The first merit of the holographic data storage (HDS) system is its high storage capacity. In practice, it is well known that the total capacity for the storage medium depends on the appropriate ratio of ON and OFF pixels within data pages. Therefore, we propose a modulation code that can control the ratio of ON and OFF pixels. We refer to this code as “tone-controllable code”. In this paper, we introduce the encoding/decoding rules and simulate the bit error rate (BER) performance of the tone-controllable codes having various ratios of ON and OFF pixels.

In this paper, we propose k/(k+1) tone-controllable (TC) codes for holographic data storage system which can control the rate of ON and OFF pixels within each data page. We introduce a method for making an encoding table for the proposed k/(k+1) TC code and we analyze the features of the proposed code. In addition, we analyze the k/(k+n) TC code where n is 1–5.

A series of poly(oligothienylene vinylenes) (PTmVs, m = 2–4) with a varying number of consecutively bound thienylene rings are successfully prepared in thin films by chemical vapor deposition polymerization (CVDP) using the corresponding bis(halomethyl)thiophenes as starting materials. The chemical and electronic structures are studied spectroscopically and also by cyclic voltammetry. Top‐gate field‐effect transistors are fabricated by two consecutive CVDP cycles of PTmV and poly(p‐xylylene) followed by the deposition of a Au gate electrode. In the case of a PT3V active layer, a field‐effect mobility value of 0.5 × 10–4 cm2 V–1 s–1 is obtained.

Graphene-enhanced resonance Raman scattering (GERRS) was performed for the detection of three different metallo-octaethylporphyrins (M-OEPs; M = 2H, FeCl, and Pt) homogeneously thermal vapor deposited on a graphene surface. GERRS of M-OEPs were measured using three different excitation wavelengths, λ(ex) = 405, 532, and 633 nm, and characterized detail vibrational bands for the identification of M-OEPs. The GERRS spectra of Pt-OEP at λ(ex) = 532 nm showed ~29 and ~162 times signal enhancement ratio on graphene and on graphene with Ag nanoclusters, respectively, compared to the spectra from bare SiO2 substrate. This enhancement ratio, however, was varied with M-OEPs and excitation wavelengths. The characteristic peaks and band shapes of GERRS for each M-OEP were measured with high sensitivity (100 pmol of thermal vapor deposited Pt-OEP), and these facilitate the selectively recognition of molecules. Also, the peaks shift and broadening provide the evidence of the interaction between graphene and M-OEPs through the charge transfer and π-orbital interaction. The increase of graphene layer induced the decrease of signal intensity and GERRS effect was almost not observed on the thick graphite flakes. Further experiments with various substrates demonstrated that the interaction of single layer of graphene with molecule is the origin of the Raman signal enhancement of M-OEPs. In this experiment, we proved the graphene is a good alternative substrate of Raman spectroscopy for the selective detection of various metalloporphyrins with high sensitivity.

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