what are the best photonics stocks to buy?

The optical boom rewards different parts of the chain unequally

The demand case is substantial. LightCounting estimated approximately $18 billion of Ethernet optical-transceiver sales in 2025 and projected 73% growth in 2026. Applying that forecast to the estimated base implies roughly $31 billion of annual sales. The industry has ample room to grow; the investment question is how that growth converts into profits and cash. [6][7]

An optical link requires more than a laser. Component suppliers provide the devices that generate and process signals; module vendors combine them into products; manufacturers assemble and test them; fiber suppliers connect the infrastructure. Product qualification and scarce capacity can protect suppliers, while large buyers retain influence over architecture, purchasing and price. Fabrinet earns manufacturing revenue; Lumentum owns differentiated optical components and systems. Their economics consequently differ. [8][9]

NVIDIA supplied a concrete demonstration of where capacity matters. In March, it committed $2 billion of equity funding to each of Lumentum and Coherent alongside multiyear purchasing arrangements and future capacity-access rights. Coherent issued common shares; Lumentum issued convertible preferred shares. The customer helped finance the factories that would serve it. Those arrangements strengthen the demand case while putting execution and capital requirements squarely inside the suppliers’ investment cases. [10][11][8][12]

Our view is that Lumentum currently demonstrates the strongest direct optical economics. Fiscal-2026 revenue grew 83% to $3.01 billion, and fourth-quarter GAAP gross margin reached 47.4%. Annual operating cash flow of $751 million exceeded cash property-and-equipment payments of $451 million, leaving approximately $300 million. [5][8]

Expansion leaves markedly different amounts of cash available after property-and-equipment spending.

Sources: fiscal-2026 filings. Calculated as operating cash flow less cash PPE expenditure; acquisitions and other investing flows are excluded. [8][9][12]

The contrast is sharp. Fabrinet retained approximately $4 million after cash PPE purchases; Coherent consumed approximately $1.02 billion on the same basis. Factory construction can create valuable future capacity, so one year’s cash consumption cannot settle lifetime returns. It does tell us how much of the current expansion shareholders are financing. [9][12]

That is why our business ranking and purchase ranking diverge. We prefer Lumentum’s demonstrated optical economics, but the price of MKS requires a more manageable earnings outcome.

MKS offers the most manageable earnings hurdle, with debt attached

MKS serves semiconductor, electronics and photonics markets. Its diversified exposure means investors participate in more than optical networking. In the June quarter it reported $1.25 billion of revenue and adjusted EPS of $3.30, alongside GAAP EPS of $2.41. Management’s September-quarter adjusted EPS guidance was $3.58, plus or minus $0.31. [2]

Our central case assumes annual adjusted EPS reaches $18 after 2.5 years. Annualizing the guidance midpoint gives a $14.32 starting reference, so the required growth is about 9.6% a year. This is a plausible hurdle in our view, though it begins from a strong quarterly outlook and remains exposed to semiconductor cyclicality. [2]

At 20× those earnings, the exit share value is $360. Discounting that value at a 12% annual return over 2.5 years gives an entry threshold of $271.18—effectively the $271.24 reference price. Buying at $250 instead raises modeled annual appreciation to approximately 15.7%. We therefore prefer $240–260 rather than paying right up to the threshold. [1][2]

The reason to insist on a cushion is the balance sheet. MKS reported $1.40 billion of short-term debt and $2.54 billion of long-term debt against $611 million of cash. Adding both debt categories and subtracting cash gives approximately $3.33 billion of net debt. Strong earnings growth must also support that financial obligation. [2]

A modest reduction in the exit multiple moves the acceptable entry price well below the reference quote.

Source: MKS disclosures and our assumptions. Entry prices discount scenario exit values by 1.12 raised to 2.5; returns exclude dividends, taxes and costs. [2]

The downside deserves as much attention as the central case. An annual exit EPS outcome of $12 valued at 16× would produce a $192 share price, roughly 29% below the reference. Our upside scenario of $22 at 24× produces $528. Those wide boundaries explain why we regard MKS as a price-sensitive relative preference, rather than a financially conservative holding. [1][2]

Fabrinet offers production exposure, but its cash conversion must recover

For investors who specifically want optical-manufacturing exposure, we prefer Fabrinet at a better price. Its attraction is qualified production capacity serving multiple product owners. That reduces dependence on selecting a single winning module brand, although purchasing power remains concentrated among major customers. [9]

