The deployment rate of wavelength division multiplexed passive optical
networks (WDM-PONs) is expected to accelerate with the availability
of cost-efficient wavelength-specific transmitters. Fueled by this
promise, we propose and experimentally demonstrate a novel scheme
that facilitates the use of reflective semiconductor optical amplifiers
(RSOAs) as colorless upstream transmitters. Central to the scheme
is the use of a passive reflective path that is placed at the remote
node (RN) to reflect a spectral slice of the broadband amplified
spontaneous emission (ASE) light emitted from each RSOA. The reflected
spectral slice, termed as a seeding light, establishes a self-seeding
of the RSOA with measurements indicating the self-seeded output to
be incoherent with a low relative intensity noise. The subsequent
direct modulation of the self-seeding RSOA with nonreturn-to-zero
data at 1.25 Gb/s for upstream transmission exhibits good transmission
and crosstalk performance after traversing 21 km of single-mode fiber.
Our proposed scheme eliminates the need for centralized broadband
sources, external modulators, and active temperature control within
the RN and between the RN and the optical network unit. Aside from
the feasibility study of self-seeding RSOAs, we investigate the upstream
performance dependence on the characteristics of the seeding light.
Our investigations reveal that there exists a noise floor limit of
the bit error rate (BER) of the self-seeded upstream signal. The
noise floor is shown to vary with an initial optical seeding power
that affects the level of ASE noise suppression of the self-seeded
upstream signal. None the less, the RSOA self-seeds at a user-defined
wavelength with a sufficient suppression of ASE noise to achieve
a BER=10-9 with only -30.5 dBm of initial optical seeding power.
Our characterization of the frequency response of the RSOA reveals
a high-pass filter response that suppresses the modulation on the
reflected seeding ligh- t, and thus stabilizing the self-seeded output.
Collectively, these features highlight the potential of using the
self-seeding RSOAs to realize a cost-efficient WDM-PON solution in
the near future