K. Nakatsuhara

All-optical set-reset operation in a distributed feedback GaInAsP waveguide

An optical bistable device is realized by an optical feedback structure and the optical Kerr effect. We fabricated an optical distributed feedback waveguide in a GaInAsP-InP wafer. All-optical set-reset operation has been observed in the GaInAsP-InP waveguide at a wavelength of 1.56 /spl mu/m.

All-optical switching in a distributed-feedback GaInAsP waveguide.

The characteristics of all-optical switching in a waveguide device with a distributed-feedback structure were experimentally investigated. The device was composed of a strip-loaded GaInAsP/InP waveguide and a distributed-feedback structure, which was fabricated by a combination of reactive-ion etching and electron-beam exposure. In the experiments, several optical switching operations were demonstrated. In particular, the all-optical set-reset operation and threshold operation were obtained.

GaInAsP-InP distributed feedback waveguides for all-optical switching

All-optical switching characteristics of waveguide devices having a nonlinear distributed feedback structure are reported theoretically and experimentally. These devices were composed of a strip-loaded GaInAsP-InP waveguide and a Bragg reflector, which were suitable for optical integrated circuit. In the experiments, all-optical and gate operation and set-reset operation for two output ports were successfully demonstrated.

Weighted distributed feedback structure for all-optical bistable devices.

We proposed to use a distributed feedback structure with a weighted coupling coefficient (W-DPB) in an all-optical bistable device in order to improve on-state transmittance and to reduce threshold intensity. Through numerical calculations, characteristics of the W-DPB structure were discussed compared with those of a conventional DPB structure. The W-DPB optical bistable device exhibits high on-state transmittance and low-threshold input intensity. Fabrication of the W-DPB structure with a periodicity of 169.8 nm is demonstrated on a CdS(x)Se(1-x)-doped glass substrate by means of holographic exposure with a double-coated photoresist and reactive ion etching in CHP(3).

Dependence of Threshold Switching Power on the Control-Light Wavelength in a Nonlinear Distributed-Feedback GaInAsP Waveguide.

We demonstrate all-optical bistable switching by using orthogonally and parallelly polarized control light in a nonlinear distributed feedback GaInAsP waveguide. When the control light that is orthogonally polarized to the signal light is within its stopband, it is possible to extract the signal without using any external devices. Also, we investigate theoretically and experimentally the dependence of threshold switching power on the wavelength and polarization of control light.

Demonstration of all-optical AND gate operation in a GaInAsP waveguide

In the present paper an all-optical AND gate operation in a nonlinear DFB waveguide monolithically integrated with a Y-coupler is reported. It is concluded that the device does exhibit optical AND gate operation due to the intensity-dependent nonlinearity.

Dependence of control light wavelength in all-optical switching of nonlinear strip-loaded distributed feedback waveguide

In this paper, all-optical switching operation using orthogonally and parallelly polarized control light for TE-polarized signal is experimentally investigated in the strip-loaded distributed feedback waveguide. In addition, the relation between threshold switching power and control light wavelength is investigated.

Demonstration of all-optical switching in a GaInAsP distributed feedback waveguide

All-optical threshold operation and set-reset operation are successfully demonstrated in a GaInAsP waveguide with a Bragg reflector. In order to integrate the bistable device with other optical functional devices, it is the most promising way to use distributed Bragg reflectors for optical feedback. An intensity-dependent Bragg condition derives all-optical switching in a Bragg reflector-loaded waveguide having an intensity-dependent refractive index.

Waveguide optical bistable devices with weighted distributed feedback structure

the laser. Two techniques have been used to scan the phase. In Fig. 2, the external cavity length was changed by moving the mirror M with a piezoelectric ceramic. The mirror is moved between one position where only the natural mode A is stable and another one where the orthogonally polarized mode B is also stable. In Fig. 3, the current of the VCSEL was modulated by applying a small sinusoidal voltage at 50 MHz. We interpret this as causing a laser frequency chirp and a change in phase of the feedback. Polarization flips were seen at modulation frequencies up to 200 MHz with a characteristic time less than 1 ns. (Note that the spikes on the signal in Fig. 3 are artifacts of the sampling rate of the digital scope used.) In summary, polarization flips have been observed in a VCSEL. The bistability is controlled by the phase of the feedback. *Dept. of Physics, University of Toronto, Toronto, Ontario, Canada M5S 1A7 **ATBT Bell Labs, Murray Hill, New Jersey, USA 1. A. D. May, G. Stephan, J.0.S.A.B 6 (12), 2355 (1989). 2. P. Paddon, E. Sjewe, A. D. May, M. Bourouis, G. Stephan, J.0.S.A.B 4 (9), 574 (1992). C. Chang-Hasnain et al., Appl. Phys. Lett. 58, 11 (1991). P. Besnard, X. Jia, R. Dalgliesh, A. D. May, G. Stephan, J.0.S.A.B 10 (9), 1605 (1993). 3.

Demonstration of all-optical set-reset operation in a GaInAsP waveguide bistable device

Optical bistability was successfully demonstrated in a GaInAsP waveguide with a distributed feedback structure. Further study toward improving the on-off ratio (high to low output level) is now under way.