Fiscal-2026 revenue reached $4.64 billion. Datacenter products represented 47.9% of sales, encompassing a broader category than AI transceivers. Four customers each contributing at least a tenth of sales together accounted for 57.4% of revenue. Fourth-quarter GAAP gross margin was approximately 12%, calculated from gross profit of about $158 million on $1.32 billion of revenue. The manufacturer participates in the expansion, but its customers retain much of the product economics. [3][9]

Growth also requires funding. Inventory reached approximately $1.02 billion, and Fabrinet was developing a roughly two-million-square-foot Chonburi facility with an estimated project cost of $132.5 million. Annual operating cash flow of $256.7 million barely covered $252.5 million of cash PPE purchases. We want to see that cash conversion improve as the expansion matures. [9]

The earnings outlook gives us a basis for a purchase price. Management guided the following quarter to adjusted EPS of $4.10–4.25. Annualizing the midpoint gives $16.70. Our assumed annual exit EPS of $24 requires approximately 15.6% annual growth over 2.5 years. We apply 22× earnings, a restrained multiple reflecting manufacturing economics and customer concentration. That supports a purchase threshold near $398 and our preferred $380–400 range. [3]

At the $451.44 reference price, the same scenario produces only about 6.5% annual appreciation. We like the exposure, but would wait for a more favorable relationship between price and earnings—or evidence sufficient to raise our earnings case. [1][3]

IPG requires a recovery, not merely patience

IPG gives the shortlist a different source of demand. Industrial Solutions accounted for 85% of second-quarter revenue, with applications including welding, marking, cleaning and additive manufacturing. Total revenue grew 11% to $279 million, driven by 16% industrial growth. This is principally an industrial-laser investment. [4]

Our conviction is lower because the required earnings recovery is steeper. Quarterly adjusted EPS was $0.58, equivalent to $2.32 when annualized. Reaching our $4.50 annual exit EPS assumption requires approximately 30% annual growth over 2.5 years. At 22× earnings, the resulting $99 exit value supports an entry around $75. We prefer $70–75, compared with the $83.66 reference price. [4][1]

The balance sheet helps, but its cash has competing uses. IPG reported approximately $871 million of cash and short-term investments at June 30, then proposed purchasing Lumibird Medical for €300 million on a cash-free, debt-free basis. The target reported €112 million of 2025 revenue and €24.1 million of EBITDA. Investors must assess the earnings acquired alongside the liquidity spent. [4][13]

First-half operating cash flow of $32.3 million fell slightly short of $37.0 million of PPE spending. Sustained industrial growth and better cash generation would strengthen the recovery case. A large cash balance alone is insufficient reason for us to pay the current reference price. [4]

MKS requires less earnings growth from the quarterly reference than Fabrinet or IPG.

Sources: company disclosures. Our exit assumptions span 2.5 years; quarterly references are annualized guidance midpoints for MKS and Fabrinet, and latest reported adjusted EPS for IPG. [2][3][4]

Lumentum’s business leads; its valuation sets a much higher bar

The strongest challenge to our shortlist comes from the direct optical suppliers. If shortages persist and new products scale rapidly, their earnings may outrun the more diversified businesses. Lumentum’s growth, margins and cash generation give that argument substance. Its August outlook called for following-quarter revenue of $1.225–1.275 billion and a non-GAAP operating margin of 39.5–40.5%. [5]

We nevertheless prefer to watch the shares at the available reference price. At $1,045.78, a 12% annual appreciation requirement over 2.5 years translates into approximately $46.28 of annual exit EPS, assuming investors still pay 30× earnings. We derive that hurdle by growing the entry price at 12% and dividing by the exit multiple. A generous terminal valuation still demands substantial earnings. [1]

Those earnings must accrue to each existing share after financing and expansion. Lumentum’s two largest unnamed customers represented 26.6% and 15.0% of annual sales, while NVIDIA’s preferred investment introduces potential conversion dilution. We would reconsider at a substantially lower price or with credible evidence supporting earnings near the required hurdle after those obligations. [8]

Coherent presents a different tension: impressive vertical scope and demand alongside heavy cash consumption. Fiscal-2026 Datacenter & Communications revenue reached $5.27 billion, while total debt obligations stood at $3.22 billion. Its approximately $1.02 billion cash deficit after PPE additions makes returns on the expanded capacity central to the equity case. [12]

