Operating Segments and Geographic Information - Information on Reportable Segments (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 01, 2022 USD ($)	Jan. 02, 2021 USD ($)	Jan. 01, 2022 USD ($) segment	Jan. 02, 2021 USD ($)
Information on reportable segments
Number of broad business categories (in segment) | segment			2
Total net revenue	$ 314.8	$ 299.9	$ 641.6	$ 584.6
Gross profit	$ 190.5	$ 180.1	$ 385.5	$ 349.5
Gross margin (as a percent)	60.50%	60.10%	60.10%	59.80%
Operating income	$ 49.3	$ 42.3	$ 96.2	$ 73.6
Operating margin (as a percent)	15.70%	14.10%	15.00%	12.60%
Other Items
Information on reportable segments
Total net revenue	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Gross profit	(8.6)	(9.2)	(18.1)	(18.6)
Operating income	(24.0)	(24.5)	(51.4)	(53.8)
Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	244.2	206.7	472.1	390.2
Gross profit	$ 159.4	$ 130.9	$ 306.8	$ 248.7
Gross margin (as a percent)	65.30%	63.30%	65.00%	63.70%
Operating income	$ 45.6	$ 22.2	$ 76.3	$ 35.5
Operating margin (as a percent)	18.70%	10.70%	16.20%	9.10%
Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	$ 214.4	$ 180.9	$ 419.3	$ 343.0
Gross profit	$ 138.0	$ 113.3	$ 270.7	$ 216.8
Gross margin (as a percent)	64.40%	62.60%	64.60%	63.20%
Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	$ 29.8	$ 25.8	$ 52.8	$ 47.2
Gross profit	$ 21.4	$ 17.6	$ 36.1	$ 31.9
Gross margin (as a percent)	71.80%	68.20%	68.40%	67.60%
Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	$ 70.6	$ 93.2	$ 169.5	$ 194.4
Gross profit	$ 39.7	$ 58.4	$ 96.8	$ 119.4
Gross margin (as a percent)	56.20%	62.70%	57.10%	61.40%
Operating income	$ 27.7	$ 44.6	$ 71.3	$ 91.9
Operating margin (as a percent)	39.20%	47.90%	42.10%	47.30%
Product revenue
Information on reportable segments
Total net revenue	$ 277.4	$ 262.1	$ 566.5	$ 510.0
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	206.8	169.3	397.3	316.2
Product revenue | Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	189.6	156.4	369.2	295.6
Product revenue | Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	17.2	12.9	28.1	20.6
Product revenue | Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	70.6	92.8	169.2	193.8
Service revenue
Information on reportable segments
Total net revenue	37.4	37.8	75.1	74.6
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	37.4	37.4	74.8	74.0
Service revenue | Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	24.8	24.5	50.1	47.4
Service revenue | Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	12.6	12.9	24.7	26.6
Service revenue | Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	$ 0.0	$ 0.4	$ 0.3	$ 0.6