dygraph: increase size of axis tick marks with axisLabelFormatter

Question

I made some figures with dygraph and I'm happy with them but since I put them side by side in my latex / pdf, the size of the axis tick marks (the numbers at y axis, and some months at x axis: Jan 2017 Apr 2017 Jul 2017) are to small. I simply want to increase them and don't succeed...I could put them apart with pixelsPerLabel= 100, so there would be place for bigger letters, but I can't use axisLabelFormatter

here is my function

dygraph_dfm2 <- function(xts_object, show = "never", impulse = "2016-04-01", legend_compl = "", last_data = last_data_point , title = "some title"){
  dygraph(xts_object,main = title)%>%
    dyOptions(digitsAfterDecimal = 3,drawAxesAtZero = TRUE) %>%     # dyOptions(dygraph,digitsAfterDecimal = 5) ... dygraph fills the graph!
      # dyAxis("y", label = "AAA", axisLabelWidth = 34) %>%
      # dyAxis("x", label = "AAA",axisLabelWidth = 34) %>%
      # dyAxis("x", label = "xxx") %>%
dySeries(colnames(xts_object)[1], strokePattern = "solid", strokeWidth = 2, color = "blue")%>%
dyEvent(last_data, paste(last_data_point), labelLoc = "bottom")%>%
dyLegend(show = show) %>%
dyShading(from = "1960-04-01", to = "1961-02-01") %>%
dyShading(from = "1969-12-01", to = "1970-11-01") %>%
dyShading(from = "1973-11-01", to = "1975-03-01")%>%
dyShading(from = "1980-01-01", to = "1980-07-01")%>%
dyShading(from = "1981-07-01", to = "1982-11-01")%>%
dyShading(from = "1990-07-01", to = "1991-03-01")%>%
dyShading(from = "2001-03-01", to = "2001-11-01")%>%
dyShading(from = "2007-12-01", to = "2009-06-01")
}

How can I increase them to 1.5 size etc? Thanks!