Apichai Bhatranand

Monolithic integration of semiconductor optical amplifier and photodiode through quantum well intermixing

Monolithic integration of semiconductor optical preamplifier and photodiode is demonstrated through a two-stage laser-induced quantum well intermixing process. The integrated device has a peak responsivity of 5.7 A/W and a 3-dB bandwidth of 14.7 GHz.

Polarizing triangular cyclic interferometer for characterizing optical samples with birefringent properties

This paper presents the polarizing triangular cyclic interferometer (pTCi) for characterizing optical samples with birefringent properties such as half- and quarter-wave plates. The interferometric system was set up to analyze the phase retardation of wave retarders in both qualitative and quantitative aspects. For the qualitative aspect, the distinct signal outputs from the inspected birefringent components oriented at particular angles are employed to distinguish different types of optical devices. For the quantitative aspect, the same arrangement could determine the phase difference γ of unknown retarders, so that it could be used to characterize types of samples. The experimental results showed the corresponding results obtained from both mentioned aspects where γ were measured to be 89.62° and 177.17° for half- and quarter-wave plates, respectively. The pTCi has been proved to be a proper scheme to characterize optical samples with birefringent properties.

Electro-optic barium titanate waveguide modulators with transparent conducting oxide electrodes

Barium titanium waveguide electro-optic modulators with Al-doped ZnO transparent conducting oxide electrodes are realized. Low half-wave voltage of 1.1 V and half-wave voltage length product of 1.1 V-cm are achieved at 1550 nm wavelength.

Integration of Semiconductor Preamplifier and Wideband Photodiode Using Quantum Well Intermixing Technology

Photonic integration of a semiconductor optical preamplifier and a wideband photodiode is demonstrated through a two-stage laser-induced quantum well intermixing process. The integrated device has a sensitivity of -27.7 dBm at 10 Gb/s.

Strain induced waveguide electro-optic modulators in barium titanate crystal

Strain-induced waveguide electro-optic phase modulators in barium titanium (BaTiO3) crystal are demonstrated. Low loss waveguide and low half-wave voltage length product are achieved at 1550 nm wavelength regime.

Temperature effects on wavelength calibration of the optical spectrum analyzer

This paper presents the investigation of the temperature effects on wavelength calibration of an optical spectrum analyzer or OSA. The characteristics of wavelength dependence on temperatures are described and demonstrated under the guidance of the IEC 62129-1:2006, the international standard for the Calibration of wavelength/optical frequency measurement instruments – Part 1: Optical spectrum analyzer. Three distributed-feedback lasers emit lights with wavelengths of 1310 nm, 1550 nm, and 1600 nm were used as light sources in this work. Each light was split by a 1 x 2 fiber splitter whereas one end was connected to a standard wavelength meter and the other to an under-test OSA. Two Experiment setups were arranged for the analysis of the wavelength reading deviations between a standard wavelength meter and an OSA under a variety of circumstances of different temperatures and humidity conditions. The experimental results showed that, for wavelengths of 1550 nm and 1600 nm, the wavelength deviations were proportional to the value of temperature with the minimum and maximum of -0.015 and 0.030 nm, respectively. While the deviations of 1310 nm wavelength did not change much with the temperature as they were in the range of -0.003 nm to 0.010 nm. The measurement uncertainty was also evaluated according to the IEC 62129-1:2006. The main contribution of measurement uncertainty was caused by the wavelength deviation. The uncertainty of measurement in this study is 0.023 nm with coverage factor, k = 2.

Measurement of phase retardation in a liquid crystal variable wave retarder using a polarizing triangular interferometer

The purpose of this study aims to investigate a new method for measuring the phase retardation caused by the induced birefringence from a liquid crystal sample. The method uses a polarizing triangular interferometer whose arrangement requires just a few optical devices. The liquid crystal phase retarder under investigation is inserted into an optical path of the triangular interferometer. The modified interference beam, therefore, is used to characterize the sample property. The method is proved to be effective and suitable for the measurements of polarization related parameters of the optical devices.

An improved method of ONU placement on multi-hop wireless connections for Hybrid Wireless-Optical Broadband Access Network

This paper proposes a method to improve ONU placement based on multi-hop wireless connections for hybrid wireless-optical broadband access network (WOBAN). The optimum local search based on simulated annealing technique is utilized as an optimization approach to find optimal placements of ONUs. The multi-hop strategy allows reduction in number of initial primary ONUs. The simulated results showed that the average routing distance from the proposed method can be successfully reduced up to approximately 20%, depending on the number of wireless connection hops.

A compensation method of light source dynamic tc improve stability of optical fiber-based biosensor

This paper presents a compensation method of light source dynamic to improve a measurement stability of samples light transmittance using our fiber optic-based sensor. In principle, dynamic input and transmitted lights are measured for insertion loss calculation of an empty tube. The loss is compensated in the actual light transmittance calculation of a solution sample. Comparison experiments were conducted with double concentration of red syrup solutions. The coefficient of variation (CoV) was used as the stability metric. Results from 2 trials of our double concentration solution samples showed that the COV ranges around 0.987-1.411%. The results from our dynamic compensation approach strongly demonstrated superior measurement stability to the uncompensated approach in which its CoV ranges around 9.075-9.808%.

Linear electro-optic modulators with wide dynamic range through dielectric thin films

Optical feedback techniques with double layer thin films for extending spurious-free dynamic range (SFDR) of an electro-optic modulator is described. An improvement of 11 dB SFDR compared to the typical electro-optic modulators is demonstrated.