At Coherent’s $319.19 reference price and a 25× exit multiple, the same 12% return framework requires annual exit EPS of approximately $16.95. Reported fiscal-2026 adjusted EPS was $5.61. We want sustained positive cash flow after capital expenditure and evidence that new capacity earns attractive returns before moving it above our shortlist. [1][14]

AAOI remains a speculative candidate. Second-quarter datacenter revenue reached $107.7 million, but the company recorded a $24.7 million GAAP operating loss. Management described capacity approaching 200,000 monthly units and targeted approximately 650,000 monthly units of 800G and 1.6T capacity by year-end. That ambitious buildout still needs profitable utilization. [15]

The financing burden is substantial: first-half operating cash outflow of $73.8 million accompanied approximately $335 million of capital spending. Guidance already used approximately 92.8 million diluted shares. Our moderate-risk shortlist excludes AAOI until profitable shipments, improving operating cash flow and controlled dilution make the per-share outcome more convincing. [16][15]

Broader photonics offers alternatives, but diversification has a price

Jenoptik is our most interesting international watchlist alternative. First-half order intake grew 53% to €723 million, producing a 1.44 book-to-bill ratio. EBITDA rose 25.5% to €98.9 million while revenue increased only 1%. Improving orders and profitability give the case substance; converting the order book into sales and cash is the next test. [17][18]

The research’s indicative valuation of approximately 12–13.5× estimated normalized EBITDA makes it worth watching. That range uses estimated annual EBITDA of €208–235 million and approximately €2.82 billion enterprise value, built from the €43.84 European closing reference price, 57.24 million shares and €307.5 million net debt. We retain it on the watchlist pending an equally developed per-share return case. [1][18]

Exosens offers defense and detection exposure, with a 33% first-half adjusted EBITDA margin and €31.4 million of free cash flow. Its attractive operating profile earns attention, but does not give us reason to displace the shortlist. [19]

Corning demonstrates that broader exposure can still be closely linked to AI investment. Second-quarter Optical Communications sales grew 32% to $2.07 billion, including 65% growth in Enterprise Networks. Its Meta agreement carries a multiyear commitment ceiling of $6 billion for fiber, cable and connectivity. [20][21]

At Corning’s $160.42 reference price, however, a 25× exit multiple requires approximately $8.52 of annual exit EPS to meet our price-appreciation hurdle. The latest quarterly core EPS was $0.78. We recognize the operating momentum without treating diversification as a substitute for valuation discipline. [1][20]

MACOM, Novanta and Hamamatsu also remain worth monitoring. MACOM reported a 58.3% consolidated gross margin, though its datacenter end-market revenue encompasses more than optical devices. Novanta offers medical and automation exposure, while Hamamatsu’s growing group sales coexist with losses in its laser business. Our evidence does not support stronger purchase cases for these companies than the shortlist. [22][23][24][25]

Cash returns on new capacity will decide whether restraint pays

The strongest case against our view is straightforward: optical demand could grow fast enough that our earnings assumptions and exit multiples prove too conservative. NVIDIA’s financing commitments, Lumentum’s acceleration and the industry’s expansion forecast deserve substantial weight. We could miss further appreciation in the direct optical names while waiting for better prices. [10][11][5][7]

We give that argument more weight for business prospects than for purchase prices. Rapid demand growth, successful factory execution, limited dilution and premium exit multiples are related favorable assumptions. The equity case becomes fragile when it needs all of them.

For our ranking to hold, MKS must sustain a credible path toward $18 annual earnings while reducing its financial burden. Fabrinet must turn growing production into better cash conversion after its expansion. IPG must deliver an industrial recovery and acquisition returns that accrue to each share. A weaker earnings path, deteriorating debt service or cash spent without proportional returns would lower our purchase limits.

The direct optical suppliers can change that ranking. Lumentum needs a more favorable price or stronger evidence for fully diluted earnings near its valuation hurdle. Coherent needs the new capacity to generate sustained cash after capital expenditure. AAOI needs profitable shipments and a funded expansion with controlled dilution. Across the sector, faster price erosion, inventory accumulation or lost content in new architectures would push us the other way.

Customers have helped fund the optical expansion. The next test is what those factories earn for shareholders.