Shinya Sudo

Full C-band external cavity wavelength tunable laser using a liquid-Crystal-based tunable mirror

A compact full C-band external cavity wavelength tunable laser is proposed. The cavity contains a fixed etalon and makes use of a liquid-crystal-based tunable mirror. The measurement results show a tuning range of 35 nm with fiber coupled power of more than 15 dBm. The sidemode suppression ratio is higher than 50 dB over the whole range and the relative intensity noise is below -148 dB/Hz. The linewidth is in worst case 700 kHz.

Wavelength-selectable microarray light sources for S-, C-, and L-band WDM systems

We report on the first demonstrated near-complete coverage of the S-, C-, and L-bands using six different ranges of wavelength-selectable microarray light sources (WSLs) based on a distributed-feedback (DFB) laser diode (LD) array. The six devices were fabricated on only two wafers. Each device has a tuning range of more than 15 nm, a sidemode suppression ratio of over 40 dB, and a fiber-coupled power greater than around 10 mW.

Growth pressure dependence of neighboring mask interference in densely arrayed narrow-stripe selective MOVPE for integrated photonic devices

We have investigated the dependence of neighboring mask interference on growth pressure in narrow-stripe selective MOVPE with arrayed stripe masks for the growth of densely-arrayed optical waveguides. Atmospheric-pressure MOVPE is effective in fabricating densely arrayed waveguide without inducing neighboring mask interference. On the other hand, low-pressure MOVPE has the advantage that the distribution of PL-wavelength over the microarray waveguide can easily be controlled by utilizing neighboring mask interference. An appropriate mask pattern and growth conditions for fabricating integrated photonic devices can thus be selected. A mask interference constant was introduced and used to simulate distributions of PL-wavelengths in arrayed waveguide. Simulated results matched experimental results well.

Wavelength-selectable light sources fabricated using advanced microarray-selective epitaxy

An advanced microarray-selective epitaxy with wider open-stripes has been developed for simple fabrication of distributed-feedback laser diode array-based high-power wavelength-selectable light sources. More than 40-mW fiber-coupled power and 50-dB sidemode suppression ratio over 9.2-nm wavelength were achieved.

First demonstration of novel active multi-mode interferometer (MMI) LDs integrated with 1st order-mode permitted waveguides

Here we propose novel active multi-mode-interferometer (MMI) laser diodes (LDs) for 14XXnm fiber amplifier pump applications. The waveguide of the LDs is consisted from 1x1-MMI couplers integrated with 1st order-mode permitted waveguides to enhance the total active area. Although there is no single-mode waveguide region inside the cavity, the novel active MMI-LDs emitted in stable single-transverse-mode output up to maximum output power. Moreover, they achieved high output power of 1.46W, and low driving voltage of only 1.75V at 1W output power.

Wavelength channel accuracy of an external cavity wavelength tunable laser with intracavity wavelength reference etalon

A theoretical and experimental study of the wavelength channel accuracy of an external cavity wavelength tunable laser (ECTL) with a wavelength reference etalon inside the laser cavity is presented. A feedback control scheme for wavelength locking is proposed based on monitoring of the forward output power. The cavity parameters with an impact on the channel accuracy, using the proposed scheme, are indicated, and guidelines toward optimization of the etalon are proposed. Experimental demonstration of a channel accuracy of less than 0.6 GHz for a full C-band ECTL with a channel spacing of 50 GHz confirms the high potential of this laser configuration

10-Gb/s 23-km penalty-free operation of 1310-nm uncooled EML with semi-insulating BH structure

We have developed a 1310-nm uncooled electroabsorption modulator integrated light source (EML) with an AlGaInAs multiple quantum well (MQW) active/absorption stripe, which was simultaneously grown using the narrow-stripe selective MOVPE technique and was buried with an Fe-doped InP. The Al-content MQW oxidation was effectively inhibited by using the same technique. An experiment-based evaluation of the devices performance revealed that by only changing the modulation bias voltage linearly with temperature, it was possible to achieve 10-Gb/s penalty-free operation at up to 85/spl deg/C over a 23-km single-mode fiber.

Transmission Over 360 km Using a 2.5-Gb/s SOA-Modulator Integrated Full

We present an external-cavity wavelength-tunable laser with a semiconductor optical amplifier-modulator monolithically integrated on the gain chip. The modulator chirp is analyzed, and it is explained how the chirp can be partially cancelled by self-phase modulation in the transmission fiber. Full C-band transmission of 2.5-Gb/s data over 360 km is demonstrated with small power penalty

C

Integration of a booster semiconductor optical amplifier (SOA) is an efficient way of overcoming losses in InP based Mach-Zehnder modulators. We analyze the impact of locating the SOA before and after the MZM, respectively, in terms of output power and signal integrity at 10 Gb/s, both experimentally and theoretically. For a device with 10 dB MZM loss it is found that, for a fixed power consumption, locating the SOA after the MZM provides 7-9 dB higher output power. This advantage is reduced for lower MZM losses but remains significant. With the SOA after the MZM, the gain is restricted by dynamic saturation effects (waveform distortion), which is not the case if the SOA is at the input of the MZM. The waveform distortion is accompanied by a spectral red-shift, which degrades the transmission performance. Simulations show that for MZM losses below ~4 dB, locating the SOA before the MZM can provide a higher power with no waveform distortion and negative chirp, at the cost of a higher SOA gain. For higher MZM losses it is unfeasible to locate the SOA before the MZM, due to a prohibitively large power consumption.

-Band Wavelength-Tunable Transmitter

In this paper, high-performance full-band external cavity wavelength-tunable lasers (ECTLs) are detailed. Our approach utilizes an external cavity configuration, which makes use of a liquid-crystal tunable mirror and a wavelength reference etalon. This ECTL module shows a tuning range of 45 nm, fiber-coupled output power of more than 14 dBm with a side-mode suppression ratio better than 59 dB, wavelength accuracy of 0.6 GHz, relative intensity noise better than -150 dB/Hz, and linewidth narrower than 1 MHz.