We’re into the Q&A portion of Coherent’s conference call and the first question is fishing for how much growth could be coming in the second half of 2026.
Here’s what was asked:
JPMorgan Chase & Co, Research Division
Yes. Jim hope your leg is healing now. Hopefully, things are better on that front. Maybe for the first question really just on demand, how would you characteristic? I mean you gave some of the book-to-bill numbers that you’re seeing, but how would you characterize the visibility there in terms of maybe duration?
Like how long is the visibility in terms of demand that the customers are providing and vis-a-vis how should we think about the capacity ramp for indium phosphide in particular, how are you planning that out, particularly how to think about contribution of 6-inch to that capacity ramp? And I have a follow-up.
Chief Executive Officer
Yes. Thanks, Samik. And yes, the leg is doing much better for that. I appreciate that. On the demand question, yes, I would say, I’d call the demand that we’re seeing and the visibility extraordinary. If I just look at a couple of highlights from last quarter. If we look at our data center business, I was really pleased with the acceleration of our sequential growth rate to 14% sequential growth. And then we also saw, as I mentioned in the prepared remarks, over 4x book-to-bill ratio.
So just seeing incredibly strong demand. And we’re seeing bookings go further out in time than we would have in the past, which is great for us for visibility. So number one, bookings being booked out through the rest of this calendar year. Most of the bookings we’re getting now are into calendar ’27.
So most of our calendar ’26 is booked out. And calendar ’27 is feeling very, very quickly. That’s important to us because it gives us just great visibility. And then we’re also getting really good detailed long-term forecast from our big customers. A lot of times, those forecasts go out 2, 3 years. So we’re getting forecast to go out into calendar ’28, which again is great for visibility.
And then the third thing I would mention with respect to visibility is a number of long-term supply agreements that we’ve either signed with customers or in the process of signing where the will provide a guarantee to our customers for a certain amount of supply in an exchange that give us a guarantee on a certain amount of demand. And there’s often some sort of financial commitment from our customers like investment for CapEx, et cetera.
So I would say all those things combined, the visibility of the business is the best it’s ever been, which gives us just kind of great confidence in terms of the go-forward growth that we’re seeing. On the second part of your question on indium phosphide capacity ramp, again, we’re really pleased with the team’s execution here on the 6-inch indium phosphide ramp. One of the key metrics that I look at in terms of how the progress — how we’re making progress is wafer starts.
And remember, our goal that we mentioned last quarter was that we wanted to double indium phosphide capacity by the end of this calendar year. And if you look at the number of wafer starts that were starting this quarter, we’re basically at 80% of that target capacity already. So we’re starting wafers at 80% of the goal of doubling capacity, which is really strong and, frankly, ahead of schedule. In fact, last quarter, we more than quadrupled the number of wafer starts from our September quarter to our December quarter.
So I think that, for me, that’s a really good, important leading indicator on how we’re progressing on the indium phosphide ramp is that be at 80% of target in terms of initial wafer starts. Now that’s the beginning of the production line, right? It does take a number of quarters before those wafer starts or a number of months before those wafer starts transition into products and ship to customers. And a typical time from a wafer start to like a transceiver shipment is about 6 months.
But that’s a great leading indicator on our indium phosphide ramp. And we’re already seeing the benefits this quarter from the initial production that started in our September quarter of last year. So I’m really pleased with that ramp. And again, the reason we’re so focused on that is because 6-inch wafer versus a 3-inch wafer is more than 4x as many chips at less than half the cost. And so we’re really pleased with that ramp. And then Samik, it sounded like you had a follow-up?