Search

Polarization of an optical frequency comb is electrically controlled using a waveguide electro-optic phase modulator (WG-EOM). Owing to the low operation voltage and wide electric bandwidth of the WG-EOM, fast polarization control is possible. It is found that birefringence of the WG-EOM and polarization-maintaining optical fibers causes polarization-dependent pulse separation, which makes polarization control of the optical frequency comb impossible. Therefore, compensation of the birefringence is required for polarization control. In the experiment, a delay line in free space is used for birefringence compensation, and pulse-to-pulse polarization control of an optical frequency comb (with a repetition rate of 100 MHz) is demonstrated.

Two huge earthquakes struck Kumamoto, Japan, in April 2016, forcing residents to evacuate. Few studies have reported early-phase disease and injury trends among evacuees following major inland earthquakes. We evaluated the trends among evacuees who visited a medical clinic in a shelter located at the epicenter of the 2016 Kumamoto earthquakes. The clinic opened on April 15, the day after the foreshock, and closed 3 weeks later. We reviewed medical charts related to 929 outpatient visits and conducted descriptive analyses. The evacuees experienced mild injuries and common diseases. The types of diseases changed weekly. Elderly people needed medical support for longer than other age groups. Future earthquakes may be inevitable, but establishing arrangements for medical needs or making precautions for infectious diseases in shelters could reduce the effects of earthquake-related health problems.

Laser frequency stabilization is one of the essential technique in atomic, molecular, and optical physics, quantum optics, optical communications, and fundamental physics. Optical offset locking is the technique to stabilize optical frequency of a single-mode laser (slave laser) with respect to another well-stabilized laser (master laser). Optical phase lock loop (OPLL) [1] is one of the offset locking schemes, with which the slave laser frequency can be stabilized very precisely (less than the uncertainty of 10−18). However, especially in noisy experimental circumstances, the OPLL does not work because its capture range is not so wide that the locking fails for large amount of frequency jitters. In order to keep the locked condition, another offset locking with wider capture range is sometimes required. Examples of such locking schemes are digital processing technique, optical frequency locking to resonance frequency of a high-finesse cavity [2], offset locking with an electrical delay line [3], and offset locking with electric LC resonant circuit [4]. The offset locking with the electric LC circuit (LC locking) has been introduced by W.-Y. Cheng et al, and with employing this scheme with the OPLL the beat-note frequency can be stabilized as precise as one millihertz.

For scan-free high-resolution direct-comb spectroscopy, mode spacing of an optical frequency comb is reduced down to 260 kHz by phase modulation. It turns out that time-domain signal is degraded by averaging because of slow optical path length fluctuations and fast optical pulse timing jitter. In this study, compensation of these effects is introduced, and signal degradation by averaging is avoided. With demonstrations of direct-comb spectroscopy with the narrow-mode-spacing optical frequency comb, Doppler-limited absorption spectrum of methane and reflection spectrum from an optical ring cavity are observed. As a result, detailed resonance spectral line profile of 8 MHz linewidth for the optical ring cavity is obtained in 50 ms measurement time.

We introduce a simple scheme for mode density multiplication of an optical frequency comb by square of an arbitrary integer with phase modulation. The mode density of an Er fibercomb is multiplied by 42.

A simple scheme without dither to obtain an error signal for the stabilization of the coupled-cavity configuration for efficient fourth harmonic generation of continuous-wave lasers is proposed and demonstrated. This scheme is an analogue of the noise immune cavity enhanced optical heterodyne molecular spectroscopy (NICEOHMS) technique. In the proposed scheme, the robust stabilization is expected in comparison with the dither lock technique. In the demonstration, the stabilization of the coupled resonant cavity at the resonance is successfully achieved without the noise caused by the dither.

Frequency quadrupling of a continuous-wave laser is carried out in coupled cavities with the stabilization to the resonance. The fourth harmonic generation in the coupled cavities is expected to be more efficient than in the two build-up cavity configuration in tandem, because input couplers, which increase the optical loss of the cavity, are not required. The cavity length is stabilized by the feedback of the error signal obtained by the cavity length modulation. In the present demonstration, the ultraviolet beam of 6 μ W at 238 nm is obtained by the fourth harmonic generation of the near infrared laser of 180 mW at 952 nm. This output power is expected to become higher ( ∼ 1.7 mW ) when the cavity setup is optimized.

