Retrieve a repeating person’s name in array of string

Everyone!
I’m currently working on the project where I should merge some pdf files into one using Laravel.
I receive response from Airtable response.
The main thing is that after merging pdf files I’m gonna set a name of merged pdf file.
For example, I have to merge these files:

0:"D:DevelopmentsAirtablePDFCombinerairtable-pdf-combinerstorageapp/pdf_filesSalvageQuoteSummaryreportChristenPretrick.pdf"
1:"D:DevelopmentsAirtablePDFCombinerairtable-pdf-combinerstorageapp/pdf_filesSummaryReportChristenPretrick.pdf"
2:"D:DevelopmentsAirtablePDFCombinerairtable-pdf-combinerstorageapp/pdf_filesEstimateChristenPretrick.pdf"
3:"D:DevelopmentsAirtablePDFCombinerairtable-pdf-combinerstorageapp/pdf_filesPhotoSheetChristenPretrick.pdf"
4:"D:DevelopmentsAirtablePDFCombinerairtable-pdf-combinerstorageapp/pdf_filesComp26700.00.pdf"
5:"D:DevelopmentsAirtablePDFCombinerairtable-pdf-combinerstorageapp/pdf_filesComp26888.00.pdf"
6:"D:DevelopmentsAirtablePDFCombinerairtable-pdf-combinerstorageapp/pdf_filesComp27991.00.pdf"
7:"D:DevelopmentsAirtablePDFCombinerairtable-pdf-combinerstorageapp/pdf_filesNADA.pdf"

As you see, in first three files there is a name of person: “ChristenPretrick”, which should be a name of the merged pdf file.

But how to get only this name in this array using the Laravel Controller.
Please leave me feedback, will be extremely appreciated to your answer.
Best Regards.