  Black widows (BWs) are a type of eclipsing millisecond pulsars (MSPs) with
low companion masses ($\lesssim0.05\,\rm M_\odot$) and tight orbits ($<1\,$d).
PSR J1953+1844 is a BW with the shortest orbital period ($\sim53$ minutes) ever
discovered, which was recently detected by Five-hundred-meter Aperture
Spherical radio Telescope. Its companion mass is $\sim0.01\,\rm M_\odot$
according to its mass function, indicating that the companion may be a
hydrogen-deficient star. However, the origin of PSR J1953+1844 is highly
unclear. In this paper, we explored the origin of PSR J1953+1844 through the
neutron star+He star channel, in which the system can experience ultracompact
X-ray binary phase. We found that the He star donor channel can reproduce the
characteristics of PSR J1953+1844, indicating that this work provides an
alternative formation channel for this source. Meanwhile, the minimum orbital
period of BWs formed by this channel is $\sim28$ minutes, corresponding to the
companion mass of $0.058\,\rm M_\odot$. In addition, we note that even though
PSR J1953+1844 has a short orbital period, it cannot be detected by the
gravitational wave (GW) observatories like Laser Interferometer Space Antenna,
TaiJi and TianQin. However, we still expect that the BWs with extremely tight
orbit produced by this channel are the potential sources of future space-based
GW observatories. Moreover, our simulations show that PSR J1953+1844 may
eventually evolve into an isolated MSP.