A scheme to resolve individual comb modes by heterodyne detection with a continuous-wave laser for direct comb spectroscopy is proposed and demonstrated. This is simple and suitable for application to high-resolution spectroscopy.

We demonstrate frequency stabilization of a modulation-free laser to a saturated absorption spectral line of atoms in a transversal magnetic field. This stabilization scheme has been proposed for wide capture range in comparison with the dichroic atomic vapor laser lock (DAVLL) scheme and demonstrated for a Doppler-broadened spectral line in J. Opt. Soc. Am. B, 26, 1216 (2009). In this paper, a 1083-nm external-cavity laser diode is frequency-stabilized to the sub-Doppler spectral line of helium transition ( 2 3 S 1 , m J = 0 ↔ 2 3 P 0 ). Even though the error signal shape strongly depends on the pump beam polarization, the stabilized frequency is expected to be insensitive to the pump beam polarization.

Conclusion: The prediction of subtype and the affected ear of benign paroxysmal positional vertigo (BPPV) derived from the answers to our questionnaire can support the definitive diagnosis of BPPV. Objectives: We examined to what extent the diagnosis of subtype and the affected ear of BPPV judged from answers to a questionnaire agreed with the diagnosis decided by the results of the positional nystagmus test. Methods: We asked the following questions: ‘What kind of head movements induce vertigo?’ and ‘How long does the vertigo continue?’. As for the affected ear, we asked which ear was lower during stronger vertigo when induced in a supine position or during sleep. Results: The percentages of correct diagnosis speculated by the combined answers were 69% in posterior canal-type BPPV, 48% in BPPV with geotropic nystagmus, and 39% in BPPV with apogeotropic nystagmus. The percentage of correct diagnoses of the affected ear was more than 80%.

We introduce a simple scheme for mode-density multiplication of an optical frequency comb (OFC) by a factor of square of an arbitrary integer N using phase modulation. This scheme is employed to multiply the mode density of an erbium-doped fiber laser OFC (repetition rate of 66.87 MHz) by factors of 42, 82, and 3 · 42 using an electro-optic phase modulator. The OFC multiplied by 42 is applied to direct-comb spectroscopy of methane with a spectral resolution of 4.18 MHz.

Objectives: To evaluate the impact of tamsulosin treatment on erectile function in patients with lower urinary tract symptoms (LUTS). Methods: Seventy-five patients with LUTS received tamsulosin 0.2 mg once daily for 3 months. Subjective efficacy was assessed by International Prostatic Symptom Score (IPSS) for LUTS and International Index for Erectile Function 5 (IIEF5) for erectile dysfunction (ED). Objective efficacy was assessed by prostate volume and urine flow rate. All measurements were performed at baseline and month 3. On the basis of IPSS ratio (month 3/baseline), the patients were classified into good responders (≤0.75) and poor responders (>0.75). Good responders to ED were defined as the patients who improved IIEF5 score 3 or more. Results: Seventy-four subjects completed the study. IPSS score showed significant improvement, but IIEF5 score showed no significant change. Forty-three patients (58%) were classified into good responders to LUTS. The baseline score of IIEF5 in the good responders was significantly higher than that in the poor responders. Negative correlation was recognized between IPSS ratio and baseline score of IIEF5. Nine patients (13%) were able to classify into good responders to ED, who had significantly smaller prostate volume and showed significantly lower IPSS ratio. Conclusions: The tamsulosin therapy for LUTS patients showed a significant improvement of LUTS, but no significant change of erectile functions. The better response to LUTS was seen in the milder ED patient. Tamsulosin therapy may be effective not only on LUTS but also on ED in the patients who have small prostate.

