Cover Page - shares	3 Months Ended
	Mar. 31, 2021	Apr. 23, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-35061
Entity Registrant Name	NeoPhotonics Corp
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3253730
Entity Address, Address Line One	3081 Zanker Road
Entity Address, City or Town	San Jose
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	95134
City Area Code	408
Local Phone Number	232-9200
Title of 12(b) Security	Common Stock, $0.0025 par value
Trading Symbol	NPTN
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		51,329,729
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001227025
Current Fiscal Year End Date	--12-31