  We demonstrate a Hong-Ou-Mandel interference between two independent,
intrinsically pure, heralded single photons from spontaneous parametric down
conversion (SPDC) at telecom wavelength. A visibility of $85.5\pm8.3%$ was
achieved without using any bandpass filter. Thanks to the
group-velocity-matched SPDC and superconducting nanowire single photon
detectors (SNSPDs), the 4-fold coincidence counts are one order higher than
that in the previous experiments. The combination of bright single photon
sources and SNSPDs is a crucial step for future practical quantum
info-communication systems at telecom wavelength.