The interface stress distributions in composite cylinders of steel (solid cylinder) and epoxy (hollow cylinder) under push-off loads are analyzed using axisymmetrical theory of elasticity as a three-body contact problem. In the numerical calculations, the effects of Young’s modulus and the diameter of solid cylinder on the interface stress distribution are examined. In addition, the effects of the diameter of supported hollow cylinder and the stress distribution due to the applied push-off loads are also examined. It is found that the normal stress at the interfaces increases as Young’s modulus of solid cylinder decreases, the diameter of solid cylinder and the diameter of supported hollow cylinder increase. It is also found that the shear stress at the interfaces increases as the diameter of supported hollow cylinder increases, Young’s modulus and the diameter of solid cylinder decrease. Singular stresses occur at the edges of the interfaces. A valid method for estimating the singularity is proposed and the discussion is made. Using the interfaces stresses obtained from the numerical analysis and analogous tests, the push-off strength of composite cylinders is estimated. The experiments to measure composite cylinders strength are carried out. It is seen that a rupture initiates at the lower edge of the interface area when the push-off loads are applied to the upper end of solid cylinder. For verification of the present analysis of the interface stress distributions, finite-element method (FEM) is also carried out. The numerical results of the interface stress distributions and the strength are in fairly good agreement with the experimental results and the FEM results. The axisymmetrical theory of elasticity is more rational compared to the shear lag theory in examining the stress singularity and considering the normal stress and shear stress at the interfaces at the same time. Finally, as an example, it is observed that the weight of composite cylinders is lighter by 48.1% than that of the structure with the same of steel material for obtaining the same strength.

Rhoキナーゼ阻害剤の塩酸ファスジルは, 1) 血管拡張・血流改善作用, 2) 神経・シナプス再生作用を有し, 突発性難聴の主たる病態の1つとされる内耳血流障害を改善させ, 同時に, ラセン神経節細胞―有毛細胞間のシナプス結合の修復を促すことで, 突発性難聴に対して優れた治療効果を示すことが期待される薬剤である。塩酸ファスジル併用ステロイド治療を突発性難聴10症例に対して行い, 完全回復が9例と極めて良好な治療効果が得られた。血管収縮物質エンドセリンによる内耳微小血管の収縮は, 突発性難聴の内耳病態, 分子機構の一つと示唆されている。エンドセリンによる砂ネズミ蝸牛軸動脈の収縮は, Rhoキナーゼ阻害薬により濃度依存性に抑制される。塩酸ファスジル併用ステロイド治療は, エンドセリンによる内耳循環障害を軽減し, ステロイド単剤治療の効果をより高め, 突発性難聴の治療成績を著明に向上させ得る新規治療法となる可能性が示唆された。

A 46-year-old man refer to us because of hemospermia. The prostatic gland was normal in size and consistency at rectal examination. Serum prostate specific antigen was 7.04 ng/ml. Magnetic resonance imaging showed an area of low signal intensity on T2-weighted images in the left peripheral gland, possibly indicative of carcinoma. Transrectal prostate biopsy was performed after intravenous administration of piperacillin. He developed chills and fever (39 degrees C) the next morning following biopsy. He was taken unconscious into the hospital where a diagnosis of septic shock caused by Escherichia coli was made. Five days later, he died. His general condition deteriorated notwithstanding intensive treatment. Postmortem blood cultures were positive for a piperacillin resistant Escherichia coli. Histological examination of the biopsies showed a benign prostatic hyperplasia. Autopsy showed diffuse tissue damage in the heart, lung, liver and kidneys. The prostate had numerous microabscesses. Currently, transrectal prostate biopsy is considered a generally reliable procedure to detect adenocarcinoma of the prostate. Our case seems to the sixth case report of fatal complications.

We have demonstrated direct-comb molecular spectroscopy in which an individual-comb mode is resolved by heterodyne detection with a continuous-wave (cw) laser. This simple, fast, and sensitive technique was demonstrated for atomic spectroscopy in [ Appl. Phys. Lett.101, 051105 ( 2012)], but is more suitable for molecular spectroscopy. Four rotation-vibration transitions of methane have simultaneously been recorded in a Doppler-limited resolution using a spectrally broadened comb based on an Er-doped fiber laser and a cw 1651-nm distributed-feedback laser diode. Even though the power level of the comb modes and the sample absorption are weaker than those of the previous studies, in this work the cw laser frequency is stabilized to one of the comb modes, and the data are thereby averaged for extended periods of time, resulting an improvement in sensitivity.

Optical bistability in a passive ring cavity with no designed nonlinear materials is experimentally observed in the near-infrared region. The nonlinear material that induces the optical bistability is considered to be water molecules in atmosphere. In the model calculation, it is found that the optical bistability is induced by transversal distribution of optical power-dependent refractive index of water in the Gaussian beam, which causes the power-dependent Gouy phase shift in the cavity. The model calculation agrees qualitatively with the experimental results. This result suggests that the Gouy phase shift has an effect on cavity-enhanced molecular spectroscopy.

