Figuring out IR sensor PWM frequency with Arduino
You mistakenly believe that the carrier frequency of 38 kHz should be available at the data output pin of the infrared detector chip. These chips provide a logic output indicating the presence of 38 kHz. Most are frequency-selective, being more sensitive at one frequency somewhere between 35 kHz - 60 kHz.
A data sheet pulled at random specifies typical pulse bursts that might be used to encode digital data (pulse burst timing highlighted in red):

In your case, \$f_o\$ might be close to 38 kHz. No fewer than six cycles \$t_{pi}\$ are recommended for the length of one baud. Perhaps your transmitter includes a few more cycles (ten or eleven?) to be safe. The receiver circuitry requires about five cycles before commit, \$t_d\$. Hopefully, a similar delay at end-of-pulse occurs, but the graph at right suggests the end-of-pulse extends a little longer than \$t_d\$. However, pulse width is impressively constant over five magnitudes of infrared intensity.
Note that the presence of a burst of 38 kHz from the transmitter most often sends the output of the receiver to a logic low. No optical signal yields a logic high at receiver output, sometimes with a fast false-detect glitch (which should be rejected if its length is short). A large-value pull-up resistor added between output pin and Vdd may be required to ensure that an idle receiver goes to logic high.
You will still have to determine how these pulse bursts are encoded into logical bits. Many protocols exist, some use pulse position, others use pulse length encoding.