parsing text-files in powershell with where and select-string operators - optimization

Question

recently I had to solve a problem reading a large amount of logfiles and picking specific chunks of text out of them.
With some trial and error I found a working solution but I'd like to know if there are better approaches.
These logfiles contain text-blocks, each is introduced by a 'heading' followed by an unknown amount of entries and finished with an empty line. (Example below, the numbers are pseudo linenumbers)
35# logevent1
36# entry1
37# entry2
38# entry3
39#
40# logevent2
41# entry1
42# entry2
Thus I know the 'logevent'-tag I can retrieve the line with $line = $logfile | Select-String -Pattern 'logevent1' and with $lineNumber = $line | Select-Object -ExpandProperty LineNumber I have the first value to use Get-Content with range operator [$x..$y].
In my example this would be 35. But how do I get the first empty line behind the text block?
I tried to work with Select-String -Pattern '' but that gives an instant exception due to the string is empty. So I wrote he following function:
function Get-TextBlock([string]$filePath,$lineNumber)
{
$startLine = ($lineNumber -1)
$counter = 0
$emptyLines = #()
Get-Content (Get-ChildItem $filePath) | ForEach-Object {
if( $_ -eq '' ) {
$emptyLines += $counter;
}
$counter++
}
$endLine = 0
$counter = 0
while( $endLine -le $startLine) {
$endLine = ($emptyLines[$counter]); $counter++;
}
$output += ((Get-ChildItem $filePath) | Get-Content)[$startLine..$endLine]
return $output
}
As mentioned before the function works for me but I feel like there are much better and easier ways to perfrom this task.
The Output (after removing my pseudo-line-numbers ;) ) looks like this
PS F:\scripts\powershell> Get-TextBlock '.\function-test.txt' 35
logevent1
entry1
entry2
entry3
____________________________________________________________________________
Kind regards