Retroperitoneoscopic ureterolithotomy was successfully performed in two patients with impacted upper ureteral stone. The retroperitoneal space was extended using a balloon dissector and four ports were established into the retroperitoneal space according to Gaur's procedure (1993). The impacted ureteral stone was removed after the ureter was incised using a hook electrode. An indwelling splint or stent was placed in the ureter. The incised ureter was not sutured and an indwelling drain was placed in the retroperitoneal space. Urine leakage ceased within 3 days postoperatively. With regard to complications, the first patient developed wound infection caused by methicillin-resistant Staphylococcus aureus and the second patient had abscess formation in the psoas muscle. Retroperitoneoscopic ureterolithotomy should be useful as an alternative treatment for impacted ureteral stones because it involves minimal postoperative pain.

Gamma/delta T cell lymphoma is very rare, and usually occurs as an extranodal tumor. We describe the case of a 16-year-old Japanese man with an unusual nodal gamma/delta T cell lymphoma with generalized lymphadenopathy and bone marrow involvement. No tumor involvement was observed in the liver, spleen, or nasal cavity. Examination for surface antigens on lymphoma cells revealed a unique phenotype, positive for CD3 and T cell receptor (TCR) gamma/delta, but negative for CD2. Genotypic analysis revealed the tumor to be of monoclonal origin and characterized by TCR gamma-chain gene rearrangement, but there was no rearrangement of the TCR beta-chain gene. Our patient’s tumor responded to combination chemotherapy and subsequent allogeneic bone marrow transplantation from an HLA-matched unrelated donor. He has remained well and free of disease for 35 months.

Background: Acute graft-versus-host disease still represents the major factor that limits successful allogeneic bone marrow transplantation. Cytokines released by type 1 T-helper cells are thought to play a pivotal role in acute graft-versus-host disease. Objective: This study was performed to investigate whether the serum levels of soluble IL-2 receptor, IL-12, IL-18, and IFN-γ were associated with the manifestation of acute graft-versus-host disease. Methods: Serum cytokine levels were measured by sandwich ELISA in 18 patients who underwent allogeneic bone marrow transplantation. Results: Serum levels of soluble IL-2 receptor, IL-12, IL-18, and IFN-γ were increased in patients in whom acute graft-versus-host disease developed. However, only serum soluble IL-2 receptor levels were significantly related to disease severity. Serum levels of IL-12 and IL-18, both of which are mainly produced by activated macrophages, were increased in different phases of acute graft-versus-host disease, especially grade I. Serum levels of soluble IL-2 receptor and IFN-γ were significantly elevated in patients with fever. Conclusion: Serum levels of soluble IL-2 receptor were more closely related to the severity of acute graft-versus-host disease than those of IL-12, IL-18, and IFN-γ. (J Allergy Clin Immunol 2000;106:S45-50.)

Frequency-doubled beam of the higher-order Laguerre–Gaussian mode is obtained with a high power (2 mW) aiming at an investigation of the interaction between the Laguerre–Gaussian beam and ions in a radio-frequency ion trap. For a sufficient beam power, the Hermite–Gaussian beam is obtained at first, frequency-doubled, and then mode-converted to the Laguerre–Gaussian mode. The beam profile is analyzed theoretically.

The repetition rate of an erbium-doped fiber comb is multiplied by an optical cavity for filtering, and the optical spectral distribution is broadened in a highly nonlinear fiber. For erbium-doped fiber combs, filtering cavities are commonly used to obtain the high-repetition-rate combs by the repetition rate multiplication. After the multiplication, optical spectral broadening by a highly nonlinear fiber is necessary for applications to optical frequency measurements in broad bandwidth and astronomy. In this study, the broadened spectrum covers over the range from 1050 to 2250 nm, which is over an octave so that the determination of the filtered mode numbers is feasible. The optical power of the broadened beam within a narrow optical bandwidth is also measured in the time domain and in the frequency domain to examine the broadening property.

Acute graft-versus-host disease (aGVHD) is a serious complication of allogeneic peripheral blood stem cell transplantation (PBSCT). Patients with severe aGVHD not responding to treatment with steroids have a poor prognosis. We treated three patients with severe aGVHD refractory to steroids with infliximab. Patients (MDS 1, NHL 1, ALL 1) developed grade II-IV GVHD at a median of 13 days (range 9-17) after non-myeloablative PBSCT (HLA mismatched). All patients had received treatment with high-dose steroids for a median of 7 days (range 7-10) in addition to mycophenolate mofetil (MMF) (one). Infliximab was given in 3 weekly doses of 5 mg/kg. In one of three patients a partial resolution of diarrhea and minor improvement of skin were observed. One patient died with refractory GVHD. Infliximab is apparently an effective drug for the treatment of aGVHD, but can be more effective at doses of 5 mg/kg or higher and/or by administering it repeatedly every week.

