​

​

March 31, 

​

December 31, 

​

​

2026

​

2025

​

​

(in thousands)

Convertible Debt

​

​

​

​

​

​

​

​

​

​

​

​

​

2029 Convertible Notes

​

$

345,000

​

$

345,000

​

​

​

​

​

​

​

Term Loan

​

​

​

​

​

​

​

​

​

​

​

​

​

Wells Fargo Term Loan due June 2028

​

​

250,000

​

​

250,000

​

​

​

​

​

​

​

Other Loans and Payment Obligations

​

​

​

​

​

​

​

​

​

​

​

​

​

French government loans due December 2026

​

​

57

​

​

56

​

​

​

​

​

​

​

Line of Credit Facilities

  ​ ​ ​

​

​

  ​ ​ ​

​

  ​ ​ ​

​

​

​

​

​

​

​

Line of credit facility with China Merchant Bank due October 2026

​

​

—

​

​

—

Wells Fargo Revolving line of credit facility due June 2028

​

​

—

​

​

—

Line of credit facility with ICBC Bank due November 2033

​

​

25,052

​

​

24,649

​

​

​

​

​

​

​

Equipment under Finance Leases

​

232

​

264

Total debt

​

620,341

​

619,969

Less: current portion of long-term debt

​

1,671

​

1,641

Less: loan issuance costs

​

​

8,869

​

​

9,579

Long-term debt, net of current portion and unamortized debt issuance costs

​

$

609,801

​

$

608,749