Coherent said on Wednesday optical fiber firm Lumentum Holdings had raised its offer for the company to $6.9 billion following a three-way takeover battle for the laser firm.
Under its new bid, Coherent shareholders will receive $220 in cash and 0.61 Lumentum shares for each share held.
Coherent agreed to a $5.7 billion deal with Lumentum in January, attracting other bidders looking to grow their share of a market, which is set to benefit from the rising adoption of 5G and consumer electronics.
Last month, MKS Instruments offered $6 billion, followed by a $6.4 billion bid by optical components maker II-VI.
Ever since, Lumentum and II-VI have engaged in a bidding war, making at least two counteroffers each by sweetening the cash component.
Lumentum also said private-equity firm Silver Lake would make a $1 billion equity investment in the combined company.
II-VI did not immediately respond to a request for comment.