Clear eye opening at 28-Gbit/s direct modulation up to 75°C is achieved with 1.3-μm buried heterostructure AlGaInAs-MQW DFB laser. No failure had occurred at high optical output power aging test over 7000 hours.

Thrombotic microangiopathy (TMA) impairs long-term survival after allogeneic hematopoietic stem cell transplantation (HSCT). As the allogeneic HSCT procedure has developed, addressing risk factors for TMA has become more complicated. The aim of this study was to investigate the impact of transplant-associated factors on TMA incidence in patients who have undergone HSCT in various settings. One hundred twenty-three consecutive allogeneic HSCT patients with hematologic diseases receiving myeloablative and reduced-intensity conditioning were evaluated retrospectively. Of 123 patients, 22 (17.9%) developed TMA after HSCT. Multivariate analysis showed the significance of GVHD grade II-IV, and the use of FK506 and the use of high-dose busulfan (Bu) (16 mg/kg) persisted. The hazard ratios of the use of FK506, the use of high-dose Bu (16 mg/kg), and GVHD grade II-IV for TMA were 8.7 (95% CI 2.0-37), 5.7 (95% CI 1.5-21), and 3.4 (95% CI 1.3-9.1), respectively. In the present study, reduced-intensity conditioning did not have an advantage over myeloablative conditioning in decreasing the incidence of TMA after HSCT. Our results also showed that high-dose Bu (16 mg/kg) for the conditioning and FK506 for the prophylaxis of GVHD might contribute more significantly to TMA onset after HSCT than other agents.

We evaluated the performance of a fully-automated hematology analyser CELL-DYN 4000 (CD4000; Abbott Laboratories, CA, USA) for T-lymphocyte subset analysis using the samples from 58 patients with hematological disorders. A flow cytometer (CytoronAbsolute; Ortho Diagnostics, NJ, USA) was used for comparison. Good correlations were shown between CD4000 and CytoronAbsolute for the of CD3(+), CD4(+), and CD8(+) T-lymphocyte counts (for each of correlations, r = 0.992, 0.992, and 0.969, respectively). This good correlation was sustained even in 24 cases in which the CD4(+) T-lymphocyte counts were less than 200/microl. In this group the correlation coefficients (r-values) for the comparisons between CD3(+), CD4(+), and CD8(+) T-lymphocytes measured by CD4000 and CytoronAbsolute were 0.991, 0.976, and 0.990, respectively. The CD4000 T-lymphocyte assay is a completely automated method, and does not require opening of the sample tube, which reduces exposure to any biohazards such as HIV. Furthermore, the method is rapid and requires only 7 min for completion of the analysis.

Frequency tripling of cw 840 nm laser is obtained for laser cooling of magnesium ions. This beam at 280 nm is expected to improve the long-term and short-term stability of optical frequency standard by laser-cooled ions. Our frequency conversion system is essentially applicable to other wavelength.

We report here the sixth known case of metastatic renal tumor of thyroid carcinoma. In 1999, a 37-year-old man was referred to us with a left renal mass found incidentally by ultrasound during an annual check-up. Computed tomography (CT) revealed a well-defined, hyperdense mass 3 cm in diameter in the middle of the left kidney. Left radical nephrectomy was performed under the preoperative diagnosis of renal cell carcinoma. Histologically, the tumor was metastatic of typical papillary thyroid carcinoma.

Nonlinear effects by intense optical field on mid-infrared spectral lines (∼3 μm) are discussed. Recent development of intense mid-infrared coherent radiation makes nonlinear mid-infrared spectroscopy possible. In the mid-infrared region, the transversal relaxation process is important compared to the visible or near-infrared region. In the analysis, a two-energy-state system is discussed. The intense pump beam scattering spectral lines (Mollow triplet) and the absorption spectral lines of the probe beam with the intense pump beam are calculated.

