Abstract

Wavelength control and cost reduction important issues for wavelength-division multiplexed (WDM) transmitters. We investigate an innovative WDM transmitter that can solve the above problems. Figure 1 shows the design of the WDM transmitter. The long wavelength (1.3/1.55 μm) laser has a vertical-cavity surface-emitting (VCSEL) structure where a micromachined tunable curved mirror is incorporated into the device for wavelength tuning. The output light from the VCSEL is tapped and fed into a wavelength tunable photodetector. The photodetector has an intracavity resonant structure where its resonant wavelength is determined by the position of the mi- cromachined top mirror. By altering the resonant wavelength, the detector functions as a spectrometer that can monitor the emission wavelength of the VCSEL in real time. The error signal for the wavelength, contained in the photocurrent of the detector, is fed back to the tunable VCSEL for wavelength adjustment; hence a closed-loop wavelength control system is formed.

© 1996 Optical Society of America