Operating Segments and Geographic Information - Information on Reportable Segments (Details) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 28, 2024 USD ($)	Dec. 30, 2023 USD ($)	Dec. 28, 2024 USD ($) segment	Dec. 30, 2023 USD ($)
Information on reportable segments
Number of broad business categories (in segment) | segment			2
Total net revenue	$ 270.8	$ 254.5	$ 509.0	$ 502.4
Gross profit	$ 160.8	$ 148.0	$ 296.9	$ 292.4
Gross margin (as a percent)	59.40%	58.20%	58.30%	58.20%
Operating Income (Loss)	$ 22.2	$ 22.4	$ 33.7	$ 38.4
Operating margin (as a percent)	8.20%	8.80%	6.60%	7.60%
Segment Measures
Information on reportable segments
Gross profit	$ 165.4	$ 152.8	$ 306.1	$ 301.8
Operating Income (Loss)	40.4	33.7	64.3	64.5
Other Items
Information on reportable segments
Total net revenue	0.0	0.0	0.0	0.0
Gross profit	(4.6)	(4.8)	(9.2)	(9.4)
Operating Income (Loss)	(18.2)	(11.3)	(30.6)	(26.1)
Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	199.9	179.6	359.3	350.0
Gross profit	$ 129.5	$ 113.8	$ 226.6	$ 222.1
Gross margin (as a percent)	64.80%	63.40%	63.10%	63.50%
Operating Income (Loss)	$ 17.4	$ 6.4	$ 10.1	$ 7.9
Operating margin (as a percent)	8.70%	3.60%	2.80%	2.30%
Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	$ 179.0	$ 155.5	$ 320.6	$ 305.5
Gross profit	$ 115.4	$ 97.2	$ 201.7	$ 191.8
Gross margin (as a percent)	64.50%	62.50%	62.90%	62.80%
Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	$ 20.9	$ 24.1	$ 38.7	$ 44.5
Gross profit	$ 14.1	$ 16.6	$ 24.9	$ 30.3
Gross margin (as a percent)	67.50%	68.90%	64.30%	68.10%
Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	$ 70.9	$ 74.9	$ 149.7	$ 152.4
Gross profit	$ 35.9	$ 39.0	$ 79.5	$ 79.7
Gross margin (as a percent)	50.60%	52.10%	53.10%	52.30%
Operating Income (Loss)	$ 23.0	$ 27.3	$ 54.2	$ 56.6
Operating margin (as a percent)	32.40%	36.40%	36.20%	37.10%
Product revenue
Information on reportable segments
Total net revenue	$ 225.7	$ 210.9	$ 423.2	$ 416.5
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	154.8	136.0	273.5	264.1
Product revenue | Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	146.9	125.2	259.5	245.6
Product revenue | Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	7.9	10.8	14.0	18.5
Product revenue | Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	70.9	74.9	149.7	152.4
Service revenue
Information on reportable segments
Total net revenue	45.1	43.6	85.8	85.9
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	45.1	43.6	85.8	85.9
Service revenue | Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	32.1	30.3	61.1	59.9
Service revenue | Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	13.0	13.3	24.7	26.0
Service revenue | Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	$ 0.0	$ 0.0	$ 0.0	$ 0.0