Background: We report here on a third case of squamous cell carcinoma (SCC) of the renal pelvis extending to the inferior vena cava. Methods/Results: A 48-year-old man was diagnosed with an advanced left renal pelvic tumor on computed tomography. He had undergone extracorporeal shock wave lithotripsy for left staghorn calculi 10 years ago. An inferior vena cavagram showed tumor thrombus extending to the inferior vena cava. Percutaneous left renal biopsy revealed SCC. The patient received three courses of combination chemotherapy with cisplatin, bleomycin and etoposide. However, 1 month after the last course of chemotherapy, he died of cancer progress. Conclusion: This is the third case of SCC of the renal pelvis extending to the inferior vena cava in the world.

We report a 26-year-old male patient with acute myelocytic leukemia and hepatosplenic candidiasis during his clinical course. His hepatosplenic candidiasis was refractoty to itraconazole and fluconazol. He developed serious side-effect such as renal dysfunction, when conventional amphotericin B was given. Then he was treated with liposomal amphotericin B (Abelcet). This therapy was safe and effective for him. He was able to be treated with 3075 mg of a liposomal amphotericin B. This was ten times as much as the dose of conventional amphotericin B which was given earlier until amphotericin B was stopped because of renal dysfunction. Liposomal amphotericin B seems to be a safe and effective therapy for systemic fungal infectin and should be considered more in Japan.

A robust laser-frequency-locking scheme to atomic transitions is proposed and demonstrated. In this scheme, dispersion of the Zeeman-shifted atoms instead of absorption in the dichroic atomic vapor laser lock (DAVLL) [Appl. Opt.37, 3295 (1998)] is measured and used as an error signal for stabilization feedback. The error signal of the proposed scheme can provide a wide locking range. Experimental demonstration with the transition between 5d 2D3/2 and 6p 2P1/2 of Ba+ is carried out for a grating feedback external-cavity laser diode at 650 nm.

Peripheral blood stem cell harvest (PBSCH) has been widely performed for rescue following high-dose chemotherapy or as an alternative to BMT for allogeneic stem cell transplantation. However, severe complications, which caused sudden death, were reported in PBSCH from healthy donors. Recent cumulative evidence shows that decrease in cardiovascular signal variability of the R-R period (heart rate variability, HRV) is strongly associated with sudden death and/or cardiac event after a myocardial infarction. Furthermore, usefulness of HRV as a clinical tool has been explored in numerous conditions such as hypertrophic cardiomyopathy, obstructive sleep apnea, diabetic neuropathy, and various neurological alterations. Two types, time domain and frequency domain, are included in HRV analysis. In this study, we investigated HRV during and after apheresis for PBSCH in 23 cases [8 autologous transplant patients, 15 allogeneic transplant donors; 8 men, 15 women; median age 47 years (27–55)]. Date from 24-hour ambulatory ECG recordings were analyzed with R-R data analysis software (MemCalc/CHIRAM version 1, Suwatrust, Tokyo, Japan). Acknowledged simple markers in time domain analysis are the standard deviation of all normal beats (SDNN) and the square root of the mean of the sum of squared differences between adjacent normal-to-normal intervals (r-MSSD). On the other hand, markers in frequency domain analysis include LH, low frequency power (0.04–0.15Hz); HF, high frequency power (0.15–0.4 Hz); LH/HF ratio; VLF, very low frequency power (0.003–0.04 Hz); and ULF, ultra low frequency power (

薄層電波吸収体を実現するために, 誘電体を利用する方法が考えられる.本文は厚さに対する完全整合波長 (2πl/λ0) と複素誘電率の関係を求め, 単層構造で整合し得ない材料に対しては, 2層目をtanδe補正することによって整合を得る方法を考察している.このtanδe補正とは, tanδeが適正値より小さい材料に対しては抵抗皮膜を, 適正値より大きい材料においては無損失誘電体と組み合わせて整合を得るものである.

A polarization-reflection type of light modulator is proposed to utilize the deviation of reflectance of polarized light incident on an electro-optical medium at an angle greater than the Brewster angle. Feasibility of this method is theoretically investigated for the cases of real as well as complex refractive index. From numerical calculations it is shown that the intensity of light changes linearly with applied voltage under a certain condition, and that this method is applicable to such a ferroelectric materials as BaTiO,, SBN and other crystals. The modulation of He-Ne laser or Arf laser is demonstrated experimentally at radio frequencies using a BaTiO, crystal. The merits of this type of light modulator are discussed and compared with crossed-polarizer tyoe of light modulator.