikura is not publicly disclosed.

Sources & confidence

• Corning FY2025 results — press release, Jan 2026. GAAP sales $15.6B, Optical Comms $6.3B. Source
• Corning Q1 2026 results — press release, Apr 28 2026. Optical Comms $1.85B (+36% YoY), two new hyperscaler agreements. Source
• Corning-Meta $6B agreement — press release, Jan 2026. Source
• Corning Springboard upgrade & NVIDIA partnership — May 2026 Investor Day. Source
• Coherent FY2025 results — press release, Aug 2025. Revenue $5.81B (+23%). Source
• Coherent Q3 FY2026 earnings call — May 6 2026. Revenue $1.8B record, datacenter ~75%, InP doubling, NVIDIA $2B investment. Source
• NVIDIA-Coherent partnership — press release, Mar 2026. $2B equity + multibillion purchase commitment. Source
• Market cap, P/E, balance sheet — stockanalysis.com, accessed Jun 2026. GLW · COHR
• Fiber preform market size ($6.7B, 24.5% CAGR) — GM Insights, 2025. est. Source
• US fiber-mile projections & AI fiber multipliers — IEEE ComSoc TechBlog, Dec 2025, citing Corning and STL executives. Source
• Data center share of global fiber demand (~5%) — CRU Group, 2025. Source
• Coherent revenue history — stockanalysis.com. Source

Data as of Jun 2, 2026. Prices from stockanalysis.com and company press releases. Forward P/E figures are consensus estimates.