Hyuk-Choon Kwon

1.25-Gb/s Wavelength-Division Multiplexed Single-Wavelength Colorless Radio-on-Fiber Systems Using Reflective Semiconductor Optical Amplifier

A wavelength-division multiplexed colorless radio-on-fiber (RoF) system based on a reflective semiconductor optical amplifier (RSOA) is proposed in this paper. This scheme has a colorless and simple base station (BS), because an RSOA playing the role of amplification and modulation is used at the BS, irrespective of the wavelength. The spurious-free dynamic range, gain, and noise figure of both the downlink and uplink are presented to verify the suitability of the scheme for an RoF system. Error-free transmissions for both uplink and downlink wireless signals of 1.25 Gb/s are demonstrated. From the experimental results using an RF subcarrier of 3 GHz as a wireless signal, it is held that the performance of this scheme will change only slightly when using a millimeter-wave signal (> 30 GHz).

A self-seeded reflective SOA-based optical network unit for optical beat interference robust WDM/SCM-PON link

We have proposed and experimentally demonstrated a novel optical source configuration that uses a self-seeded reflective semiconductor optical amplifier (RSOA) as an optical network unit (ONU) in a wavelength division multiplexed/subcarrier multiplexing (SCM)-passive optical network (PON). A fiber Bragg grating (FBG) was used to obtain a single longitudinal mode of the RSOA. The proposed ONU configuration is simple, cost-effective, and effective regardless of wavelength allocation. Additionally, it would be robust for optical beat interference (OBI) noise. As the ONU is composed only of an RSOA and FBG, the self-seeded RSOA, due to the strong self-injection caused by the reflection of the FBG, has a broad optical spectrum. A self-homodyne apparatus method was performed in order to demonstrate the robustness of the self-seeded RSOA in OBI. To confirm the validity of the proposed scheme, a 16-quadrature amplitude modulation transmission experiment was performed in a 10-, 20-km optical access link with an SCM frequency of 1 GHz. An error vector magnitude of less than 4% for 2 Msps was successfully obtained through the transmission experiment

Linearization of RoF Optical Source by using Light-injected Gain Modulation

We presented a novel scheme for linearization of optical source in radio-over-fiber system. The linearization scheme consists of RF attenuator, RF phase shifter, and a different light source for the purpose of reducing the third order intermodulation products (IMD3). We experimentally demonstrated two tone SCM optical links where linearization scheme was applied. With optimizing the phase amount and IMD3 intensity from a different LD source, we obtained optimal condition, which results in reducing carrier to IMD3 ratio of 30dBc.

Bidirectional SCM Transmission Using a Noise-Suppressed Fabry–Pérot Laser Diode and a Reflective Semiconductor Optical Amplifier in a WDM/SCM-PON Link

We have proposed and experimentally demonstrated a bidirectional hybrid wavelength-division-multiplexed/subcarrier-multiplexed (SCM)-passive optical network based on a noise-suppressed Fabry-Peacuterot laser diode (FP-LD) and a reflective semiconductor optical amplifier (RSOA). For downlink data transmission, an FP-LD with multiple wavelength characteristics was used, and the mode partition noise of the FP-LD was reduced using a gain-saturated SOA with high-pass filter characteristics. For uplink data transmission, the downlink optical source was reused and remodulated by an SCM method, using an RSOA. A bidirectional SCM link with radio frequencies (RFs) of 2.4 GHz in the downlink and 1.0 GHz in the uplink was implemented. To confirm the validity of the proposed configuration, a 16-quadrature amplitude modulation transmission experiment was performed on a 10-km bidirectional optical access link. The transmission performance was investigated by means of the error vector magnitude and RF spectrum

Noise suppressed Fabry-Pe/spl acute/rot laser diode with gain-saturated semiconductor optical amplifier for hybrid WDM/SCM-PON link

We have proposed and experimentally demonstrated a novel optical source configuration for hybrid wavelength-division-multiplexing/subcarrier multiplexing (SCM) passive optical network using a gain-saturated semiconductor optical amplifier (GS-SOA) and a Fabry-Peacuterot laser diode (F-P LD). The mode partition noise of an F-P LD was suppressed by the frequency response characteristic of a GS-SOA. To confirm the validity of the proposed scheme, 16-quadrature amplitude modulation transmission experiment was performed in 20.4-km optical access link for three SCM frequency groups (0.8, 1.5, and 2.4 GHz). The error vector magnitude less than 4% was successfully obtained in the transmission experiment

Performance analysis of a wavelength-locked Fabry-Perot laser diode by light injection of an external spectrally sliced Fabry-Perot laser diode

We have analyzed and experimentally demonstrated the performance of a wavelength-locked Fabry-Perot laser diode (FP-LD) with a spectrally sliced FP-LD as an external-injection optical source. A high side-mode suppression ratio exceeding 30 dB was obtained, and the noise characteristic of the wavelength-locked FP-LD was analyzed in terms of both mode partition noise and interferometric noise. The measured relative intensity noise had a minimum value of -140 dB/Hz. We also investigated the transmission characteristics such as the Q factor and extinction ratio for a 622 Mbits/s and 2.5 Gbits/s baseband digital signal.

WDM Passive Optical Network with Simultaneous Wireline/Wireless Downlink Transmission and Wavelength Reuse for Uplink Connection

WDM passive optical network with a simultaneous wireline/wireless data transmission in downlink and a wavelength reuse using a reflective semiconductor optical amplifier (RSOA) in uplink was proposed and experimentally demonstrated. This proposed scheme uses a Mach-Zehnder modulator (MZM) in the central office (CO) and a RSOA in the optical network unit (ONU). We verified the feasibility of the proposed scheme through 1.25-Gbps bidirectional transmission experiment.

WDM-PON with Broadcasting Function Using Direct ASE Modulation of Reflective SOA

We have proposed and experimentally investigated a novel cost effective WDM-PON system which broadcasts the direct modulated ASE of RSOA for broadcasting signal and re-modulates the broadcasted ASE of RSOA for up-link at the ONU.

Optical Beat Noise Reduction Using FM to AM Conversion of Injection-Locked FP-Laser Diode in Reflective SOA Based WDM/SCM-Passive Optical Networks

A new scheme for reducing optical beat interference noise in a reflective semiconductor optical amplifier based wavelength division multiplexed/subcarrier multiplexing - passive optical network is proposed. This method uses an Fabry Perot laser locked by modulated lights from optical network units in a central office. As an experimental verification, it is reported that carrier to noise ratio is enhanced by 10 dB and power penalty is improved by 16 dB.

Optical network unit based on self-seeded reflective semiconductor optical amplifier for WDM-PON

A novel Optical network unit based on self-seeded RSOA for WDM-PON was proposed. The RSOA was self-seeded by amplified spontaneous emission of itself using fiber Bragg grating (FBG) without additional optical source.