Operating Segments and Geographic Information - Information on Reportable Segments (Details) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 03, 2021 USD ($)	Mar. 28, 2020 USD ($)	Apr. 03, 2021 USD ($) segment	Mar. 28, 2020 USD ($)
Information on reportable segments
Number of broad business categories (in segment) | segment			2
Total net revenue	$ 303.4	$ 256.2	$ 888.0	$ 869.7
Gross profit	$ 182.0	$ 146.8	$ 531.5	$ 510.7
Gross margin (as a percent)	60.00%	57.30%	59.90%	58.70%
Operating income	$ 35.9	$ 9.1	$ 109.5	$ 74.8
Operating margin (as a percent)	11.80%	3.60%	12.30%	8.60%
Other Items
Information on reportable segments
Total net revenue	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Gross profit	(9.4)	(9.9)	(28.0)	(29.1)
Operating income	(25.5)	(28.9)	(79.3)	(83.8)
Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	211.2	187.0	601.4	641.0
Gross profit	$ 135.5	$ 120.3	$ 384.2	$ 416.5
Gross margin (as a percent)	64.20%	64.30%	63.90%	65.00%
Operating income	$ 20.9	$ 13.8	$ 56.4	$ 73.6
Operating margin (as a percent)	9.90%	7.40%	9.40%	11.50%
Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	$ 190.9	$ 163.9	$ 533.9	$ 565.8
Gross profit	$ 123.1	$ 104.3	$ 339.9	$ 367.1
Gross margin (as a percent)	64.50%	63.60%	63.70%	64.90%
Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	$ 20.3	$ 23.1	$ 67.5	$ 75.2
Gross profit	$ 12.4	$ 16.0	$ 44.3	$ 49.4
Gross margin (as a percent)	61.10%	69.30%	65.60%	65.70%
Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	$ 92.2	$ 69.2	$ 286.6	$ 228.7
Gross profit	$ 55.9	$ 36.4	$ 175.3	$ 123.3
Gross margin (as a percent)	60.60%	52.60%	61.20%	53.90%
Operating income	$ 40.5	$ 24.2	$ 132.4	$ 85.0
Operating margin (as a percent)	43.90%	35.00%	46.20%	37.20%
Product revenue
Information on reportable segments
Total net revenue	$ 266.6	$ 223.8	$ 776.6	$ 770.5
Product revenue | Other Items
Information on reportable segments
Total net revenue	0.0	0.0	0.0	0.0
Product revenue | Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	174.4	154.6	490.6	542.1
Product revenue | Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	166.5	146.0	462.1	507.2
Product revenue | Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	7.9	8.6	28.5	34.9
Product revenue | Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	92.2	69.2	286.0	228.4
Service revenue
Information on reportable segments
Total net revenue	36.8	32.4	111.4	99.2
Service revenue | Other Items
Information on reportable segments
Total net revenue	0.0	0.0	0.0	0.0
Service revenue | Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	36.8	32.4	110.8	98.9
Service revenue | Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	24.4	17.9	71.8	58.6
Service revenue | Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	12.4	14.5	39.0	40.3
Service revenue | Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	$ 0.0	$ 0.0	$ 0.6	$ 0.3