Zuoren Dong

Experimental investigation of optical beam deflection based on PLZT electro-optic ceramic

Based on the optical characteristics of PLZT (Lead Lanthanum Zirconate Titanate) electro-optic ceramic, two kinds of electro-optical deflectors, triangular electrode structure and optical phased array technology, are studied in detail by using transverse electro-optic effect. Theoretically, the electro-optic deflection characteristics and mechanisms of the deflectors are analyzed; experimentally, the optical characteristics of ceramic wafer, such as the phase modulation, the hysteresis and the electro-induced loss characteristics, are measured; a systematic experiment is designed to verify the theoretical results. The effect of temperature on the performance of deflector is also investigated. Comparing with both structures deflectors, the optical phased array technology has a higher angle scanning resolution, however, it has a relative small deflection angle. OCIS codes: (230.2090) Electro-optical devices; (160.2100) Electro-optical materials; (060.5060) Phase modulation.

Non-line-of-sight optical scattering communication based on solar-blind ultraviolet light

Non-line-of-sight (NLOS) optical scattering communication (OSC) is studied theoretically and experimentally. Making use of single scattering propagation model, properties of NLOS optical scattering channel are simulated numerically under some typical condition. The results show that the path loss of the channel is quite large, and becomes larger as apex angle of the transmitter and receiver increases. The results also show that the pulse transmitted from the source is broadened significantly after propagating in the NLOS optical scattering channel. It will limit the available bandwidth of the channel, and probably cause intersymbol interference in digital communication systems. Moreover, some elementary experimental facilities of NLOS UV communications are constructed. A UV digital communication system based on 254nm low pressure mercury lamp has been set up, and the BER of the system is about ~10-4 when the transmitter apex angle is 60 degree and bit rate is 1200bits/s. and NLOS light propagation experiments were conducted by exploiting a 370nm UV light-emitting diode (LED). With the progress of devices based on semiconductor in UV band, NLOS optical scattering communication with small volume and low power may be achieved in future.

Robust CCD photoelectric autocollimator for outdoor use

A robust charge-coupled device (CCD) photoelectric autocollimator for outdoor use is designed and demonstrated. The influence of outdoor conditions on the signal-to-noise ratio (SNR) and imaging quality of the measuring system is experimentally analyzed. The pulse width modulation technology is applied to the automatic feedback control of the actively regulated illuminating light source of the measuring system to maximize SNR while avoiding image saturation. A Fourier phase shift method for subpixel estimation is adopted to achieve high-accuracy measurement in the presence of noises. Experimental results indicate that the technologies proposed here largely improve the measuring stability, dynamic range, and accuracy of the CCD photoelectric autocollimator used outdoors.

An anti-noise subpixel algorithm based on phase-shifting of Fourier transform and its application in CCD photoelectric autocollimator

An anti-noise subpixel algorithm of phase-shifting of fundamental frequency was presented based on the phase-shifting of Fourier transform and the anti-noise characteristics of low-frequency part of the phase spectrum of the image. The essence of the algorithm is that the displacement caculation of the image is replaced by the movement caculation of the coordinate, which makes the phase of the fundamental frequency zero under different coordninates when image position changes. Under the circumstances that the image of the CCD autocollimator is polluted by the noises caused by tempreture, the measuring accuracies of the normally-used barycenter, edge detection, Gaussian fitting algorithm and the algorithm presented in this paper were compared. Experiment results show, the subpixel algorithm demonstrated here has the advantages of strong anti-noise ability and high precision. The reliability of the algorithm is also disproved by the peak location of the reconstructed image after the removal of higher harmonics. When applied to the one-dimensional CCD photoelectric autocaollimator used in field conditions, fine linearity and ±3// measurement accuracy were simutaneously obtained in the whole ±3600// measurement range when the temperature varies between -400C-600C.

Beam steering of external cavity diode laser by an intracavity electro-optic ceramic deflector

A novel beam-steering external cavity diode laser using an intracavity lead lanthanum zirconate titanate (PLZT) electro-optic ceramic deflector is proposed and demonstrated experimentally. The laser consists of a semiconductor laser with single mode fiber coupled output, polarization controller, PLZT electro-optic ceramic deflector, and output concave mirror. By applying proper driven electrical signals on the PLZT electro-optic deflector, the beam deflection angle achieves 5.8 mrad at 1 000 V. A high-speed beam-steering property with less than 120-ns switching time is also observed. Moreover, a good beam quality with Gaussian spatial profile and a linear polarization state are obtained.

Two-coordinate dynamic photoelectric autocollimator based on single linear CCD

A competitive homemade two-coordinate autocollimator is presented, which is able to measure the angle along the horizontal and vertical axis by using a single linear CCD to detect the three image point positions of the N shape reticle on the CCD, with total measurement error no greater than 5urad in the measurement range of ±2100urad and the dynamic response frequency 2KHz.

Fabrication and optical characteristic investigations of thick PLZT waveguide films on Pt/Ti/Si substrate by using the sol–gel method

A fabrication process of thick lead lanthanum zirconate titanate (PLZT) waveguide films (9/65/35) on a Pt/Ti/Si substrate is introduced by using the sol?gel method. Two kinds of substrates (planar and reversed ridge configuration) are provided to deposit thick PLZT waveguide films in order to reduce the transmission loss for its application in photoelectron components or devices. The technique process of film growth is described in detail. The optical characteristics of the PLZT waveguide film, such as transmission spectrum, optical loss, refractive index and electro-optic effect, are also investigated and discussed.

Dynamic auto-collimation method for performance inspection of optical tracking devices with gimbaled mirrors

A dynamic auto-collimation system for inspecting the performances of optical tracking devices is proposed and analyzed in the paper, which includes a simulation of a moving target and the gimbaled mirror embedded in the optical path of auto-collimation to construct a close loop of measurement. In this system, the gimbaled mirror tracks the movement of simulation target and the auto-collimation gives the tracking deviation and feedback to the system. Static pointing accuracy, response to step movement and dynamic tracking performance of the tracking device under test were measured for the two axes of gimbaled mirror. The researched result shows that the method is effective in indoor inspection of static and dynamic performances of optical tracking devices constituting of gimbaled mirrors and other large angle beam steering devices.

The Effect of Temperature on Characteristics of PLZT Electro-optic Deflector

The effect of temperature on characteristics of lead lanthanum zirconate titanate (PLZT) electro-optic deflector is investigated. We find that, with temperature increasing, the characteristic of the deflector is affected largely and the deflection angle will reduce for the same applied voltage, and that the quadratic hysteresis characteristic of PLZT ceramics will also be varied.

Study of optical phased-array technology based on PLZT electro-optic ceramic

Based on the optical characteristics of PLZT electro-optic ceramic, a novel optical phased-array beam deflector with the transverse electro-optic effect is proposed. The deflection characteristic and mechanism of the deflector is analyzed theoretically and experimentally.